CN103994715B - Contracting position, footpath minimum diameter measurement apparatus and measuring method after tensile sample fracture - Google Patents

Abstract

The present invention relates to contracting position, footpath minimum diameter measurement apparatus and measuring method after tensile sample fracture, measurement apparatus includes band location bar and measures resistance-strain type U-shaped sensor, U-bracket, the standard of some standard cylinders and the data collecting instrument equipped with Survey Software of the clamping edge of a knife.Sensor is arranged on standard cylinder or tension failure sample under the cooperation of location bar and support, will pass to data collecting instrument containing the measurement signal of normal diameter value or contracting position, sample footpath minimum diameter value and measurement clamping knife edge contact side-play amount；The calibration algorithm of Survey Software provides diameter fitting formula, and eliminates the contact deflection error caused because of each standard cylinder diameter difference；The Measurement Algorithm of Survey Software provides the diameter value of sample, and eliminates the contact deflection error caused because of specimen finish difference.

Description

Contracting position, footpath minimum diameter measurement apparatus and measuring method after tensile sample fracture

Technical field

The present invention relates to one have no progeny diameter measuring device and method, in material mechanical performance is tested, the measurement of contracting position, footpath minimum diameter after the metal stretching sample fracture of circular section, the measurement of curve variable cross-section fatigue testing specimen central cross section diameter and the measurement of the circular shaft-type parts diameter such as axle that bus is curve and Step Shaft, belong to sensor, mechanical test technology and mechanical measurement technique field.

Background technology

In material during tensile mechanical property test, in order to obtain the contraction percentage of area of material, need to measure the minimum diameter at contracting position, footpath after sample fracture, commonly use slide gauge at present and measure.The resolving power of slide gauge is generally 0.02 millimeter, and measurement data is readily incorporated manual operation error, and its measuring method is not suitable for connecting data collecting instrument.Double cantilever beam formula measuring apparatus of diameter (CN101329159 disclosed " a kind of resistor strain type apparatus for measuring diameter and using method thereof " and " analysis of double cantilever beam diameter measurement sensor performance ", journal of Zhejiang university engineering version, Vol.46, No.6, Jun.2012,1060-1066) there is the resolving power less than 0.002 millimeter, green diameter and the diameter of other similar uiform section circular shaft-type parts of material tensile sample can be measured, certainty of measurement is not affected by manual operation factor, is suitable for connecting data collecting instrument.But, this measuring instrument is limited due to the sample localization method by being used, and is not suitable for measuring the minimum diameter at contracting position, footpath after metal stretching sample fracture, and there is contact deflection error.Contact deflection error refers to the tested sample for different-diameter, the measurement error caused because measurement blade is inconsistent with the contact point of sample.

Summary of the invention

The purpose of the present invention, is for the device and method of contracting position, footpath minimum diameter after a kind of measurement tensile sample fracture that can eliminate contact deflection error of material mechanical performance test offer.

After the tensile sample fracture of the present invention, contracting position, footpath minimum diameter measurement apparatus includes sensor, support, compression spring, standard and data collecting instrument；

