CN114046722A - Displacement meter - Google Patents
Displacement meter Download PDFInfo
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- CN114046722A CN114046722A CN202111187980.7A CN202111187980A CN114046722A CN 114046722 A CN114046722 A CN 114046722A CN 202111187980 A CN202111187980 A CN 202111187980A CN 114046722 A CN114046722 A CN 114046722A
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- cantilever beam
- strain
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- displacement
- supporting seat
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
- G01B7/18—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in resistance
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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Abstract
The embodiment of the application provides a displacement meter, which comprises a supporting seat; the cantilever beam is detachably and fixedly connected with the supporting seat along one end of the cantilever beam in the length direction, the other end of the cantilever beam protrudes out of the supporting seat so as to be capable of elastically deforming along the vertical direction of the cantilever beam, and the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of the displacement meter can be adjusted; the strain measuring device is used for measuring the actual strain generated by the cantilever beam driven by the vertical movement of the part to be measured; and the processing device is used for obtaining the vertical displacement of the to-be-measured part according to the actual strain, the preset strain and the vertical displacement relation function. By applying the device, the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of the displacement meter can be adjusted according to the measuring requirement, the requirement of different pieces to be measured on measuring displacement is met, and the application range of the device is widened; and the device has simple structure and is convenient to set.
Description
Technical Field
The application relates to the technical field of detection equipment, in particular to a displacement meter.
Background
The displacement meter is a sensor for measuring the structural displacement, and is widely applied to the industries of aerospace, rail vehicles, mechanical manufacturing, civil construction and the like. The common displacement meter in the engineering field has a fixed use range, and cannot be used for measuring when the displacement is larger than the range; when the displacement is far smaller than the nominal range of the displacement meter, the measurement accuracy cannot be guaranteed. In order to ensure that the measurement result is effective and accurate, the displacement meters with proper measuring ranges are selected according to specific conditions, so that various measuring range displacement meters are required to be prepared as reserves, the management pressure and the capital pressure are increased, particularly for field measurement tasks, the displacement meters with various measuring ranges are required to be carried as alternatives, and the transportation cost and the damage risk are increased. Although the displacement meter developed based on the laser equipment has high measurement precision and wide measurement range, the wide application of the displacement meter is restricted due to the factors of high cost, strict requirement on the test environment and the like. Therefore, it is necessary to design a displacement meter with simple structure, accurate measurement and convenient and fast use and capable of adjusting the measuring range to service the displacement measurement work.
Disclosure of Invention
The embodiment of the application provides a displacement meter to solve the problem that the measuring range of the existing displacement meter can not be adjusted.
In order to achieve the above purpose, the present application provides the following technical solutions:
a displacement meter, comprising:
a supporting seat;
one end of the cantilever beam along the length direction is fixedly connected with the supporting seat in a detachable mode, the other end of the cantilever beam protrudes out of the supporting seat to be capable of elastically deforming along the vertical direction of the cantilever beam, and the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of the displacement meter can be adjusted;
the strain measuring device is used for measuring the actual strain generated by driving the cantilever beam when the part to be measured moves vertically;
and the processing device is used for obtaining the vertical displacement of the to-be-measured part according to the actual strain, the preset strain and the vertical displacement relation function.
Preferably, the method further comprises the following steps:
and the measuring connecting piece is fixed at one end of the cantilever beam, which is far away from the supporting seat, is used for being fixed with the piece to be measured and moves along with the upward and downward vertical movement of the measuring connecting piece.
Preferably, the measuring connecting piece is vertically arranged at the edge of the end part of the cantilever beam, and a threaded hole is formed in the cantilever beam;
the measuring connecting piece is a measuring thimble, the top of the measuring thimble is provided with an installation groove, and a universal ball is arranged in the installation groove; the bottom of the measuring thimble is provided with an external thread for fixing with the threaded hole.
Preferably, the ball transfer unit is a magnetic ball transfer unit.
Preferably, the cantilever beam is a cantilever beam with a uniform cross section;
the processing device is according to the formula
Calculating the maximum measuring range w under the extension length L of the cantilever beammax；
Wherein σsPresetting a yield limit coefficient, k, for a beam material of the cantilever beamsFor a predetermined safety factor, h isThe beam section thickness of the cantilever beam, E is the elastic modulus, rho is the beam material density of the cantilever beam, and g is the gravitational acceleration.
