CN109580163B - Torsion balance type two-degree-of-freedom force measuring balance and calibration and force measuring method thereof - Google Patents
Torsion balance type two-degree-of-freedom force measuring balance and calibration and force measuring method thereof Download PDFInfo
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- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
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- G—PHYSICS
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Abstract
The invention relates to a torsion balance type two-degree-of-freedom force measuring balance and a calibration and force measuring method thereof, belonging to the field of test and test. The force measuring balance comprises a balance frame mechanism, an optical measuring mechanism and a calibration mechanism; the balance platform frame mechanism is used for decomposing vector force borne by the test model into horizontal and vertical direction components and generating torsional deformation in the horizontal and vertical directions; the optical measuring mechanism is used for measuring the horizontal and vertical torsional deformation of the platform frame mechanism; the calibration mechanism is used for calibrating the measurement process of the optical measurement mechanism. The balance platform frame mechanism realizes measurement of stress components of the test model in two directions, and the balance can realize on-line real-time calibration of a force measuring process by utilizing an electromagnetic calibration device which is formed by a permanent magnet array and a straight lead array on two force measuring freedom degrees respectively.
Description
Technical Field
The invention relates to a force measuring balance and a calibration and force measuring method thereof, belonging to the technical field of vehicle force measurement tests.
Background
The wind tunnel or water tunnel model test can provide key test parameters and design basis for the development of novel aircrafts, automobiles, high-speed rails, ships and warships and the like; particularly for the research of complex flow problems, the experimental measurement of model aerodynamic force and underwater resistance is irreplaceable by computer simulation and is an important tool means for determining the success or failure of related research.
At present, a mechanical balance, a strain balance and the like are commonly adopted in wind tunnel or water tunnel tests to carry out force measurement tests. The traditional mechanical balance has large volume, is easily influenced by environmental factors such as humidity and the like, and has relatively high manufacturing cost. For a measuring environment or a test working condition with strong electromagnetic radiation, the strain balance may have electromagnetic interference to cause difficulty in accurate measurement. If the electromagnetic radiation is not adequately protected and leaks during the test, it may cause the measurement signal to be subject to electromagnetic interference and even cause the strain balance measurement to fail. In addition, the research of micro aircrafts and micro underwater vehicles puts higher requirements on the high-precision measurement of micro aerodynamic force and hydrodynamic force, and balances need to have the force measuring capability of a few milli-newtons, hundreds of micro-newtons and even better. The measurement accuracy of the existing mechanical and strain balance can not completely meet the requirement of high-accuracy force measurement.
Disclosure of Invention
The invention aims to solve the technical problem of providing a torsion balance type two-degree-of-freedom force measuring balance aiming at the defects in the background technology, and the torsion balance type two-degree-of-freedom force measuring balance can obtain higher-precision force measuring capability of wind tunnel and water tunnel tests.
In order to solve the technical problems, the invention adopts the following technical scheme:
a torsion balance type two-degree-of-freedom force measuring balance comprises a balance frame mechanism, an optical measuring mechanism and a calibration mechanism; the balance platform frame mechanism is used for decomposing vector force borne by the test model into horizontal and vertical direction components and generating torsional deformation in the horizontal and vertical directions; the optical measuring mechanism is used for measuring the horizontal and vertical torsional deformation of the platform frame mechanism; the calibration mechanism is used for calibrating the measurement process of the optical measurement mechanism.
The invention relates to a torsion balance type two-degree-of-freedom force measuring balance.A balance platform frame mechanism comprises a torsion arm, a first torsion bar, a second torsion bar, a third torsion bar, a fourth torsion bar and a support frame;
the support frame comprises a model support frame, a balance fixing support frame, a balance moving support frame and a balance center support frame;
the test model is connected with the torque arm through the model supporting frame;
the torsion arm is provided with a balance weight to balance the weight of the test model;
the torsion arm is connected to a second torsion bar and a fourth torsion bar which are vertically arranged through a balance center supporting frame; the upper end of the second torsion bar and the lower end of the fourth torsion bar are connected to a balance moving support frame; the balance moving support frame is connected to the first torsion bar and the third torsion bar; the first torsion bar and the third torsion bar are connected to a balance fixing support frame;
the balance fixing support frame is arranged on the ground base and is kept stable;
the first torsion bar is collinear with the central axis of the third torsion bar, the second torsion bar is collinear with the central axis of the fourth torsion bar, and the two axes are mutually perpendicular and intersect at one point.
