CN207423488U - A kind of big load piece box type balance for hold-down test - Google Patents

Abstract

A large-load sheet box balance for test bench tests, including a fixed frame (1), a floating frame (2), a model end (3), a longitudinal load elastic column beam group (4), and an axial force elastic sheet beam group (5), measuring unit; one end of the longitudinal load elastic column beam group (4) is connected to the fixed frame (1), and the other end is connected to the floating frame (2); one end of the axial force elastic sheet beam group (5) is connected to The floating frame (2), the other end is connected to the model end (3); the measurement unit includes 3 Wheatstone bridges, and each Wheatstone bridge is composed of 8 strain gauges (42) connected in sequence, of which 2 Wheatstone bridges The bridge is pasted on the upper and lower surfaces of the longitudinal load elastic column beam group (4); the remaining 1 Wheatstone bridge is pasted on the axial force elastic sheet beam group (5).

Description

A large-load piece box balance for test bench test

technical field

The utility model relates to a large-load piece box type balance used for test bench tests, which belongs to the field of measurement.

Background technique

The ramjet engine and combined cycle power system have good application prospects in high-speed aircraft, cruise aircraft and near-space vehicles, and the high-precision prediction of the aerodynamic characteristics of the aircraft in different flight states before and after the ignition of the power system is an important aspect of its development and application. link. At present, in the test bench wind tunnel test, the aerodynamic performance of the power system before and after ignition is mainly measured by several parallel balances placed at the bottom of the test bench support to measure the force separately and jointly solve it. This kind of external balance measurement method has the following problems: (1) The weight of the model, especially the weight of the support frame, is relatively large, and its center of mass deviates from the design center of the balance. The design of the balance is rigid, the output of the balance is small after being loaded during the test, and the longitudinal measurement accuracy is low; (2) In the wind tunnel test of the test bench, the load change of each component of the aircraft before and after the ignition of the power system is seriously mismatched, and the change of the pitching moment is much smaller than that of the axis. (3) The vertical and axial interference of parallel external balances is large, so the axial measurement accuracy is low.

Utility model content

The purpose of the utility model is to overcome the above-mentioned deficiencies of the prior art, by solving the problem of accurate measurement of the aerodynamic load during the test run of the ramjet engine, to design a large-load sheet-cassette type with low cost and higher measurement accuracy than the existing measurement method scales. In order to reduce the self-weight interference of the model and the bracket, the balance is placed in the inner cavity of the model, and the design center is as close as possible to the center of mass of the model to reduce the interference of the model's own weight on the longitudinal measurement; in addition, due to the height limitation of the inner cavity of the model, The balance with cassette layout has high measurement sensitivity, good rigidity and little interference.

The above-mentioned purpose of the utility model is achieved through the following technical solutions:

A large-load sheet box balance for test bench tests, including a fixed frame, a floating frame, a model end, a longitudinal load elastic column beam group, an axial force elastic sheet beam group, and a measuring unit;

One end of the longitudinal load elastic column beam group is connected to the fixed frame, and the other end is connected to the floating frame; one end of the axial force elastic sheet beam group is connected to the floating frame, and the other end is connected to the model end;

The measurement unit includes M Wheatstone bridges, and each Wheatstone bridge is composed of N strain gauges connected sequentially, among which P Wheatstone bridges are pasted on the upper and lower surfaces of the longitudinally loaded elastic column-beam group; the remaining M-P Wheatstone bridges are The energized bridge is pasted on the axial force elastic sheet beam group; where M, P, and N are all positive integers, and M is greater than P, and P is an even number.

In the above-mentioned large-load chip box balance used for test bench tests, the fixed frame is a rectangular box, and the box is provided with an opening for connecting the longitudinal load elastic column beam group; the floating frame is a rectangular frame, and the model The end is a cuboid; the longitudinal load elastic column beam group includes four identical elastic column beams, and the elastic column beam is a cuboid; one end of each elastic column beam is connected with a fixed frame, and the other end is connected with a floating frame.