Preferably, the processing device is specifically configured to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset first strain and a vertical displacement relation function;
the preset relation function of the first strain and the vertical displacement is
Wherein epsilongAnd in order to actually strain, w is vertical displacement, S is the distance between the strain measuring device and the fixed pivot of the supporting seat, L is the extension length of the cantilever beam, h is the beam section thickness of the cantilever beam, and a is the length of the measuring connecting piece.
Preferably, the processing device is specifically configured to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset second strain and a vertical displacement relation function;
the preset relation function of the second strain and the vertical displacement is wt＝k·εt(ii) a Wherein epsilongFor actual strain, wtAnd k is a preset coefficient corresponding to the extension length of the cantilever beam at present for vertical displacement.
Preferably, the strain measuring device includes:
the two resistance-type strain gauges are respectively and correspondingly fixed on the upper surface and the lower surface of the cantilever beam at the same position of the central line; the wire is connected with the two resistance-type strain gauges to form an arm-adjacent half-bridge circuit;
and the temporary arm half-bridge circuit is connected into the data acquisition unit to form a full-bridge circuit to measure actual strain.
Preferably, the support seat comprises:
a base plate;
the side plates are arranged in parallel and are respectively fixed on the bottom plate, and the bottom plate and the side plates form a limiting cavity; part of the cantilever beam is positioned in the limiting cavity and can slide along the length direction of the limiting cavity;
the fastener is fixed on the side plate and positioned above the cantilever beam, and the fastener is used for detachably and fixedly connecting the cantilever beam with the bottom plate.
Preferably, the fastener comprises:
the two ends of the L-shaped plate along the length direction respectively correspond to and are fixed with the side plates, the L-shaped plate comprises a first plate body and a second plate body, the first plate body and the second plate body are vertically arranged, and the first plate body is arranged in parallel to the bottom plate;
the first plate body is provided with a first mounting groove along the length direction of the supporting seat, the first mounting groove penetrates through the second plate body, and the first mounting groove and the second plate body form a limiting hole for the cantilever beam to penetrate through;
the cover plate is fixed above the first plate body, and a second mounting groove for mounting the cantilever beam is formed in the cover plate;
one end of each threaded fastener penetrates through the cover plate and the first plate body in sequence along the vertical direction, and the other end of each threaded fastener protrudes out of the first plate body and abuts against the cantilever beam.
Preferably, the cantilever beam is provided with a plurality of measuring range marking layers along the length direction, so that the extending length of the cantilever beam corresponds to the maximum measuring range.
The displacement meter provided by the embodiment of the application comprises a supporting seat; the cantilever beam is detachably and fixedly connected with the supporting seat along one end of the cantilever beam in the length direction, the other end of the cantilever beam protrudes out of the supporting seat so as to be capable of elastically deforming along the vertical direction of the cantilever beam, and the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of the displacement meter can be adjusted; the strain measuring device is used for measuring the actual strain generated by the cantilever beam driven by the vertical movement of the part to be measured; and the processing device is used for obtaining the vertical displacement of the to-be-measured part according to the actual strain, the preset strain and the vertical displacement relation function.
Compared with the prior art, the displacement meter provided in the embodiment of the application has the following technical effects:
firstly, one end of a cantilever beam along the length direction is fixedly connected with a supporting seat in a detachable mode, the other end of the cantilever beam protrudes out of the supporting seat and can elastically deform along the vertical direction of the cantilever beam, the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of a displacement meter can be adjusted according to measuring requirements, the measuring length requirements of different pieces to be measured are met, and the application range of the device is widened; the device has simple structure and is convenient to set;
and secondly, bidirectional displacement measurement can be carried out, and the measuring range is increased while the length of the cantilever beam is not increased.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic structural diagram of a displacement meter according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of an exploded structure of a displacement meter according to an embodiment of the present disclosure;
FIG. 3 is a schematic illustration of an equi-sectioned cantilever beam provided in an embodiment of the present application;
FIG. 4 is a schematic view illustrating a deflection angle of a measurement thimble according to an embodiment of the present disclosure;
FIG. 5 is a schematic circuit diagram of a strain measurement circuit according to an embodiment of the present disclosure;
FIG. 6 is a wiring diagram of a strain measurement circuit provided in an embodiment of the present application;
fig. 7 is a schematic view of a measurement operation of the displacement meter according to the embodiment of the present application.