The invention relates to a torsion balance type two-degree-of-freedom force measuring balance.A first laser, a first facula displacement sensor and a plane reflector form a group of optical measuring devices; the plane reflector, the second laser and the second light spot displacement sensor form another group of optical measuring devices;
the plane mirror is arranged in the balance center support frame and is positioned on a plane formed by the central axes of the first torsion bar, the third torsion bar, the second torsion bar and the fourth torsion bar;
when the test model is subjected to acting force in the horizontal direction, the torsion arm rotates around the second torsion bar and the fourth torsion bar, and the plane mirror synchronously rotates in a plane vertical to the central axes of the second torsion bar and the fourth torsion bar;
when the test model is subjected to acting force in the vertical direction, the torsion arm rotates around the first torsion bar and the third torsion bar, and the plane mirror synchronously rotates in a plane vertical to the central axes of the first torsion bar and the third torsion bar;
when the test model is subjected to acting forces in the horizontal and vertical directions, the torsion arm and the plane mirror rotate around the central axes of the second torsion bar and the fourth torsion bar and the central axes of the first torsion bar and the third torsion bar, and the reflecting point on the plane mirror is a fixed point, so that the balance frame mechanism can be effectively decoupled when the horizontal and vertical directions of the test model are measured;
the first laser and the first light spot displacement sensor are arranged in a horizontal plane where the first torsion bar is intersected with the central axis of the third torsion bar; the second laser and the second light spot displacement sensor are arranged in a plane which is perpendicular to the central axes of the first torsion bar and the third torsion bar and passes through the central axes of the second torsion bar and the fourth torsion bar;
laser beams generated by the first laser and the second laser are respectively reflected to the first light spot displacement sensor and the second light spot displacement sensor by the plane reflector, so that light spots are subjected to displacement vibration on the photosensitive surface;
the first light spot displacement sensor and the second light spot displacement sensor output electric signals respectively representing stress components of the test model in the horizontal direction and the vertical direction.
The invention relates to a torsion balance type two-degree-of-freedom force measuring balance, wherein a calibration mechanism comprises an electromagnetic calibration mechanism and a weight calibration mechanism;
the electromagnetic calibration devices are arranged in two groups and are respectively arranged on the torque arms, and the ampere force applied to the magnetic field formed by the permanent magnet by the electrified straight conducting wires is used as calibration force;
the first group of electromagnetic calibration devices are composed of a permanent magnet array I and a straight wire array I and generate a calibration force in the horizontal direction; the second group of electromagnetic calibration devices generate a calibration force in the vertical direction by a permanent magnet array II and a straight wire array II;
the weight calibration mechanisms are divided into two groups, and the first group of weight calibration mechanisms are arranged below the first group of electromagnetic calibration devices; the second group of weight calibration mechanisms are arranged below the second group of electromagnetic calibration devices; the two groups of weight calibration mechanisms are used for calibrating the relationship between the current and the calibration force of the electromagnetic calibration device;
the first group of weight calibration mechanisms are formed by a pull rope, a connecting torque arm and a weight tray I, and the direction of the calibration force is changed from vertical direction to horizontal direction by using a pulley; and the second group of weight calibration mechanisms are formed by connecting a second pull rope with a second torque arm and a second weight tray.
The invention relates to a torsion balance type two-degree-of-freedom force measuring balance, and a calibration method of an electromagnetic calibration device thereof comprises the following steps:
1) the electromagnetic calibration device is not electrified, weights with various masses are placed in the weight tray I and the weight tray II, the gravity of the weights is used as calibration force, and electric signals output by the optical measurement mechanism on each force measurement freedom degree are collected and recorded;
2) obtaining a relation curve of weight scaling force and output electric signals on each force measuring freedom degree through the step 1);
3) weights in the first weight tray and the second weight tray are taken away, the electromagnetic calibration device is electrified, and ampere force is used as calibration force;
4) setting the current of the electromagnetic calibration device to be different values, generating corresponding calibration force by the electromagnetic calibration device, and simultaneously collecting and recording electric signals output by the optical measurement mechanism on each force measurement freedom degree;
5) obtaining a relation curve of the electrified current and the output electric signal of the electromagnetic calibration device on each force measuring freedom degree through the step 4);
6) comparing the relation curve and the data in the step 2) and the step 5) to obtain a relation curve of the electrifying current and the calibration force of the electromagnetic calibration device;
7) and repeating the steps 1) to 6) for a plurality of times, fitting to obtain an average relational expression of the electrified current and the calibration force of the electromagnetic calibration device, and ending the calibration process of the electromagnetic calibration device.