The above-mentioned large-load sheet box-type balance used for the test bench test, the 2 Wheatstone bridges pasted on the longitudinal load elastic column beam group, each Wheatstone bridge is composed of 8 strain gauges; the 8 The two strain gauges are divided into four groups and facing each other in pairs, pasted on the upper and lower surfaces of the connecting root of the elastic column beam and the fixed frame, and close to the fixed frame; normal force and pitching moment.

In the above-mentioned large-load sheet box balance used for test bench tests, the axial force elastic sheet beam group includes two elastic sheet beams and two sets of support sheet beams, and each support sheet beam includes a first support sheet beam and a second support sheet beam. Support beams.

The above-mentioned large-load sheet box balance used for test bench tests, the two elastic sheet beams are located in the middle of the length direction of the model end, and one end of each elastic sheet beam is connected to the floating frame, and the other end is connected to the model end; The first support sheet beam includes forty spring sheets whose shapes are all cuboids, and every ten spring sheets are arranged in parallel and equally spaced as a group, and each group of spring sheets is located on both sides of the model end close to the position of the longitudinal load elastic column beam group; The second supporting sheet beam includes eight supporting sheets all in the shape of a cuboid, and every two supporting sheets are arranged in parallel and equally spaced as a group, and each group of supporting sheets is located on both sides of the model end close to the elastic sheet beam.

The above-mentioned large-load sheet box balance used for the test bench test, the 1 Wheatstone bridge pasted on the axial force elastic sheet beam group, the Wheatstone bridge is composed of 8 strain gauges; the above 8 strain gauges The sheets are divided into four groups and then face each other in pairs, and one group is pasted on both sides of each elastic sheet beam; the Wheatstone bridge is used to measure the axial force of the large-load sheet box balance after being loaded.

The above-mentioned large-load chip box balance used for test bench tests, the large-load chip box balance has a first axis of symmetry and a second axis of symmetry, the first axis of symmetry is parallel to the length direction of the fixed frame, and the second The axial symmetry plane is parallel to the width direction of the fixed frame; the longitudinal load elastic column beam group is arranged symmetrically with respect to the above two opposing surfaces; the axial force elastic sheet beam group is symmetrically arranged about the above two opposing surfaces.

In the above-mentioned large-load chip box balance used for the test bench test, the root of the spring leaf connected to the floating frame, and the root of the spring leaf connected to the model end are all rounded, and the radius of the rounded corner is 0.5 mm to 1 mm.

In the above-mentioned large-load chip box balance used for the test bench test, bolt holes are opened on the fixed frame.

In the above-mentioned large-load cassette balance used for test bench tests, there are bolt holes on the model end for positioning and connection between the large-load cassette balance and the model to be tested; the surface of the model end is provided with a concave Groove, the groove is located in the middle of the model end, and the depth of the groove is 1mm to 2mm.

The above-mentioned large-load sheet box balance used for test bench tests, the fixed frame, the floating frame, the model end, the longitudinal load elastic column beam group, and the axial force elastic sheet beam group are integrally processed and formed.

For the above-mentioned large-load sheet box balance used for test bench tests, the measurement unit includes 3 Wheatstone bridges, and each Wheatstone bridge is composed of 8 strain gauges connected in sequence, of which 2 Wheatstone bridges are pasted On the upper and lower surfaces of the longitudinal load elastic column beam group; the remaining 1 Wheatstone bridge is pasted on the axial force elastic sheet beam group.

The beneficial effects of the utility model compared with the prior art are:

(1) The utility model chip box structure balance makes full use of the inner cavity space of the model, and places it in the model cavity, and makes its design center as close as possible to the center of mass of the model, which solves the balance sensitivity caused by the interference of the model and the self-weight of the bracket Low problem, improve the longitudinal measurement accuracy;

(2) The balance of the utility model with a cassette structure adopts a double-floating frame design. Under the action of a longitudinal load, the elastic beam of the axial force hardly deforms, and the balance has a strong ability to resist longitudinal interference in the axial direction. The problem of large component interference and large measurement error; at the same time, the use of multi-spring supports improves the balance rigidity;

(3) The utility model adopts a symmetrical layout structure, which reduces the mutual interference between the components, solves the complex problem of box-type balance processing and patching technology, and facilitates the mechanical processing of the balance and the pasting of strain gauges.