The drawings are numbered as follows:
the device comprises a supporting seat 1, a cantilever beam 2, a measuring connecting piece 3 and a resistance type strain gauge 4;
a bottom plate 12, a side plate 11 and a fastener 13;
l-shaped plate 131, cover plate 132, threaded fastener 133;
a displacement gauge 100.
Detailed Description
The embodiment of the invention discloses a displacement meter, which aims to solve the problem that the measuring range of the conventional displacement meter cannot be adjusted.
In order to make the technical solutions and advantages of the embodiments of the present application more apparent, the following further detailed description of the exemplary embodiments of the present application with reference to the accompanying drawings makes it clear that the described embodiments are only a part of the embodiments of the present application, and are not exhaustive of all embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
Referring to fig. 1-2 and 7, fig. 1 is a schematic structural diagram of a displacement meter according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of an exploded structure of a displacement meter according to an embodiment of the present disclosure; fig. 7 is a schematic view of a measurement operation of the displacement meter according to the embodiment of the present application.
In a specific embodiment, the present application provides a displacement meter 100, which includes a support base 1, a cantilever beam 2, a strain measuring device and a processing device. The supporting seat 1 may be configured as a U-shaped housing or a supporting plate, and one end of the supporting seat in the length direction is an open structure for mounting the cantilever beam 2 and providing support thereto, and it can be understood that the contact point of the supporting seat 1 and the cantilever beam 2 serves as a fixed pivot. Cantilever beam 2 is along length direction's one end and supporting seat 1 detachable fixed connection, if fixed through threaded fastener 133, the length that cantilever beam 2 stretches out supporting seat 1 can be adjusted, and after adjusting cantilever beam 2's the extension length, accessible threaded fastener 133 is fixed cantilever beam 2 and supporting seat 1. Cantilever beam 2 can take place elastic deformation along its vertical to measure the vertical displacement of the part to be measured. The strain measuring device is used for measuring the actual strain generated by driving the cantilever beam 2 when the part to be measured moves vertically. The strain gauge may be configured as a resistive strain gauge 4, and the resistive strain gauge 4 is fixed on the surface of the cantilever beam 2, such as by bonding or other fixing means. In other embodiments, the specific structure of the strain measuring device may be set as required, and is within the scope of the present application. The processing device can be specifically a processor, a PLC controller and other structures, and obtains the vertical displacement of the to-be-measured piece according to the actual strain, the preset strain and the vertical displacement relation function.
Compared with the prior art, the displacement meter 100 provided in the embodiment of the present application has the following technical effects:
one end of the cantilever beam 2 along the length direction is detachably and fixedly connected with the supporting seat 1, the other end of the cantilever beam protrudes out of the supporting seat 1 and can elastically deform along the vertical direction of the cantilever beam 2, the length of the cantilever beam 2 extending out of the supporting seat 1 can be adjusted, so that the measuring range of the displacement meter 100 can be adjusted according to the measuring requirement, the measuring length requirements of different pieces to be measured are met, and the application range of the device is widened; and the device has simple structure and is convenient to set.
In one embodiment, in order to realize the bidirectional displacement measurement of the displacement meter 100, the present application further includes a measuring connecting member 3, the measuring connecting member 3 is fixed to an end of the cantilever beam 2 away from the supporting base 1, the measuring connecting member 3 is used for being fixed to a member to be measured, and the measuring connecting member 3 and the member to be measured can be fixed by adhesion so as to be capable of moving along with the upward and downward vertical movement of the measuring connecting member 3; when the piece to be measured moves downwards along the vertical direction, the cantilever beam 2 is pressed to move downwards together; when the piece to be measured moves upwards in the vertical direction, the piece to be measured drives the cantilever beam 2 to move upwards in the vertical direction due to the fact that the measuring connecting piece 3 and the piece to be measured are magnetically adsorbed, so that bidirectional displacement measurement of the piece to be measured is achieved, the measuring range of the displacement meter 100 is improved, and the universality of the device is improved.