The invention relates to a force measuring method of a torsion balance type two-degree-of-freedom force measuring balance, which comprises the following steps:
1) mounting a test model on the sky platform frame mechanism through the model support frame, and mounting the sky platform frame mechanism on a test section of a wind tunnel or a water tunnel;
2) utilizing the balance weight to adjust the balance platform frame mechanism to be in a balance position;
3) adjusting the positions of the first light spot displacement sensor and the second light spot displacement sensor to enable the output electric signal to return to zero and enable the length of a laser light path to meet the requirement of a force measuring range;
4) starting all the electromagnetic calibration devices, adjusting the current of the electromagnetic calibration devices to different values, collecting and recording the electric signals output by the optical measurement mechanism on each force measurement degree of freedom, and obtaining a relation curve between the calibration force of the electromagnetic calibration devices on each force measurement degree of freedom and the output electric signals;
5) closing all the electromagnetic calibration devices, and entering a test stage;
6) the test model starts to work, and electric signals output by the optical measurement mechanism on each force measurement freedom degree are collected and recorded;
7) and obtaining the vector force component in the corresponding direction through the relation curve of the electromagnetic calibration force on each force measurement freedom degree and the output electric signal.
The invention adopts the technical means to have the following technical effects:
the balance platform frame mechanism utilizes a torsion arm, a torsion bar, a model support frame, a balance fixing support frame, a balance moving support frame and a balance central support frame structure to realize the measurement of the stress components of the test model in two directions, and the force measurement processes in the two directions are mutually decoupled;
the balance utilizes the plane reflector, the laser and the facula displacement sensor to form an optical measuring mechanism on two force-measuring degrees of freedom, so that the torsional deformation on the two force-measuring degrees of freedom can be measured simultaneously, and the laser and the facula displacement sensor can be arranged at positions far away from a test site, so that electromagnetic shielding and constant temperature and humidity maintenance are facilitated, and the problem of interference of a complex working process of a test model on the balance measurement is solved;
the balance utilizes an electromagnetic calibration device which is formed by a permanent magnet array and a straight lead array on two force measurement freedom degrees respectively, so that the on-line real-time calibration of the force measurement process can be realized;
the weight calibration device is used for calibrating the electromagnetic calibration device, the relation between the electrifying current of the electromagnetic calibration device and the electromagnetic calibration force is calibrated, the electromagnetic calibration device does not need to be detached from the balance in the calibration process, and the weight calibration device does not influence the force measurement process of the balance.
Drawings
Fig. 1 is a schematic view of the structure of the present invention.
Fig. 2 is a schematic structural diagram of the electromagnetic calibration device of the present invention.
Detailed Description
In order to make the purpose and technical solution of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
The invention decomposes the vector force borne by the test model, respectively converts the acting force component applied on the test model into tiny torsional deformation by using the torsion balance principle in two degrees of freedom, simultaneously converts the deformation into an electric signal by using an optical lever amplification method, and finally realizes high-precision force measurement by measuring the amplified electric signal.
As shown in fig. 1: the balance is composed of a balance platform frame mechanism, an optical measuring mechanism and a calibration mechanism.
The sky terrace frame mechanism is used for decomposing the vector force received by the test model 1 into a horizontal direction and a vertical direction, as shown in the x direction and the y direction in fig. 1. The balance platform frame mechanism comprises a torsion arm 3, a first torsion bar 7, a second torsion bar 10, a third torsion bar 12, a fourth torsion bar 23 and a support frame. The support frame comprises a model support frame 2, a balance fixing support frame 13, a balance moving support frame 9 and a balance center support frame 20.
The test model 1 is connected with a torque arm 3 through a model support frame 2. The torque arm 3 is connected to the balance center support 20, and a counterweight 16 is provided on the torque arm 3 for balancing the weight of the test model 1. The torsion arm 3 is connected to a second torsion bar 10 and a fourth torsion bar 23 which are vertically arranged through a balance center support frame 20. The upper end of the second torsion bar 10 and the lower end of the fourth torsion bar 23 are connected to the balance moving support 9. Balance moving support 9 is connected to torsion bar one 7 and torsion bar three 12. The first torsion bar 7 and the third torsion bar 12 are connected to a balance fixing support frame 13. The balance fixing support frame 13 is installed on a ground base and keeps stable and fixed.
The central axes of the first torsion bar 7 and the third torsion bar 12 are collinear, the central axes of the second torsion bar 10 and the fourth torsion bar 23 are collinear, and the two axes are perpendicular to each other and intersect at a point. A plane mirror 8 is arranged on the plane formed by the two axes. The intersection point of the two axes is located at the center of the plane mirror 8 and is a laser reflection point. The plane mirror 8 is mounted in the balance center support 20.