Sensor has a U-shaped elastomer, two sword blocks, a locating dowel, a guide rod and four pieces of single shaft strain ga(u)ge R₁、R₂、R₃And R₄；U-shaped elastomer shape is symmetrical, and its structure includes pedestal B and is fixed on the left Cantilever Beams of Variable Cross Section B at pedestal B two ends₁With right Cantilever Beams of Variable Cross Section B₂, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Cross section be rectangle, and be divided into head ac and cervical region ce two sections from free end a to root e, the cross-sectional area of head ac section is more than the cross-sectional area of cervical region ce section, and the axes O of U-shaped elastic body base B is machined with a cylindrical hole, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Respectively being machined with a rectangular through-hole at free end a, the two rectangular through-hole is in coaxial position；The structure of each sword block is divided into triangular head C₁With rectangle root C₂Two sections, triangular head C₁The rectilinear edge that front end is sword block；The top of locating dowel is triangle, and the top of triangle is the rectilinear edge of the locating dowel being perpendicular to mast axis, and the bottom of locating dowel is by lower surface E₁Rise and be machined with female thread along mast axis；The structure of guide rod is divided into upper, middle and lower segment, epimere to be threaded, and stage casing is uiform section circular shaft, and hypomere is cylindrical flat cap, and the diameter in stage casing is more than the diameter of epimere, and stage casing forms the step surface E being perpendicular to guide rod axis at the section being connected with epimere₂；Two sword blocks are by its rectangle root C₂With left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The interference fit of rectangular through-hole, be inlaid in left Cantilever Beams of Variable Cross Section B respectively₁With right Cantilever Beams of Variable Cross Section B₂On, and it is in the inner side of U-shaped elastomer；The rectilinear edge of two sword blocks is parallel to each other, and constitutes the measurement clamping cutting edge of sensor；Single shaft strain ga(u)ge R₁And R₂It is respectively adhered on left Cantilever Beams of Variable Cross Section B₁Inside and outside cervical region ce, its grid axle and left Cantilever Beams of Variable Cross Section B₁Axis parallel；Single shaft strain ga(u)ge R₃And R₄It is respectively adhered on right Cantilever Beams of Variable Cross Section B₂Inside and outside cervical region ce, its grid axle and right Cantilever Beams of Variable Cross Section B₂Axis parallel；Four pieces of strain ga(u)ge R₁、R₂、R₃And R₄Full-bridge circuit is connected into by wire；

Support is U-shaped structure, symmetrical shape；Centre in frame bottom, axes O along support is coaxially machined with the cylindrical hole on a rectangular channel and a support, rectangular channel is positioned at the inner side of support U-shaped structure, and it is through along the direction vertical with the middle face of support, in the upper end of support two-arm, be respectively machined with a V-shaped groove, the two V-shaped groove shape with towards identical, and it being in coaxial position, its axis is positioned at the middle face of support；

Guide rod is through the cylindrical hole in cylindrical hole, compression spring and the U-shaped elastic body base B axes O on frame bottom support, and U-shaped elastomer is coaxial with support, and the middle face of U-shaped elastomer is mutually perpendicular to the middle face of support；Guide rod epimere screw thread screws with the female thread of the locating dowel bottom being positioned at inside U-shaped elastomer, locating dowel lower surface E₁Upper surface E with U-shaped elastic body base B₃Compression fit, the step surface E in guide rod stage casing₂Lower surface E with U-shaped elastic body base B₄Compression fit；Compression spring is positioned at the stage casing of guide rod, its two ends contact with U-shaped elastomer and support respectively, the cylindrical flat cap of guide rod hypomere props up frame bottom lower surface, being slidably matched and being slidably matched of rectangular channel of pedestal B two sides and frame bottom of U-shaped elastomer of guide rod stage casing and the cylindrical hole on frame bottom support, collectively form a pair along sensor and the guiding rail mechanism in support common axis O direction, sensor is made to have the one-movement-freedom-degree along the two common axis O direction relative to support, simultaneously, there is certain fit clearance in this guide rail mechanism, sensor is made to have the small degree of freedom rotated around the two common axis O relative to support；The rectilinear edge of locating dowel is positioned at below sword block, and coplanar, vertical with the rectilinear edge of two sword blocks；

Standard is made up of standard cylinder and datum diameter rule of some different-diameters, the diameter value d of datum diameter rule₀It is defined as datum diameter；Quantity n >=4 of standard cylinder；The diameter d of standard cylinder₁、d₂..., d_nBy order arrangement from small to large, minimum diameter value d therein₁Primary leading s more than two sword blocks of sensor；The diameter value d of datum diameter rule₀Meet relation d₁<d₀<d_n；

Data collecting instrument includes strain signal collection-modulate circuit and the microcomputer system equipped with Survey Software, and containing calibrating procedure and process of measurement in Survey Software, calibrating procedure and process of measurement respectively contain a contact deflection error correction computing formula.