Description of drawings

Fig. 1 is the schematic diagram of the three-dimensional structure of the utility model large-load sheet cassette balance;

Fig. 2 is the front view of the utility model large-load piece box type balance;

Fig. 3 is the cross-sectional view of the A-A plane of the utility model large load piece box balance;

Fig. 4 is the cross-sectional view of the B-B plane of the large-load sheet box balance of the present invention and the schematic diagram of sticking the strain gauge;

Fig. 5 is a schematic diagram of sticking the longitudinal unit strain gauges of the utility model;

Fig. 6 is a Wheatstone circuit diagram composed of strain gauges in the utility model's large load cell box balance.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail:

Fig. 1 is a three-dimensional structural schematic diagram of a large-load sheet cassette balance of the present invention, and Fig. 2 is a front view of a large-load sheet cassette balance of the present invention, including: a fixed frame 1, a floating frame 2, a model end 3, and a longitudinal load Elastic column beam group 4, axial force elastic sheet beam group 5, measuring unit; the fixed frame 1 is a rectangular box with an opening for connecting the longitudinal load elastic column beam group 4, and the box body is used It accommodates the floating frame 2, the model end 3, the longitudinal load elastic column beam group 4, the axial force elastic sheet beam group 5, and the measurement unit, as shown in Figure 4; the floating frame 2 is a rectangular frame, and the model end 3 It is a cuboid; the longitudinal load elastic column beam group 4 is located between the fixed frame 1 and the floating frame 2, one end is connected to the fixed frame 1, and the other end is connected to the floating frame 2; the axial force elastic sheet beam group 5 is located in the floating frame 2 Between the model end 3 and the floating frame 2 at one end, and the model end 3 at the other end.

The fixed frame 1, the floating frame 2, the model end 3, the longitudinal load elastic column beam group 4, and the axial force elastic sheet beam group 5 are integrally processed and formed, that is, processed by wire cutting technology, which solves the complicated processing technology of the box balance. question. There are bolt holes on the fixed frame 1, which are fastened to the supporting device through bolts. The bolt connections distributed in arrays enhance the rigidity of the fixed frame and reduce the deformation interference of the fixed frame.

Bolt holes are provided on the model end 3, which are used for positioning and connection between the large-load film cassette balance and the measured model; the surface of the model end 3 is provided with a groove, and the groove is located in the middle of the model end 3, The groove depth is 1mm-2mm. The bolt holes and grooves are used for the fast connection and positioning between the balance and the model, which improves the positioning accuracy of the model and the balance installation.

The longitudinal load elastic column beam group 4 includes four identical elastic column beams 41, and the elastic column beams 41 are cuboids; one end of each elastic column beam 41 is connected with the fixed frame 1, and the other end is connected with the floating frame 2, as shown in the figure 3.

The axial force elastic sheet beam group 5 includes two elastic sheet beams 51 and two sets of supporting sheet beams 52 , and each supporting sheet beam 52 includes a first supporting sheet beam 521 and a second supporting sheet beam 522 . The two elastic sheet beams 51 are located in the middle of the length direction of the model end 3, and one end of each elastic sheet beam 51 is connected to the floating frame 2, and the other end is connected to the model end 3; the first support sheet beam 521 includes forty Each spring sheet is rectangular parallelepiped, and every ten spring sheets are arranged in parallel and equally spaced as a group, and each group of spring sheets is located on both sides of the model end 3 and is close to the position of the longitudinal load elastic column beam group 4; the second support The sheet beam 522 includes eight support sheets all of which are cuboid in shape, and every two support sheets are arranged in parallel and equally spaced as a group, and each group of support sheets is located on both sides of the model end 3 near the elastic sheet beam 51 . The root of the spring piece connected to the floating frame 2 and the root of the spring piece connected to the model end 3 are all rounded, and the radius of the rounded corner is 0.5mm-1mm, so as to reduce the stress concentration after the balance is loaded. The double floating frame design is adopted, under the action of longitudinal load, the axial force elastic sheet beam hardly deforms, and the balance has a strong ability to resist longitudinal interference in the axial direction. At the same time, the multi-spring support method improves the balance rigidity.