Preferably, the measuring attachment 3 is located at the end of the cantilever beam 2 such that the distance of the measuring attachment 3 from the fixed fulcrum corresponds to the extension of the cantilever beam 2. In particular, the measuring connection 3 is provided perpendicularly to the end edge of the cantilever beam 2, thereby reducing the calculation error of the extension length of the cantilever beam 2. Be equipped with the screw hole on the cantilever beam 2, accessible threaded fastener 133 will measure connecting piece 3 and cantilever beam 2 and fix. In one embodiment, the measuring connecting piece 3 is a measuring thimble, the top of the measuring thimble is provided with an installation groove, a universal ball is arranged in the installation groove, and the universal ball can rotate along the circle center in the installation groove; the bottom of the measuring thimble is provided with an external thread for being fixed with the threaded hole, so that the structure of the device is simplified, and the production cost is reduced. In order to simplify the device and to enable the measuring connection part 3 and the part to be measured to be fixed, the universal ball is a universal magnetic ball, and the part to be measured is fixed with the metal part to be measured through magnetic force.
The cantilever beam 2 can be set to low carbon steel and be the equal cross-section roof beam, and the test connecting piece rigidity is fixed at the front end of cantilever beam 2, and supporting seat 1 is the metal square tube form, has certain rigidity, provides the protection when returning to spacing intracavity for cantilever beam 2 to and provide fixed pivot for cantilever beam 2.
As shown in fig. 3, fig. 3 is a schematic view of an equi-section cantilever beam 2 provided in the embodiment of the present application; in a specific embodiment, the cantilever beam 2 is a cantilever beam 2 with a uniform cross section, such as a rectangular cross section in the vertical direction. In particular, the processing means are according to the formula
Calculating the maximum measuring range w under the extension length L of the cantilever beam 2max(ii) a Wherein σsTo preset the yield limit coefficient, ksIn order to preset a safety factor, h is the beam section thickness of the cantilever beam 2, E is the elastic modulus, rho is the beam material density of the cantilever beam 2, and g is the acceleration of gravity.
Wherein, when the cantilever beam 2 with the uniform cross section is acted by vertical downward force at the free end, the maximum stress appears on the upper surface and the lower surface of the beam at the fixed pivot. Using (preset yield coefficient σ)sPreset safety factor ks) As a check criterion, taking into account the torque M generated by the force fmaxTorque M generated by the weight of the beamZShould satisfy
Wherein σfIs a force fStress, σ, produced by the beam surface at the fixing point under the actionzObtaining the maximum measuring range w of the displacement meter according to the formula (1) for the stress generated by the self weight of the beam on the surface of the beam at the fixed pointmaxFunction of the extension length L of the cantilever beam 2
According to the formula (2), after the measuring range of the displacement meter is determined, the yield limit, the Young modulus and the density can be changed by selecting a beam material; the design of the displacement cantilever beam 2 is carried out by changing the outline thickness and the length of the beam.
On the basis of the foregoing embodiments, the processing apparatus is specifically configured to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset first strain and a vertical displacement relation function;
a predetermined first strain and vertical displacement relationship function of
Wherein epsilongFor actual strain, w is vertical displacement, S is the distance between the strain measurement device and the fixed pivot of the support seat 1, L is the extension length of the cantilever beam 2, h is the beam section thickness of the cantilever beam 2, and a is the length of the measurement connecting piece 3.
The specific derivation process is as follows: because the downward deformation of the beam is consistent with the upward deformation calculation method, the downward deformation is taken as an example for explanation, b is the width of the section of the beam, f is the vertical downward force at the thimble, and w isBWhich is the downward deflection of the cantilever beam 2 under the force f.