The method that after applying above-mentioned tensile sample fracture, contracting position, footpath minimum diameter measurement apparatus measures, installs including measurement apparatus, demarcates and measure, and operating procedure is as follows:

1) measurement apparatus is installed: by measurement cross section or the normal diameter section of standard cylinder of the rectilinear edge registration coupon measuring clamping cutting edge and locating dowel of sensor, the both sides force carriage of the cylindrical hole on frame bottom support, the V-shaped groove of the support two-arm column part respectively with both sides, sample measurement cross section is made to contact, simultaneously sensor under the elastic pressure effect of compression spring against sample, measure clamping cutting edge vertical clamping sample, the rectilinear edge of locating dowel and sample perpendicular contact, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Produce certain deflection deformation；

2) measurement apparatus is demarcated: the full-bridge circuit of sensor accesses the strain signal collection-modulate circuit of data collecting instrument, on each standard cylinder measurement apparatus being successively arranged on by standard diameter value order from small to large, write down each reading ε of data collecting instrument_r1, ε_r2..., ε_rn, then draw data collecting instrument reading ε by linear fit method_rWith the functional relation of diameter value d, i.e. fit equation

ε_r=Ad+B (a)

In formula (a), A and B is constant, presses formula (b) respectively and (c) calculates:

$A=\frac{\underset{i=1}{\overset{n}{\&Sigma;}}(d_i-\stackrel{\&OverBar;}{d_i})({\mathrm{\&epsiv;}}_{ri}^{*}-\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}})}{\underset{i=1}{\overset{n}{\&Sigma;}}{(d_i-\stackrel{\&OverBar;}{d_i})}^2}---\left(b\right)$

$B=\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}}-A\&times;\stackrel{\&OverBar;}{d_i}---\left(c\right)$

${\mathrm{\&epsiv;}}_{ri}^{*}=\frac{\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}}{\frac{3{\mathrm{h\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-e)}{3{\mathrm{\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0+{\mathrm{\&delta;}}_i-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0+{\mathrm{\&delta;}}_i-m)}^3}}{\mathrm{\&epsiv;}}_{ri}---\left(d\right)$

${\mathrm{\&delta;}}_i=\frac{d_i-d_0}{2}---\left(e\right)$

In formula (b) and (c), n represents the number of standard cylinder, d_iRepresent the diameter value of different-diameter standard cylinder,It is the diameter value d of each standard cylinder_iArithmetical average,Represent that with diameter value be d_iData collecting instrument reading ε corresponding to standard cylinder_riCorrection value,It is each reading ε of data collecting instrument_riCorrection valueArithmetical average；In formula (d), h represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The thickness of cervical region ce section, α represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The ratio of the thickness h of the thickness H of head ac section and cervical region ce section, L₀Represent datum diameter rule and measure the contact point of clamping cutting edge to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, e represents strain ga(u)ge R₁、R₂、R₃And R₄Central point to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, m represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The length of cervical region ce section, δ_iExpression diameter value is d_iStandard cylinder with measure clamping cutting edge contact point relative to L₀The displacement produced, i.e. contact deflection amount；

3) diameter measurement: measurement apparatus is arranged on fracture (19) and passes through on the tension failure sample (18) engaged, accesses data collecting instrument, the reading strain ε of record data collecting instrument by the full-bridge circuit of sensor (1)_r, by formula (f), (g) and the diameter d of (h) calculating sample:

$d=d_0+\frac{1}{2}(s-\frac{1}{\mathrm{\&Omega;}}-d_0)-\frac{1}{2}\sqrt{{(s-\frac{1}{\mathrm{\&Omega;}}-d_0)}^2+\frac{4}{\mathrm{\&Omega;}}(\frac{{\mathrm{\&epsiv;}}_r-B}{A}-d_0)}---\left(f\right)$

$\mathrm{\&Omega;}=\frac{3{\mathrm{h\&alpha;}}^3-\mathrm{\&eta;}(3{\mathrm{\&alpha;}}^3{m}^2+6{\mathrm{\&alpha;}}^3(L_0-m)m+3{\left(L_0-m\right)}^2)}{6{\mathrm{h\&alpha;}}^3(L_0-e)}---\left(g\right)$

$\mathrm{\&eta;}=\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}---\left(h\right).$

In the present invention, described tension failure sample includes tension failure sample, the variable cross-section pure bending fatigue sample that material mechanical performance tests, and non-uniform shaft that bus is curve and Step Shaft axial workpiece.

The feature of the present invention:

1, composition sensor is coordinated with U-shaped elastomer, so that the measurement clamping blade of sensor can be accurately positioned in tested sample by the locating dowel with rectilinear edge.

2, in standard cylinder is set as that datum diameter is advised；The contact point of blade is clamped as the datum mark demarcated and measure using datum diameter rule and sensor measurement.