The large-load sheet cassette balance has a first axisymmetric plane and a second axisymmetric plane, the first axisymmetric plane is parallel to the length direction of the fixed frame 1, and the second axisymmetric plane is parallel to the width direction of the fixed frame 1; The load elastic column beam group 4 is arranged symmetrically with respect to the above two opposing surfaces; the axial force elastic sheet beam group 5 is arranged symmetrically with respect to the above two opposing surfaces. Strain gauges 42 are provided on the surfaces of the four elastic column beams 41, which are used to measure the normal force and pitching moment after the balance is loaded. The four elastic column beams 41 are symmetrical about the first axisymmetric plane and the second axisymmetric plane layout, the output signal is large and the interference is small. The same symmetrical distribution of the axial force elastic plate beam group 5 also reduces the mutual interference between the components, and facilitates the mechanical processing of the balance and the sticking of the strain gauges.

In this embodiment, the measurement unit includes 3 Wheatstone bridges, and each Wheatstone bridge is composed of 8 strain gauges 42 connected in sequence, and 2 Wheatstone bridges are pasted on the upper and lower surfaces of the longitudinal load elastic column beam group 4 ; The remaining 1 Wheatstone bridge is pasted on the axial force elastic sheet beam group 5 .

The 1 Wheatstone bridge pasted on the axial force elastic sheet beam group 5 includes 8 strain gauges 42; the above-mentioned 8 strain gauges 42 are divided into four groups and then two by two are opposite, and each elastic sheet beam 51 One group is pasted on each side of each elastic sheet beam 51, and the pasting position is the middle position of each elastic sheet beam 51, as shown in Figure 4; the axial force measurement unit is used to measure the axial force of the large load sheet cassette balance after being loaded .

The 2 Wheatstone bridges pasted on the longitudinal load elastic column-beam group 4, each Wheatstone bridge includes 8 strain gauges 42; the above-mentioned 8 strain gauges 42 are divided into four groups and are opposite to each other. On the upper and lower surfaces of the root of the connection between the elastic column beam 41 and the fixed frame 1, close to the fixed frame 1; two Wheatstone bridges are used to measure the normal force and pitching moment of the large-load film box balance after being loaded, as shown in Figure 5 shown.

The working principle of the heavy-duty cassette balance is as follows:

Figure 6 shows the circuit diagram of the Wheatstone bridge. Every 8 strain gauges form a Wheatstone bridge. The bridge voltage is given and the signal output is measured. The balance of the utility model forms three Wheatstone bridges by arranging strain gauges on the measuring beam, and measures normal force, pitching moment and axial force respectively. When the balance is subjected to a longitudinal load, the elastic column beam 41 undergoes elastic deformation, and 16 strain gauges pasted on the four elastic column beams 41 form two Wheatstone bridges to linearly convert the deformation into electrical signals, and measure the normal direction respectively. force and pitching moment. When the balance is subjected to an axial load, the elastic sheet beam 51 undergoes elastic deformation, and the 8 strain gauges pasted on the two elastic sheet beams 51 form a Wheatstone bridge to linearly convert the deformation into an electrical signal and measure the axial force .