The optical measurement mechanism is used for measuring mechanical deformation of the platform frame mechanism in all directions and comprises two groups of optical measurement devices, wherein a first laser 14, a first light spot displacement sensor 21 and the plane reflector 8 form a group of optical measurement devices; the plane reflector 8, the second laser 11 and the second spot displacement sensor 22 form another group of optical measuring devices.
As shown in fig. 1, the laser first 14 and the spot displacement sensor first 21 are arranged in a horizontal plane intersecting the central axes of the torsion bar first 7 and the torsion bar third 12 so that the laser beam generated by the laser first 14 falls on the reflection point of the plane mirror 8 and is reflected onto the photosensitive surface of the spot displacement sensor first 21. And the first light spot displacement sensor 21 outputs an electric signal corresponding to the stress of the test model 1 in the x direction. The second laser 11 and the second spot displacement sensor 22 are arranged in a plane which is perpendicular to the central axes of the first torsion bar 7 and the third torsion bar 12 and passes through the central axes of the second torsion bar 10 and the fourth torsion bar 23. And the second light spot displacement sensor 22 outputs an electric signal corresponding to the stress of the test model 1 in the y direction.
As shown in fig. 1, when the test model 1 is subjected to an acting force in the x direction, the test model 1 pushes the model support frame 2 to drive the torsion arm 3 to rotate around the second torsion bar 10 and the fourth torsion bar 23 by a certain angle until the restoring moment generated by the second torsion bar 10 and the fourth torsion bar 23 is the same as the moment of the acting force in the x direction on the second torsion bar 10 and the fourth torsion bar 23. As the torsion arm 3 rotates around the second torsion bar 10 and the fourth torsion bar 23, the plane mirror 8 synchronously rotates in a plane perpendicular to the central axes of the second torsion bar 10 and the fourth torsion bar 23, so that the laser beam generated by the first laser 14 is reflected to the first spot displacement sensor 21. And an electric signal synchronously output by the first light spot displacement sensor 21 represents the stress of the test model 1 in the x direction.
Similarly, when the test model 1 is subjected to the acting force in the y direction, the test model 1 drives the model support frame 2 to move so as to drive the torsion arm 3 to rotate around the first torsion bar 7 and the third torsion bar 12, so that the plane mirror 8 synchronously rotates in the plane vertical to the first torsion bar 7 and the third torsion bar 12.
When the test model 1 is subjected to forces in the x and y directions simultaneously, the torsion arm 3 will rotate around the central axes of the second torsion bar 10 and the fourth torsion bar 23 and the central axes of the first torsion bar 7 and the third torsion bar 12 simultaneously. Considering that the intersection point of the two central axes is not moved when the second torsion bar 10, the fourth torsion bar 23, the first torsion bar 7 and the third torsion bar 12 rotate, the position of the reflection point is not moved when the plane mirror 8 simultaneously rotates around the second torsion bar 10, the fourth torsion bar 23, the first torsion bar 7 and the third torsion bar 12. Electric signals output by the first spot displacement sensor 21 and the second spot displacement sensor 22 represent vector force components of the test model 1 in the x direction and the y direction respectively. Namely, the signal of the first light spot displacement sensor 21 is only generated by the stress of the test model 1 in the x direction, and the acting force in the y direction does not influence the signal of the first light spot displacement sensor 21; the signal of the second light spot displacement sensor 22 is only generated by the stress of the test model 1 in the y direction, and the acting force in the x direction does not influence the signal of the second light spot displacement sensor 22. The balance can be effectively decoupled when forces are applied to the balance in the x and y directions of the measurement test model 1.
According to Hooke's law, when the torsion angles of the first torsion bar 7, the second torsion bar 10, the third torsion bar 12 and the fourth torsion bar 23 are in the elastic deformation range, the torsion angles are linearly related to the stress of the test model 1 in the x or y direction, namely
θ=αF，
Wherein, alpha is a constant, F is the stress component of the test model 1 in the x or y direction, and theta is the torsion angle of the torsion bar.
On a light path formed by the first laser 14, the first light spot displacement sensor 21 and the plane reflecting mirror 8 and a light path formed by the second laser 11, the second light spot displacement sensor 22 and the plane reflecting mirror 8, the rotation angle of the plane reflecting mirror 8 is linearly related to the light spot displacement of the first light spot displacement sensor 21 or the second light spot displacement sensor 22. Since the angle of rotation of the mirror 8 is equal to the torsion angle of the torsion bar, then
s=βθ，
Wherein beta is a constant, theta is the torsion angle of the torsion bar, and s is the displacement of the light spot.