3, under conditions of utilizing locating dowel that sensor is positioned and utilizing datum diameter rule to determine datum mark, by coefficient A and B in formula (b), (d), (c) and (e) digital simulation equation (a), thus eliminate because of the contact deflection error of each standard cylinder diameter difference generation in the demarcations link of the system of measurement.

4, use formula (f), (g) and (h) to calculate the diameter of sample, thus eliminate the contact deflection error produced because of specimen finish difference in measurement links.

5, the band guide rail detent mechanism being made up of with sensor band V-shaped groove support and flexible member, ensure that sensor measurement clamping blade place plane is mutually perpendicular to the axis of sample, and the installation of measurement apparatus had both been suitable for manual operations, it is suitable for again mechanically actuated mode automatically or semi-automatically.

Accompanying drawing explanation

Fig. 1 is the three-view diagram that measurement apparatus is arranged on sample, wherein: (a) front view, (b) left view, (c) top view；

Fig. 2 is the three-view diagram of U-shaped elastomer, wherein: (a) front view, (b) left view, (c) top view；

Fig. 3 is the three-view diagram of support, wherein: (a) front view, (b) top view, (c) top view；

Fig. 4 is the three-view diagram of sword block, wherein: (a) front view, (b) top view, (c) top view；

Fig. 5 is two views of locating dowel, wherein: (a) front view, and (b) top view；

Fig. 6 is the structure chart of guide rod；

Fig. 7 is the schematic diagram of full-bridge circuit；

Fig. 8 is the organigram of measurement apparatus of the present invention, wherein: (a) front view, (b) right view, (c) top view；

In figure: 1. sensor, 2. support, 3. compression spring, 4.U shape elastomer, 5. sword block, 6. locating dowel, 7. guide rod, the cylindrical hole in 8.U shape elastic body base B axes O, 9. rectangular through-hole, the 10. rectilinear edge of sword block, the rectilinear edge of 11. locating dowels, 12. female threads, 13. screw threads, 14. cylindrical flat caps, 15. rectangular channels, the cylindrical hole on 16. supports, 17.V shape groove, 18. samples, 19. fractures, R₁、R₂、R₃And R₄. it is respectively single shaft strain ga(u)ge, B. pedestal, B₁. left Cantilever Beams of Variable Cross Section, B₂. right Cantilever Beams of Variable Cross Section, C₁. triangular head, C₂. rectangle root, E₁. lower surface, E₂. step surface, E₃. upper surface, E₄. lower surface.

Detailed description of the invention

Below in conjunction with accompanying drawing, the invention will be further described.

With reference to Fig. 1 Fig. 8, after the tensile sample fracture of the present invention, contracting position, footpath minimum diameter measurement apparatus includes sensor 1, support 2, compression spring 3, standard and data collecting instrument；

Sensor 1 has 4, two sword blocks of a U-shaped elastomer, 6, guide rod 7 of 5, locating dowel and four pieces of single shaft strain ga(u)ge R₁、R₂、R₃And R₄；U-shaped elastomer 4 symmetrical shape, its structure includes pedestal B and is fixed on the left Cantilever Beams of Variable Cross Section B at pedestal B two ends₁With right Cantilever Beams of Variable Cross Section B₂, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Cross section be rectangle, and it is divided into head ac and cervical region ce two sections from free end a to root e, the cross-sectional area of head ac section is more than the cross-sectional area of cervical region ce section, and the axes O of U-shaped elastomer 4 pedestal B is machined with a cylindrical hole 8, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Respectively being machined with a rectangular through-hole 9 at free end a, the two rectangular through-hole 9 is in coaxial position；The structure of each sword block 5 is divided into triangular head C₁With rectangle root C₂Two sections, triangular head C₁The rectilinear edge that front end is sword block 5 10；The top of locating dowel 6 is triangle, and the top of triangle is the rectilinear edge 11 of the locating dowel being perpendicular to mast axis, and the bottom of locating dowel 6 is by lower surface E₁Rise and be machined with female thread 12 along mast axis；The structure of guide rod 7 is divided into upper, middle and lower segment, epimere to be threaded 13, and stage casing is uiform section circular shaft, and hypomere is cylindrical flat cap 14, and the diameter in stage casing is more than the diameter of epimere, and stage casing forms the step surface E being perpendicular to guide rod axis at the section being connected with epimere₂；Two sword blocks 5 are by its rectangle root C₂With left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The interference fit of rectangular through-hole 9, be inlaid in left Cantilever Beams of Variable Cross Section B respectively₁With right Cantilever Beams of Variable Cross Section B₂On, and it is in the inner side of U-shaped elastomer 4；The rectilinear edge 10 of two sword blocks 5 is parallel to each other, and constitutes the measurement clamping cutting edge of sensor 1；Single shaft strain ga(u)ge R₁And R₂It is respectively adhered on left Cantilever Beams of Variable Cross Section B₁Inside and outside cervical region ce, its grid axle and left Cantilever Beams of Variable Cross Section B₁Axis parallel；Single shaft strain ga(u)ge R₃And R₄It is respectively adhered on right Cantilever Beams of Variable Cross Section B₂Inside and outside cervical region ce, its grid axle and right Cantilever Beams of Variable Cross Section B₂Axis parallel；Four pieces of strain ga(u)ge R₁、R₂、R₃And R₄Full-bridge circuit is connected into by wire；