Since the deflection of a beam is much smaller than its span (beam length), i.e. L>>wBDownward deflection w of cantilever beam 2 under force fBThe product of area inertia I is
Obtained according to formula (4) and formula (5)
Bending resistance section modulus
Therefore, the stress sigma at the position of the center line S of the lower surface of the cantilever beam 2gAnd strain epsilongIs composed of
Wherein E is the Young modulus of the cantilever beam 2 material, and the formula (6) is substituted into the sigmagAnd εgIn the method, the relation between the beam displacement and the strain at the S position is obtained
Wherein, wBWhen "-", it means downward displacement; w is aBAnd a "+" indicates an upward shift.
As shown in fig. 4, fig. 4 is a schematic view illustrating a deflection angle of a measurement thimble according to an embodiment of the present disclosure; further, when the measuring thimble is acted by a downward force f, the cantilever beam 2 generates downward deflection, the measuring thimble generates a deflection angle, and the length of the measuring thimble is known as a, the relation between the actual displacement of the to-be-measured element and the measured displacement of the cantilever beam 2 is obtained as
d1＝d2+ a (1-cos θ) … … … … … … … … … … … … … … … … … … formula (8)
When the cantilever beam 2 displaces downwards, the difference value generated by the rotation angle of the measuring thimble is a (1-cos theta), and theta is the pointer deflection angle, namely the rotation angle of the cantilever beam 2 at the measuring thimble, therefore
The downward displacement w at the measuring point of the thimble of the cantilever beam 2 and the strain epsilon at the S position on the beam are obtained by integrating the formula (7), the formula (8) and the formula (9)gRelation formula
When the vertical downward force is applied to the measuring thimble, the vertical displacement at the measuring thimble is positively correlated with the strain of the measuring point, and when the size parameter of the beam is known, the strain epsilon at the S position is measuredgAnd the vertical downward displacement of the measuring thimble can be obtained.
On the basis of the foregoing embodiments, the processing apparatus is specifically configured to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset second strain and a vertical displacement relation function;
a predetermined second strain and vertical displacement relationship function of
wt＝k·εt… … … … … … … … … … … … … … … … … … … … … … … formula (10);
wherein the content of the first and second substances,
for actual strain, wtAnd k is a preset coefficient corresponding to the extension length of the current cantilever beam 2 for vertical displacement.
Based on the assumption that the beam deflection is far smaller than the beam length, a proportional relation between strain and displacement is obtained, and a nonlinear condition can occur actually; all the parameters are set as theoretical values, and factors such as processing errors, uneven materials, unstable product performance of different batches and the like are not considered. It is necessary to perform multiple long strain-displacement acquisitions for each range before use. The deflection curve and deflection change of the beam are continuous, so that the downward displacement and strain of the beam are also continuous and free of singularity, the strain-displacement curve of each measuring range of the displacement meter 100 is obtained through multi-step strain-displacement corresponding data fitting, the curve slope corresponding to each strain value under the using condition of each measuring range is the strain-displacement coefficient, and the independent characteristic of each displacement meter 100 is obtained.
When the range (w-, w +) is set for the displacement meter, according to the formula (10), the test strain epsilon is acquired according to the fitting strain-displacement curve of the range and the known fitting strain-displacement curvetThe displacement w can be obtainedt。
A fitting-displacement curve is defined in each measuring range, and strain-displacement conversion coefficients of different measuring points are obtained by using the fitting curve, so that the test result is more accurate.
In one embodiment, the strain measurement device comprises two resistance-type strain gauges 4 and a data acquisition unit, wherein the two resistance-type strain gauges 4 are respectively and correspondingly fixed on the upper surface and the lower surface of the cantilever beam 2 at the same position of the central line; the two resistance type strain gauges 4 are connected with a lead to form an arm-adjacent half-bridge circuit; the arm-facing half-bridge circuit is connected with the data acquisition unit to form a full-bridge circuit for measuring actual strain.
In another embodiment, four resistive strain gauges 4 may be provided, and the measurement is performed by a full bridge circuit, which is within the protection scope of the present application.