Considering that the electrical signals output by the first light spot displacement sensor 21 and the second light spot displacement sensor 22 are generally linearly related to the light spot displacement, the light spot displacement sensor is used for measuring the displacement of the light spot
U=γs，
Wherein gamma is a constant, s is the displacement of the light spot, and U is an electric signal.
The electrical signal output by the balance in each force-measuring degree of freedom is linearly related to the force in the corresponding direction, i.e.
U=γβαF=kF，
Where k = γ β α is a constant.
Under actual test conditions, the coefficient k is not always constant under the influence of factors such as installation and debugging of the balance, environment and the like, so that the balance needs to be calibrated. To obtain the coefficient k of the balance in each force-measuring degree of freedom, the balance is subjected to a known calibration force in each force-measuring degree of freedom, and electrical signals in the corresponding degree of freedom are measured.
The invention adopts a calibration mechanism to obtain the coefficient k on each force measurement freedom degree. As shown in fig. 1, the calibration mechanism is used for calibrating the measurement process of the optical measurement mechanism, and is composed of an electromagnetic calibration device and a weight calibration device.
The electromagnetic calibration device is composed of a first permanent magnet array 4, a first straight lead array 5, a second permanent magnet array 17 and a second straight lead array 15. The permanent magnet array I4 and the straight wire array I5 are a first group of electromagnetic calibration devices, generate calibration force in the x direction and are used for calibrating the force measurement in the x direction; the second permanent magnet array 17 and the second straight wire array 15 are a second group of electromagnetic calibration devices, generate calibration force in the y direction and are used for calibrating the force measurement in the y direction. The two sets of calibration devices are identical in structure, and only the second set of electromagnetic calibration devices will be described below.
As shown in fig. 2, in the second set of electromagnetic calibration apparatus, the second permanent magnet array 17 is composed of a plurality of permanent magnets with the same size and parallel to each other, each two permanent magnets retain a certain air gap, and the opposite two-sided magnetic poles of each two permanent magnets are opposite to each other, thereby forming a magnetic field. Each turn of the second array of straight conductors 15 is located in the air gap of the second array of permanent magnets 17. When the direct current passes through the second direct wire array 15, the second direct wire array 15 will be acted by an ampere force, and the torque arms 3 will be acted by reaction forces with equal magnitude and opposite directions. The ampere force is the calibration force, and the direction of the ampere force is the direction of the calibration force.
In the calibration process, the angle of the torsion arm 3 around the first torsion bar 7, the third torsion bar 12 or the second torsion bar 10 and the fourth torsion bar 23 is very small, so that the relative type position of the first straight wire array 5 and the first permanent magnet array 4 and the relative type position of the second straight wire array 15 and the second permanent magnet array 17 are basically unchanged, the magnitude of the ampere force is only influenced by the magnitude of the current, and the magnitude of the ampere force is in direct proportion to the magnitude of the current. In order to generate a calibration force with high precision using an electromagnetic calibration device, the relationship between the current and the ampere force in the electromagnetic calibration device needs to be measured accurately.
The relationship between the current and the ampere force in the electromagnetic calibration device can be obtained by means of a weight calibration mechanism. As shown in fig. 1, the weight calibration mechanisms are two groups, and a first group of weight calibration mechanisms is arranged below the first group of electromagnetic calibration devices and is used for calibrating the calibration force of the electromagnetic calibration devices in the x direction; and the second group of weight calibration mechanisms are arranged below the second group of electromagnetic calibration devices and are used for calibrating the calibration force of the electromagnetic calibration devices in the y direction. The first group of weight calibration mechanisms are formed by connecting a first pull rope 24 with the torque arm 3 and a first weight tray 25, and the direction of the calibration force is changed from vertical direction to horizontal direction by using the pulley 6; and the second group of weight calibration mechanisms are formed by connecting a second pull rope 18 with the torque arm 3 and a second weight tray 19.
When the weight calibration device is used for calibrating the relation between the electrified current and the ampere force of the electromagnetic calibration device, the currents of the first straight wire array 5 and the second straight wire array 15 are cut off, and at the moment, the two groups of electromagnetic calibration devices do not work. Weights with different masses are placed in the first weight tray 25 and the second weight tray 19, and the relation U = U (G) between the weight gravity G and the electric signal U of each force measuring freedom degree is obtained.
Then, all weights in the weight tray are taken away, currents with different sizes are conducted to the first straight lead array 5 and the second straight lead array 15, the two groups of electromagnetic calibration devices begin to generate ampere force, and electric signals are output on two force measuring freedom degrees respectively. The relation between the current I and the electrical signal U can be found in U = U (I). Comparing the relations of U = U (g) and U = U (i), and considering the conversion of the gravity force arm and the ampere force arm, the relation of the current and the ampere force in the straight wire array one 5 and the straight wire array two 15 can be obtained.