Support 2 is U-shaped structure, symmetrical shape；Centre bottom support 2, axes O along support 2 is coaxially machined with the cylindrical hole 16 on a rectangular channel 15 and a support, rectangular channel 15 is positioned at the inner side of support U-shaped structure, and it is through along the direction vertical with the middle face of support 2, in the upper end of support 2 two-arm, be respectively machined with a V-shaped groove 17, the two V-shaped groove 17 shape with towards identical, and it being in coaxial position, its axis is positioned at the middle face of support 2；

Guide rod 7 is through the cylindrical hole 8 in cylindrical hole 16, compression spring 3 and the U-shaped elastomer 4 pedestal B axes O on support 2 bottom bracket, and U-shaped elastomer 4 is coaxial with support 2, and the middle face of U-shaped elastomer 4 is mutually perpendicular to the middle face of support 2；Guide rod 7 epimere screw thread 13 screws with the female thread 12 of locating dowel 6 bottom being positioned at inside U-shaped elastomer 4, locating dowel 6 lower surface E₁Upper surface E with U-shaped elastic body base B₃Compression fit, the step surface E in guide rod 7 stage casing₂Lower surface E with U-shaped elastomer 4 pedestal B₄Compression fit；Compression spring 3 is positioned at the stage casing of guide rod 7, its two ends contact with U-shaped elastomer 4 and support 2 respectively, the cylindrical flat cap 14 of guide rod 7 hypomere props up support 2 bottom lower surface, being slidably matched and being slidably matched of rectangular channel 15 of pedestal B two sides and frame bottom of U-shaped elastomer 4 of guide rod 7 stage casing and the cylindrical hole 16 on support 2 bottom bracket, collectively form a pair along sensor 1 and the guiding rail mechanism in support 2 common axis O direction, sensor 1 is made to have the one-movement-freedom-degree along the two common axis O direction relative to support 2, simultaneously, there is certain fit clearance in this guide rail mechanism, sensor 1 is made to have the small degree of freedom (being typically advisable) rotated around the two common axis O with ± 0.5 ° relative to support 2；The rectilinear edge 11 of locating dowel 6 is positioned at below sword block 5, and coplanar, vertical with the rectilinear edge 10 of two sword blocks 5；

Standard is made up of standard cylinder and datum diameter rule of some different-diameters, the diameter value d of datum diameter rule₀It is defined as datum diameter；Quantity n >=4 of standard cylinder；The diameter d of standard cylinder₁、d₂..., d_nBy order arrangement from small to large, minimum diameter value d therein₁Primary leading s more than 1 two sword blocks 5 of sensor；The diameter value d of datum diameter rule₀Meet relation d₁<d₀<d_n；

Data collecting instrument includes strain signal collection-modulate circuit and the microcomputer system equipped with Survey Software, and containing calibrating procedure and process of measurement in Survey Software, calibrating procedure and process of measurement respectively contain a contact deflection error correction computing formula.