The supporting seat 1 comprises a bottom plate 12, a fastening piece 13 and a group of side plates 11 which are arranged in parallel. The side plates 11 are respectively fixed on the bottom plate 12, and the bottom plate 12 and the side plates 11 form a limiting cavity; the cantilever beam 2 is positioned in the limiting cavity and can slide along the length direction of the limiting cavity; the side plate 11 is perpendicular to the bottom plate 12, the supporting seat 1 is of a U-shaped structure, one end of the U-shaped structure is of an open structure, the other end of the U-shaped structure is of a closed structure, and the cantilever beam 2 slides in the limiting cavity. The fastener 13 is preferably fixed on the side plates 11, both ends of the fastener 13 in the length direction are respectively fixedly connected with the side plates 11 on both sides, meanwhile, the fastener 13 is arranged above the cantilever beam 2, after the extension length of the cantilever beam 2 is adjusted, the cantilever beam 2 and the supporting seat 1 are fixed through the fastener 13, and the fastener 13 is used for detachably and fixedly connecting the cantilever beam 2 and the bottom plate 12, for example, fixing is realized through the threaded fastener 133.
Specifically, 2 resistance strain gages 4 are pasted to the upper and lower surface S department position of elastic beam central line and constitute and face arm half-bridge circuit, insert strain acquisition system and form the full-bridge circuit and carry out the strain measurement, can get rid of the influence of temperature variation to strain measurement, improved measurement accuracy again. The measuring circuit of the present invention is shown in fig. 5-6, and fig. 5 is a schematic circuit diagram of a strain measuring circuit provided in an embodiment of the present application; FIG. 6 is a wiring diagram of a strain measurement circuit provided in an embodiment of the present application; wherein, A1 and A2 represent strain gauges on the front and back sides of the beam, E is bridge circuit output voltage, and E is bridge circuit input voltage; a, B and C respectively represent 3 signal output wires of the displacement meter and are respectively connected to a point a, a point B and a point C of a circuit of the data acquisition system. The data acquisition device is connected with a computer, acquires strain change generated by the invention, and obtains a displacement measurement value through calculation.
Because a temporary arm half-bridge circuit is used, the difference value of strains of 2 strain gages is acquired, and the strain value epsilon of displacement calculation is carried outtIs composed of
Specifically, the fastener 13 includes an L-shaped plate 131, a cover plate 132, and a plurality of threaded fasteners 133. L shaped plate 131 corresponds and fixes with curb plate 11 respectively along length direction's both ends, and L shaped plate 131 includes first plate body and second plate body, and first plate body and second plate body set up perpendicularly, and first plate body is on a parallel with bottom plate 12 and sets up, and the preferred integral type of the two sets up to in production and processing. The first plate body is provided with a first mounting groove along the length direction of the supporting seat 1, the first mounting groove penetrates through the joint of the second plate body and the first plate body along the length direction, so that the first mounting groove and the second plate body form a limiting hole for the penetration of the cantilever beam 2, the cantilever beam 2 penetrates through the limiting hole and is arranged in the first mounting groove, the first plate body and the cover plate 132 are respectively provided with a mounting hole, and the hole depth direction of the mounting hole is perpendicular to the cantilever beam 2; one end of the threaded fastener 133 is located in the mounting hole, and the other end protrudes out of the mounting hole to abut against the cantilever beam 2. The cover plate 132 is fixed above the first plate, and the cover plate 132 is provided with a second mounting groove for mounting the cantilever beam 2. The device is simple in structure and convenient to set.
It can be understood that, leave the interval between the first plate body of L shaped plate 131 and bottom plate 12, cantilever beam 2 realizes fixedly through first plate body and apron 132, this kind of setting mode for cantilever beam 2 all is in unsettled state along length direction's both ends, and fixed pivot only is for the junction with L shaped plate 131, prevents that the too big strain of bearing area to cantilever beam 2 from causing the interference, improves measurement accuracy.
In another embodiment, the cantilever beam 2 is provided with a plurality of measurement distance marking layers along the length direction, so as to correspond the extending length of the cantilever beam 2 with the maximum measurement distance. At this time, the coefficient of the preset relation function of the strain and the vertical displacement can be determined according to the selected maximum measuring range and the extension length, and the vertical displacement can be directly calculated.
In a specific embodiment, the following illustrates displacement meter adjustment, and the parameters may be changed according to specific needs.