After the relationship between the current and the ampere force of the two groups of electromagnetic calibration devices is obtained, in order to eliminate the influence of the mechanisms such as the first pull rope 24, the second pull rope 18, the first weight tray 25, the second weight tray 19 and the like on the balance test force measurement process, the first pull rope 24 and the second pull rope 18 can be cut off. After the first pulling rope 24 and the second pulling rope 18 are cut off, the electromagnetic calibration device is not affected, and the relationship between the current and the ampere force of the electromagnetic calibration device is unchanged.
The calibration method of the electromagnetic calibration device comprises the following steps:
(1) the electromagnetic calibration device is not electrified, weights with various masses are placed in the first weight tray 25 and the second weight tray 19, the gravity of the weights is used as calibration force, and electric signals output by the optical measurement mechanism on each force measurement degree of freedom are collected and recorded;
(2) obtaining a relation curve of weight scaling force and output electric signals on each force measuring freedom degree through the step (1);
(3) weights in the first weight tray 25 and the second weight tray 19 are taken away, the electromagnetic calibration device is electrified, and ampere force is used as calibration force;
(4) setting the current of the electromagnetic calibration device to be different values, generating corresponding calibration force by the electromagnetic calibration device, and simultaneously collecting and recording electric signals output by the optical measurement mechanism on each force measurement freedom degree;
(5) obtaining a relation curve of the electrifying current and the output electric signal of the electromagnetic calibration device on each force measuring freedom degree through the step (4);
(6) comparing the relation curves and the data in the step (2) and the step (5) to obtain a relation curve between the electrifying current and the calibration force of the electromagnetic calibration device;
(7) repeating the steps 1) to 6) for a plurality of times, fitting to obtain an average relational expression of the electrified current and the calibration force of the electromagnetic calibration device, and ending the calibration process of the electromagnetic calibration device.
The balance force measuring method comprises the following steps:
(1) mounting a test model 1 on a balance through a model support frame 2, and mounting the balance on a test section of a wind tunnel or a water tunnel;
(2) the balance is adjusted to be in a balance position by using the balance weight 16;
(3) adjusting the positions of the first light spot displacement sensor 21 and the second light spot displacement sensor 22 to enable the output electric signal to return to zero and enable the length of a laser light path to meet the requirement of a force measuring range;
(4) starting all the electromagnetic calibration devices, adjusting the current of the electromagnetic calibration devices to different values, collecting and recording the electric signals output by the optical measurement mechanism on each force measurement degree of freedom, and obtaining a relation curve between the calibration force of the electromagnetic calibration devices on each force measurement degree of freedom and the output electric signals;
(5) closing all the electromagnetic calibration devices, and entering a test stage;
(6) the test model 1 starts to work, and electric signals output by the optical measurement mechanism on each force measurement freedom degree are collected and recorded;
(7) and obtaining the vector force component in the corresponding direction through the relation curve of the electromagnetic calibration force on each force measurement freedom degree and the output electric signal.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (5)
1. A torsion balance type two-degree-of-freedom force measuring balance is characterized in that: the device comprises a balance frame mechanism, an optical measuring mechanism and a calibration mechanism; wherein,
the balance platform frame mechanism is used for decomposing vector force borne by the test model (1) into components in the horizontal direction and the vertical direction and respectively generating torsional deformation in the horizontal direction and the vertical direction;
the optical measuring mechanism is used for measuring the torsional deformation of the balance frame mechanism in the horizontal and vertical directions;
the calibration mechanism is used for calibrating the measurement process of the optical measurement mechanism;
the balance platform frame mechanism comprises a torsion arm (3), a first torsion bar (7), a second torsion bar (10), a third torsion bar (12), a fourth torsion bar (23) and a support frame;
the support frame comprises a model support frame (2), a balance fixing support frame (13), a balance moving support frame (9) and a balance central support frame (20);
the test model (1) is connected with a torque arm (3) through a model support frame (2);
a counterweight (16) is arranged on the torque arm (3) to balance the weight of the test model (1);
the torsion arm (3) is connected to a second torsion bar (10) and a fourth torsion bar (23) which are vertically arranged through a balance center support frame (20); the upper end of the second torsion bar (10) and the lower end of the fourth torsion bar (23) are connected to a balance moving support frame (9); the balance moving support frame (9) is connected to the first torsion bar (7) and the third torsion bar (12); the first torsion bar (7) and the third torsion bar (12) are connected to a balance fixing support frame (13); the balance fixing support frame (13) is arranged on the ground base and is kept stable and fixed;
the central axes of the first torsion bar (7) and the third torsion bar (12) are collinear, the central axes of the second torsion bar (10) and the fourth torsion bar (23) are collinear, and the two axes are mutually vertical and intersect at one point.