The measuring method of contracting position, footpath minimum diameter measurement apparatus after rupturing with tensile sample, installs including measurement apparatus, demarcates and measure, and operating procedure is as follows:

1) measurement apparatus is installed: by measurement cross section or the normal diameter section of standard cylinder of rectilinear edge 11 registration coupon 18 measuring clamping cutting edge and locating dowel 6 of sensor 1, force carriage 2 from bottom to top, both sides of the cylindrical hole 16 on support 2 bottom bracket, the column part making the V-shaped groove 17 of support 2 two-arm measure both sides, cross section with sample 18 respectively contacts, simultaneously sensor 1 under the elastic pressure effect of compression spring 3 against sample 18, measure clamping cutting edge by sample 18 vertical clamping, rectilinear edge 11 and sample 18 perpendicular contact of locating dowel 6, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Produce certain deflection deformation；

2) measurement apparatus is demarcated: the full-bridge circuit of sensor 1 accesses the strain signal collection-modulate circuit of data collecting instrument, on each standard cylinder measurement apparatus being successively arranged on by standard diameter value order from small to large, write down each reading ε of data collecting instrument_r1, ε_r2..., ε_rn, then draw data collecting instrument reading ε by linear fit method_rWith the functional relation of diameter value d, i.e. fit equation

ε_r=Ad+B (a)

In formula (a), A and B is constant, presses formula (b) respectively and (c) calculates:

$A=\frac{\underset{i=1}{\overset{n}{\&Sigma;}}(d_i-\stackrel{\&OverBar;}{d_i})({\mathrm{\&epsiv;}}_{ri}^{*}-\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}})}{\underset{i=1}{\overset{n}{\&Sigma;}}{(d_i-\stackrel{\&OverBar;}{d_i})}^2}---\left(b\right)$

$B=\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}}-A\&times;\stackrel{\&OverBar;}{d_i}---\left(c\right)$

${\mathrm{\&epsiv;}}_{ri}^{*}=\frac{\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}}{\frac{3{\mathrm{h\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-e)}{3{\mathrm{\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0+{\mathrm{\&delta;}}_i-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0+{\mathrm{\&delta;}}_i-m)}^3}}{\mathrm{\&epsiv;}}_{ri}---\left(d\right)$

${\mathrm{\&delta;}}_i=\frac{d_i-d_0}{2}---\left(e\right)$

In formula (b) and (c), n represents the number of standard cylinder, d_iRepresent the diameter value of different-diameter standard cylinder,It is the diameter value d of each standard cylinder_iArithmetical average,Represent that with diameter value be d_iData collecting instrument reading ε corresponding to standard cylinder_riCorrection value,It is each reading ε of data collecting instrument_riCorrection valueArithmetical average；In formula (d), h represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The thickness of cervical region ce section, α represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The ratio of the thickness h of the thickness H of head ac section and cervical region ce section, L₀Represent datum diameter rule and measure the contact point of clamping cutting edge to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, e represents strain ga(u)ge R₁、R₂、R₃And R₄Central point to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, m represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The length of cervical region ce section, δ_iExpression diameter value is d_iStandard cylinder with measure clamping cutting edge contact point relative to L₀The displacement produced, i.e. contact deflection amount；

3) diameter measurement: engaged at fracture 19 by tension failure sample 18, is arranged on measurement apparatus on tension failure sample 18, measures the cross section needing to measure in rectilinear edge 11 registration coupon of cutting edge and locating dowel 6；The full-bridge circuit of sensor 1 is accessed data collecting instrument, the reading strain ε of record data collecting instrument_r, by formula (f), (g) and the diameter d of (h) calculating sample:

$d=d_0+\frac{1}{2}(s-\frac{1}{\mathrm{\&Omega;}}-d_0)-\frac{1}{2}\sqrt{{(s-\frac{1}{\mathrm{\&Omega;}}-d_0)}^2+\frac{4}{\mathrm{\&Omega;}}(\frac{{\mathrm{\&epsiv;}}_r-B}{A}-d_0)}---\left(f\right)$

$\mathrm{\&Omega;}=\frac{3{\mathrm{h\&alpha;}}^3-\mathrm{\&eta;}(3{\mathrm{\&alpha;}}^3{m}^2+6{\mathrm{\&alpha;}}^3(L_0-m)m+3{\left(L_0-m\right)}^2)}{6{\mathrm{h\&alpha;}}^3(L_0-e)}---\left(g\right)$