When the balance is subjected to a longitudinal load, the elastic column beam 41 can be regarded as a statically indeterminate beam, that is, a "double bending" deformation occurs under the action of a normal force or a pitching moment (the normal direction is the direction perpendicular to the paper in Figure 5). According to the principle of consistent deformation, when bearing the normal force, the four elastic column beams 41 bear the same load and produce symmetrical deformation about the second axis of symmetry, and the strain gauges 421 and 422 are arranged on the upper surfaces of the four elastic column beams 41 , the strain gauges 423 and 424 are arranged on the corresponding positions of the lower surfaces of the four elastic column beams 41 (in this group of electric bridges, the strain gauges 421 are strain gauges a and strain gauges b, and the strain gauges 422 are strain gauges e and strain gauges f, the strain gauge 423 is the strain gauge c and the strain gauge d, and the strain gauge 424 is the strain gauge g and the strain gauge h). When bearing the pitching moment, the four elastic column beams 41 bear the same load and deform in opposite directions with respect to the second axisymmetric plane. The strain gauges 425 and 426 are arranged on the upper surfaces of the four elastic column beams 41, and the strain gauges 427 and The gauges 428 are arranged at corresponding positions on the lower surfaces of the four elastic beams 41 (in this group of electric bridges, the strain gauges 425 are strain gauges a and strain gauge b, the strain gauges 426 are strain gauges c and strain gauge d, and the strain gauges 427 are strain gauges The strain gauge e and the strain gauge f, the strain gauge 428 are the strain gauge g and the strain gauge h).

When the balance is subjected to an axial load, the elastic sheet beam 51 can be regarded as a statically indeterminate beam, that is, it undergoes "double bending" deformation under the action of an axial force (the axial direction is the direction perpendicular to the paper in FIG. 4 ). According to the principle of consistent deformation, most of the axial loads are borne by the two elastic sheet beams 51 . When bearing the axial force, the two elastic sheet beams 51 bear the same load and produce symmetrical deformation with respect to the first axisymmetric plane. The strain gauges 5121 and 5122 are arranged at the roots of the two elastic sheet beams 51, and the strain gauges 5123 and 5122 The strain gauges 5124 are arranged at the corresponding positions of the roots on the other side of the two elastic beams 51 (in FIG. strain gauge e and strain gauge f, and strain gauge 5124 is strain gauge g and strain gauge h). When the balance is subjected to a longitudinal load, since the supporting beam 52 is much stiffer than the elastic beam 51 in the longitudinal direction, the supporting beam 52 bears most of the longitudinal load, the elastic beam 51 hardly deforms, and the Wheatstone bridge does not The electrical signal is output, so the longitudinal load has less interference with the axial direction.

To sum up, the utility model can realize the accurate measurement of the aerodynamic load during the test run of the ramjet at low cost.

The above is only the best specific implementation of the utility model, but the scope of protection of the utility model is not limited thereto, and any person familiar with the technical field can easily think of the technical scope disclosed in the utility model Changes or replacements should fall within the protection scope of the present utility model.

The content that is not described in detail in the description of the utility model belongs to the known technology of those skilled in the art.

Claims (12)

1. a kind of big load piece box type balance for hold-down test, it is characterised in that：Including fixed frame (1), floating frame (2), model end (3), longitudinal loading elastic beam group (4), axial force elastic piece beam group (5), measuring unit；

Longitudinal loading elastic beam group (4) one end connection fixed frame (1), other end connection floating frame (2)；The axial force Elastic piece beam group (5) one end connection floating frame (2), other end link model end (3)；

Measuring unit includes M Wheatstone bridge, and each Wheatstone bridge is sequentially connected by N number of foil gauge (42) and formed, Middle P Wheatstone bridge is pasted onto the upper and lower surface of longitudinal loading elastic beam group (4)；Remaining M-P Wheatstone bridge is pasted In axial force elastic piece beam group (5)；Wherein M, P, N are positive integer, and M is more than P, and P is even number.

2. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：It is described Fixed frame (1) is rectangle box body, and box body is equipped with opening, for connecting longitudinal loading elastic beam group (4)；The floating frame (2) it is rectangle framework, model end (3) are cuboid；The longitudinal loading elastic beam group (4) includes four identical elasticity Column beam (41), elastic beam (41) are cuboid；One end of each elastic beam (41) is connected with fixed frame (1), the other end Connect floating frame (2).

3. a kind of big load piece box type balance for hold-down test according to claim 2, it is characterised in that：It is described 2 Wheatstone bridges being pasted onto in longitudinal loading elastic beam group (4), each Wheatstone bridge is by 8 foil gauges (42) Composition；8 foil gauges (42) are divided into after four groups two-by-two relatively, are pasted onto elastic beam (41) and are connected root with fixed frame (1) The upper and lower surface in portion, closely fixed frame (1)；After above-mentioned 2 Wheatstone bridges are for measuring big load piece box type balance stand under load Normal force and pitching moment.

4. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：It is described Axial force elastic piece beam group (5) includes two elastic piece beams (51) and two groups of support chip beams (52), each support chip beam (52) bag Include the first support chip beam (521) and the second support chip beam (522).

5. a kind of big load piece box type balance for hold-down test according to claim 4, it is characterised in that：It is described Two elastic piece beams (51) are located at the centre of model end (3) length direction, and one end of each elastic piece beam (51) is all connected with floating Frame (2), the other end are all connected with model end (3)；The first support chip beam (521) includes the bullet that 40 shapes are cuboid Reed, every ten spring leafs are parallel to be equidistantly arranged as one group, and every group of spring leaf is respectively positioned on the both sides at model end (3) close to longitudinal direction The position of load elastic beam group (4)；The second support chip beam (522) includes the support chip that eight shapes are cuboid, Each two support chip is parallel to be equidistantly arranged as one group, and every group of support chip is respectively positioned on the both sides at model end (3) close to elastic piece beam (51) position.

6. a kind of big load piece box type balance for hold-down test according to claim 4, it is characterised in that：It is described 1 Wheatstone bridge being pasted onto in axial force elastic piece beam group (5), the Wheatstone bridge are made of 8 foil gauges (42)；On It states 8 foil gauges (42) to be divided into after four groups two-by-two relatively, respectively pastes one group in the both sides of each elastic piece beam (51)；The favour stone Electric bridge is used to measure the measurement of the axial force after big load piece box type balance stand under load.

7. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：It is described Big load piece box type balance has the first axle plane of symmetry and the second axial symmetry face, the length of the first axle plane of symmetry and fixed frame (1) Direction is parallel, and the second axial symmetry face is parallel with the width of fixed frame (1)；Longitudinal loading elastic beam group (4) is on above-mentioned Two faces poised for battle are arranged symmetrically；Axial force elastic piece beam group (5) is poised for battle face on above-mentioned two and is arranged symmetrically.

8. a kind of big load piece box type balance for hold-down test according to claim 5, it is characterised in that：It is described Root that spring leaf is connected with floating frame (2) and, the equal rounded corner in root that spring leaf is connected with model end (3), rounded corner half Footpath is 0.5mm~1mm.

9. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：It is described Fixed frame is provided with bolt hole on (1).

10. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：Institute It states and is provided with bolt hole on model end (3), for the positioning and connection between big load piece box type balance and tested model；The model The surface of (3) is held to be equipped with groove, groove is located at the middle part at model end (3), and depth of groove is 1mm~2mm.

11. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：Institute State fixed frame (1), floating frame (2), model end (3), longitudinal loading elastic beam group (4), axial force elastic piece beam group (5) be one Body machine-shaping.

12. a kind of big load piece box type balance for hold-down test according to claim 1, it is characterised in that：Institute Stating measuring unit includes 3 Wheatstone bridges, and each Wheatstone bridge is sequentially connected by 8 foil gauges (42) and formed, wherein 2 A Wheatstone bridge is pasted onto the upper and lower surface of longitudinal loading elastic beam group (4)；Remaining 1 Wheatstone bridge is pasted onto axial direction In power elastic piece beam group (5).