2. The torsion-scale two-degree-of-freedom force measuring balance of claim 1, wherein: the optical measuring mechanism comprises two groups of optical measuring devices, wherein a first laser (14), a first facula displacement sensor (21) and the plane reflector (8) form one group of optical measuring devices; the plane reflector (8), the second laser (11) and the second light spot displacement sensor (22) form another group of optical measuring devices;
the plane mirror (8) is arranged in the balance center support frame (20) and is positioned on a plane formed by the central axes of the first torsion bar (7), the third torsion bar (12), the second torsion bar (10) and the fourth torsion bar (23);
when the test model (1) is subjected to horizontal acting force, the torsion arm (3) rotates around the second torsion bar (10) and the fourth torsion bar (23), and the plane mirror (8) synchronously rotates in a plane vertical to the central axes of the second torsion bar (10) and the fourth torsion bar (23);
when the test model (1) is subjected to vertical acting force, the torsion arm (3) rotates around the first torsion bar (7) and the third torsion bar (12), and the plane mirror (8) synchronously rotates in a plane vertical to the central axes of the first torsion bar (7) and the third torsion bar (12);
when the test model (1) is subjected to acting forces in the horizontal and vertical directions, the torsion arm (3) and the plane reflector (8) rotate around the central axes of the second torsion bar (10) and the fourth torsion bar (23) and the central axes of the first torsion bar (7) and the third torsion bar (12), and the reflecting point on the plane reflector (8) is a fixed point, so that the balance frame mechanism can be effectively decoupled when the horizontal and vertical directions of the test model (1) are measured;
the first laser (14) and the first spot displacement sensor (21) are arranged in a horizontal plane intersecting the central axis of the first torsion bar (7) and the third torsion bar (12); the second laser (11) and the second light spot displacement sensor (22) are arranged in a plane which is perpendicular to the central axes of the first torsion bar (7) and the third torsion bar (12) and passes through the central axes of the second torsion bar (10) and the fourth torsion bar (23);
laser beams generated by the first laser (14) and the second laser (11) are respectively reflected to the first light spot displacement sensor (21) and the second light spot displacement sensor (22) by the plane reflector (8), so that light spots are subjected to displacement vibration on the photosensitive surface;
and the first light spot displacement sensor (21) and the second light spot displacement sensor (22) output electric signals and respectively represent the stress components of the test model (1) in the horizontal direction and the vertical direction.
3. The torsion-scale two-degree-of-freedom force measuring balance of claim 2, wherein: the calibration mechanism comprises an electromagnetic calibration device and a weight calibration mechanism;
the two groups of electromagnetic calibration devices are respectively arranged on the torque arm (3), and the ampere force applied to the magnetic field formed by the permanent magnet by the electrified straight lead is used as the calibration force;
the first group of electromagnetic calibration devices are composed of a permanent magnet array I (4) and a straight wire array I (5) and generate a calibration force in the horizontal direction; the second group of electromagnetic calibration devices generate a calibration force in the vertical direction by a second permanent magnet array (17) and a second straight wire array (15);
the weight calibration mechanisms are divided into two groups, and the first group of weight calibration mechanisms are arranged below the first group of electromagnetic calibration devices; the second group of weight calibration mechanisms are arranged below the second group of electromagnetic calibration devices; the two groups of weight calibration mechanisms are used for calibrating the relationship between the current and the calibration force of the electromagnetic calibration device;
the first group of weight calibration mechanisms are formed by connecting a first pull rope (24) with a torque arm (3) and a first weight tray (25), and the direction of the calibration force is changed from vertical direction to horizontal direction by using a pulley (6); and the second group of weight calibration mechanisms are formed by connecting a second pull rope (18) with a torque arm (3) and a second weight tray (19).