$\mathrm{\&eta;}=\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}---\left(h\right).$

Contact deflection error correction Computing Principle:

1. the correction algorithm in calibrating procedure

Theoretical theoretical with strain electrical measurement according to beam deflection, when measurement apparatus being arranged on the standard cylinder or sample 18 that diameter value is d, the reading strain ε of data collecting instrument_rCan represent by below equation

${\mathrm{\&epsiv;}}_r=\frac{3{\mathrm{h\&alpha;}}^3(L-e)}{3{\mathrm{\&alpha;}}^3(L-m)m^2+3{\mathrm{\&alpha;}}^3{(L-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L-m)}^3}(d-s)---\left(1\right)$

In formula (1), L represents sample 18 and the contact point measuring clamping cutting edge to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, referred to as contact height；H represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The thickness of cervical region ce section, α represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The ratio of the thickness h of the thickness H of head ac section and cervical region ce section, e represents strain ga(u)ge R₁、R₂、R₃And R₄Central point to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, m represents left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The length of cervical region ce section, s represents the primary leading measuring clamping cutting edge.

Arbitrarily select one to be only used as datum diameter rule in standard cylinder, it is stipulated that diameter on the basis of its normal diameter value, use d₀Represent.Use L₀Represent the contact height that datum diameter rule are corresponding, useRepresent the reading strain that datum diameter rule are corresponding, thenWith L₀Relation can be write as

${\mathrm{\&epsiv;}}_r^{*}=\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}(d-s)---\left(2\right)$

Contact height L in formula (1) can be write as

L=L₀+ΔL (3)

Form, the Δ L on formula (3) the right represents that the contact height L corresponding to standard cylinder or sample that diameter value is d is relative to L₀The displacement produced, referred to as contact deflection.Standard cylinder or sample that diameter value is different have different contact deflection amounts, if demarcating and do not considering in Measurement Algorithm the existence of contact deflection Δ L, i.e. contact height L are regarded as constant, the reading strain ε directly obtained by formula (1)_rCarry out demarcating and survey calculation, then can produce certain measurement error, referred to as contact deflection error.Use locating dowel 6 and set datum diameter rule and datum diameter d₀Under conditions of, the constant that the contact deflection amount corresponding to each standard cylinder all determines that, and can be collectively expressed as

${\mathrm{\&Delta;L}}_i=\frac{d_i-d_0}{2},(i=1,2,...,n)---\left(4\right)$

In formula (4), d_iIt is the diameter value of the standard cylinder of serial number i, Δ L_iIt it is the contact deflection amount corresponding to standard cylinder of serial number i.By formula (1)～(4), can solve

${\mathrm{\&epsiv;}}_{ri}^{*}=\frac{\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}}{\frac{3{\mathrm{h\&alpha;}}^3(L_0+{\mathrm{\&Delta;L}}_i-e)}{3{\mathrm{\&alpha;}}^3(L_0+{\mathrm{\&Delta;L}}_i-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0+{\mathrm{\&Delta;L}}_i-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0+{\mathrm{\&Delta;L}}_i-m)}^3}}{\mathrm{\&epsiv;}}_{ri}---\left(5\right)$

Formula (5) left sideIt is containing contact deflection reading strain ε_riCorrected Calculation result, referred to as equivalent strain reading.Timing signal, usesSet up the fitting formula of calculated diameter value d, i.e. formula (a), contact deflection error can be eliminated.

2. the correction algorithm in process of measurement

During measurement, it is continuing with datum diameter d₀.With this understanding, theoretical according to beam deflection and strain electrical measurement is theoretical, can derive below equation:

$\mathrm{\&Delta;}d=\frac{1}{2}(s-\frac{1}{\mathrm{\&Omega;}}-d_0)-\frac{1}{2}\sqrt{{(s-\frac{1}{\mathrm{\&Omega;}}-d_0)}^2+\frac{4}{\mathrm{\&Omega;}}{\mathrm{\&delta;d}}^{*}}---\left(6\right)$

$\mathrm{\&Omega;}=\frac{3{\mathrm{h\&alpha;}}^3-\mathrm{\&eta;}(3{\mathrm{\&alpha;}}^3{m}^2+6{\mathrm{\&alpha;}}^3(L_0-m)m+3{\left(L_0-m\right)}^2)}{6{\mathrm{h\&alpha;}}^3(L_0-e)}---(6-a)$

δd^*=d^*-d₀ (6-b)

$\mathrm{\&eta;}=\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}---(6-c)$

In formula (6), Δ d is that the diameter d of tested sample is relative to datum diameter d₀Knots modification；d^*It is by reading strain ε_rIt is directly substituted into formula (a) and obtains diameter value, i.e.