TABLE 1 Displacement gauge parameters
| Item | Numerical value |
| The elastic beam extends to the maximum state and extends to the total length L | 275mm |
| Thickness h of elastic beam | 1.5mm |
| Width b of elastic beam | 20mm |
| Length of thimble a | 15mm |
| Distance S from strain gage to fixed support point when beam is maximally extended | 170mm |
| Elastic beam material | Low carbon steel |
| Modulus of elasticity E | 200Gpa |
| Yield limit σs | 345Mpa |
| Low carbon steel density rho | 7.85g/cm3 |
| Factor of safety ks | 1.1 |
Substituting the displacement meter parameters into the formula (2) and ensuring that the distance between the center of the strain gauge and the fixed pivot is at least 20mm when the cantilever beam 2 retracts, avoiding the damage of the strain gauge and the stress concentration from influencing the strain result, and calculating the maximum one-way range w of the whole beam extendingmaxMinimum one-way range w of the sum beam shrinking to the minimum stateminWherein w ismax＝50.75mm，wmin＝10.81mm。
The following lists the strain-displacement relationship between the maximum and minimum extension lengths of the elastic beam to obtain a one-way 50mm range and a one-way 10mm range, where wBWhen "-", it means downward displacement; when the number is + or the like, the display screen is,represents an upward displacement:
50mm range site: when the beam stretches out to the maximum, the parameters of the displacement meter shown in the table 1 are driven into the formula (3), and the relation between the displacement and the strain is obtained
w＝-88.029εt+0.015[1-cos(-16.139·εt)]
10mm range site: when the beam stretches out to the maximum, the parameters of the displacement meter shown in the table 1 are driven into the formula (3), and the relation between the displacement and the strain is obtained
w＝-8.267εt+0.015[1-cos(-0.689·εg)]
The specific examples of the maximum range and the minimum range are as above, the extension length of the elastic beam can be adjusted between 275 mm-125 mm when in use, the corresponding displacement range is adjusted between 50 mm-10 mm, and the extension beam length is input into a formula (3) to be calculated to obtain a strain-displacement relation; or fixing several measuring ranges, painting marks on the elastic beam after calculation, and directly using the strain-displacement relationship calculated in advance to test.
The device can realize adjustable measuring range in a certain range, and selects a proper measuring range according to the test requirement, so that the test data is more accurate. Compared with the unidirectional displacement measurement of the existing cantilever beam 2 type displacement meter, the bidirectional displacement measurement is realized by adding the powerful magnetic ball, and the measuring range is increased by 100%.
The displacement meter can change each parameter according to the principle, and can be manufactured to be applicable to measuring ranges, materials and testing environments as required. If the whole tested structure is used as an elastic beam, acquiring the measurement quantity of the structure; and selecting proper elastic beam materials for measurement and the like according to a design principle for a test task with special test environment requirements. Meanwhile, the principle of the application is simple and clear, the functions of all components and the functions of various correlation coefficients on the system are explained in detail, the components can be selected and replaced according to the user, and the operability is high.
The displacement measuring device can be applied to displacement measurement in narrow space. The requirement on installation space in the displacement measurement direction is small, and the displacement measuring device can be used for measuring the displacement between the slits. It should be noted that, if the object to be measured is a non-metal object to be measured, a metal sheet is adhered to the measuring position, and the metal sheet is matched with a strong magnetic bead to be closely magnetically attracted on the surface of the object to be measured, so that bidirectional measurement is realized. The strain sensor can be used in cooperation with any acquisition system capable of acquiring strain data, and has strong applicability to the acquisition system.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (11)
1. A displacement meter, comprising:
a supporting seat;
one end of the cantilever beam along the length direction is fixedly connected with the supporting seat in a detachable mode, the other end of the cantilever beam protrudes out of the supporting seat to be capable of elastically deforming along the vertical direction of the cantilever beam, and the length of the cantilever beam extending out of the supporting seat can be adjusted, so that the measuring range of the displacement meter can be adjusted;
the strain measuring device is used for measuring the actual strain generated by driving the cantilever beam when the part to be measured moves vertically;
and the processing device is used for obtaining the vertical displacement of the to-be-measured part according to the actual strain, the preset strain and the vertical displacement relation function.