4. A method of calibrating the torsion-scale two degree-of-freedom force balance of claim 3, comprising the steps of:
1) the electromagnetic calibration device is not electrified, weights with various masses are placed in the weight tray I (25) and the weight tray II (19), the gravity of the weights is used as calibration force, and electric signals output by the optical measurement mechanism on each force measurement freedom degree are collected and recorded;
2) obtaining a relation curve of weight scaling force and output electric signals on each force measuring freedom degree through the step 1);
3) weights in the first weight tray (25) and the second weight tray (19) are taken away, the electromagnetic calibration device is electrified, and ampere force is used as calibration force;
4) setting the current of the electromagnetic calibration device to be different values, generating corresponding calibration force by the electromagnetic calibration device, and simultaneously collecting and recording electric signals output by the optical measurement mechanism on each force measurement freedom degree;
5) obtaining a relation curve of the electrified current and the output electric signal of the electromagnetic calibration device on each force measuring freedom degree through the step 4);
6) comparing the relation curve and the data in the step 2) and the step 5) to obtain a relation curve of the electrifying current and the calibration force of the electromagnetic calibration device;
7) and repeating the steps 1) to 6) for a plurality of times, fitting to obtain an average relational expression of the electrified current and the calibration force of the electromagnetic calibration device, and ending the calibration process of the electromagnetic calibration device.
5. A method of measuring force in a torsion-scale-type two-degree-of-freedom force measuring balance according to claim 3, comprising the steps of:
1) mounting a test model on a balance through a model support frame (2), and mounting the balance on a test section of a wind tunnel or a water tunnel;
2) adjusting the balance to a balance position by using a balance weight (16);
3) adjusting the positions of the first light spot displacement sensor (21) and the second light spot displacement sensor (22) to return the output electric signal to zero, and enabling the length of a laser light path to meet the requirement of a force measuring range;
4) starting all the electromagnetic calibration devices, adjusting the current of the electromagnetic calibration devices to different values, collecting and recording the electric signals output by the optical measurement mechanism on each force measurement degree of freedom, and obtaining a relation curve between the calibration force of the electromagnetic calibration devices on each force measurement degree of freedom and the output electric signals;
5) closing all the electromagnetic calibration devices, and entering a test stage;
6) the test model starts to work, and electric signals output by the optical measurement mechanism on each force measurement freedom degree are collected and recorded;
7) and obtaining the vector force component in the corresponding direction through the relation curve of the electromagnetic calibration force on each force measurement freedom degree and the output electric signal.
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| CN110631802B (en) * | 2019-09-29 | 2021-02-02 | 浙江海洋大学 | Torsion bar type mechanical acquisition instrument |
| CN112268681B (en) * | 2020-09-24 | 2022-10-18 | 南京理工大学 | Five-component strain balance testing device and method |
| CN112629812B (en) * | 2021-03-11 | 2021-05-14 | 中国空气动力研究与发展中心高速空气动力研究所 | Wind tunnel balance loading device |
| CN113092055B (en) * | 2021-06-09 | 2021-08-10 | 中国空气动力研究与发展中心低速空气动力研究所 | Automatic zero calibration mechanism and zero calibration method for wind tunnel side wall supporting movement mechanism |
| CN113670567B (en) * | 2021-08-24 | 2024-04-09 | 哈尔滨工业大学（深圳） | High dynamic response force measuring balance for measuring wall friction resistance and calibration method thereof |
| CN115165295A (en) * | 2022-07-13 | 2022-10-11 | 中国空气动力研究与发展中心超高速空气动力研究所 | Micro-pneumatic load measuring device and application method thereof |
| CN115389157B (en) * | 2022-07-18 | 2024-08-06 | 中国航天空气动力技术研究院 | Wind tunnel astronomical motion calibration device and method for generating step load |
| CN115046723B (en) * | 2022-08-15 | 2022-10-25 | 中国空气动力研究与发展中心高速空气动力研究所 | Loading device for preparing force measurement test and test method |
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| CN102169035B (en) * | 2010-12-22 | 2012-06-27 | 中国科学院广州能源研究所 | Torsional high-accuracy micro-thrust measuring system |
| KR101386630B1 (en) * | 2012-04-30 | 2014-04-18 | 국방과학연구소 | Overload protecting device for internal balance, apparatus for wind tunnel test having the same, bench test method for protecting device and method for bench test |
| CN204043884U (en) * | 2014-07-08 | 2014-12-24 | 中国空气动力研究与发展中心低速空气动力研究所 | A kind of test unit for the flexible thing dynamometry of low-speed wind tunnel |
| CN105372036B (en) * | 2015-12-17 | 2017-03-22 | 西北工业大学 | Multi freedom balance calibration device and balance calibration method |
| CN106442195B (en) * | 2016-11-07 | 2023-05-23 | 上海华龙测试仪器有限公司 | Mechanical testing device of test piece |
| CN106644367B (en) * | 2017-01-13 | 2023-06-16 | 中国空气动力研究与发展中心高速空气动力研究所 | Combined type high-resistance wind tunnel strain balance |
| CN106940243B (en) * | 2017-05-05 | 2023-09-22 | 山东大学 | Six-component measuring balance and model for wind tunnel experiment |
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