2. The displacement gauge of claim 1, further comprising:
and the measuring connecting piece is fixed at one end of the cantilever beam, which is far away from the supporting seat, is used for being fixed with the piece to be measured and moves along with the upward and downward vertical movement of the measuring connecting piece.
3. The displacement gauge according to claim 2, wherein the measuring connector is vertically provided at an end edge of the cantilever beam, and the cantilever beam is provided with a threaded hole;
the measuring connecting piece is a measuring thimble, the top of the measuring thimble is provided with an installation groove, and a universal ball is arranged in the installation groove; the bottom of the measuring thimble is provided with an external thread for fixing with the threaded hole.
4. A displacement meter according to claim 3, wherein the ball transfer is a magnetic ball transfer.
5. The displacement gauge of claim 1, wherein the cantilever beam is a constant cross-section cantilever beam;
the processing device is according to the formula
Calculating the maximum measuring range w under the extension length L of the cantilever beammax；
Wherein σsPresetting a yield limit coefficient, k, for a beam material of the cantilever beamsAnd h is the beam section thickness of the cantilever beam, E is the elastic modulus, rho is the beam material density of the cantilever beam, and g is the gravity acceleration.
6. Displacement gauge according to any one of claims 2 to 4, characterized in that said processing means are particularly adapted to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset first strain and a vertical displacement relation function;
the preset relation function of the first strain and the vertical displacement is
Wherein epsilongAnd in order to actually strain, w is vertical displacement, S is the distance between the strain measuring device and the fixed pivot of the supporting seat, L is the extension length of the cantilever beam, h is the beam section thickness of the cantilever beam, and a is the length of the measuring connecting piece.
7. Displacement gauge according to any one of claims 2 to 4, characterized in that said processing means are particularly adapted to:
obtaining the vertical displacement of the to-be-measured part according to the actual strain, a preset second strain and a vertical displacement relation function;
the preset relation function of the second strain and the vertical displacement is wt＝k·εt(ii) a Wherein epsilongFor actual strain, wtAnd k is a preset coefficient corresponding to the extension length of the cantilever beam at present for vertical displacement.
8. The displacement gauge of claim 1, wherein the strain measuring device comprises:
the two resistance-type strain gauges are respectively and correspondingly fixed on the upper surface and the lower surface of the cantilever beam at the same position of the central line; the wire is connected with the two resistance-type strain gauges to form an arm-adjacent half-bridge circuit;
and the temporary arm half-bridge circuit is connected into the data acquisition unit to form a full-bridge circuit to measure actual strain.
9. The displacement gauge of claim 1, wherein the support base comprises:
a base plate;
the side plates are arranged in parallel and are respectively fixed on the bottom plate, and the bottom plate and the side plates form a limiting cavity; part of the cantilever beam is positioned in the limiting cavity and can slide along the length direction of the limiting cavity;
the fastener is fixed on the side plate and positioned above the cantilever beam, and the fastener is used for detachably and fixedly connecting the cantilever beam with the bottom plate.
10. The displacement gauge of claim 9, wherein the fastener comprises:
the two ends of the L-shaped plate along the length direction respectively correspond to and are fixed with the side plates, the L-shaped plate comprises a first plate body and a second plate body, the first plate body and the second plate body are vertically arranged, and the first plate body is arranged in parallel to the bottom plate;
the first plate body is provided with a first mounting groove along the length direction of the supporting seat, the first mounting groove penetrates through the second plate body, and the first mounting groove and the second plate body form a limiting hole for the cantilever beam to penetrate through;
the cover plate is fixed above the first plate body, and a second mounting groove for mounting the cantilever beam is formed in the cover plate;
one end of each threaded fastener penetrates through the cover plate and the first plate body in sequence along the vertical direction, and the other end of each threaded fastener protrudes out of the first plate body and abuts against the cantilever beam.
11. The displacement gauge of any of claims 1-10, wherein the cantilever beam is provided with a plurality of measurement indicia layers along its length to correspond the cantilever beam's extended length to the maximum measurement range.
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