$d^{*}=\frac{{\mathrm{\&epsiv;}}_r-A}{B}---\left(7\right)$

Because there is contact deflection when measuring, so d^*Comprise contact deflection error.d^*It is properly termed as apparent diameter.The δ d obtained by formula (6-a)^*, it is apparent diameter δ d^*Relative to datum diameter d₀Knots modification.Formula (6) is by δ d^*Make corrected Calculation, eliminate contact deflection error, obtain Δ d.Obtain rear Δ d, i.e. can get the diameter d of tested sample:

D=d₀+Δd (8) 。

Claims (3)

1. contracting position, footpath minimum diameter measurement apparatus after tensile sample fracture, is characterized in that including sensor (1), support (2), compression spring (3), standard and data collecting instrument；

Sensor (1) have a U-shaped elastomer (4), two sword blocks (5), locating dowel (6), one Guide rod (7) and four pieces of single shaft strain ga(u)ge R₁、R₂、R₃And R₄；U-shaped elastomer (4) symmetrical shape, Its structure includes pedestal B and is fixed on the left Cantilever Beams of Variable Cross Section B at pedestal B two ends₁Hang with right variable cross-section Arm beam B₂, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Cross section be rectangle, and from from Being divided into head ac and cervical region ce two sections by end a to root e, the cross-sectional area of head ac section is more than neck The cross-sectional area of portion's ce section, the axes O of U-shaped elastomer (4) pedestal B is machined with a cylinder and leads to Hole (8), left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂One respectively it is machined with at free end a Individual rectangular through-hole (9), the two rectangular through-hole (9) is in coaxial position；The structure of each sword block (5) is divided into Triangular head C₁With rectangle root C₂Two sections, triangular head C₁The straight line cutter that front end is sword block (5) Sword (10)；The top of locating dowel (6) is triangle, and the top of triangle is the locating dowel being perpendicular to mast axis Rectilinear edge (11), the bottom of locating dowel (6) is by lower surface E₁Rise and be machined with female thread (12) along mast axis； The structure of guide rod (7) is divided into upper, middle and lower segment, epimere to be threaded (13), and stage casing is uiform section circle Axle, hypomere is cylindrical flat cap (14), and the diameter in stage casing is being held in the mouth with epimere more than the diameter of epimere, stage casing The section connect forms the step surface E being perpendicular to guide rod axis₂；Two sword blocks (5) are by its rectangle root C₂With left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂The interference fit of rectangular through-hole (9), point It is not inlaid in left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂On, and it is in U-shaped elastomer (4) Inner side；The rectilinear edge (10) of two sword blocks (5) is parallel to each other, and constitutes the measurement clamping sword of sensor (1) Mouthful；Single shaft strain ga(u)ge R₁And R₂It is respectively adhered on left Cantilever Beams of Variable Cross Section B₁Cervical region ce's is inside and outside Both sides, its grid axle and left Cantilever Beams of Variable Cross Section B₁Axis parallel；Single shaft strain ga(u)ge R₃And R₄It is respectively adhered on Right Cantilever Beams of Variable Cross Section B₂Inside and outside cervical region ce, its grid axle and right Cantilever Beams of Variable Cross Section B₂Axis Parallel；Four pieces of strain ga(u)ge R₁、R₂、R₃And R₄Full-bridge circuit is connected into by wire；

Support (2) is U-shaped structure, symmetrical shape；In the centre of support (2) bottom, along support (2) Axes O is coaxially machined with the cylindrical hole (16) on a rectangular channel (15) and a support, rectangular channel (15) inner side of support U-shaped structure it is positioned at, and through along the direction vertical with the middle face of support (2), The upper end of support (2) two-arm, is respectively machined with a V-shaped groove (17), the two V-shaped groove (17) shape and court To identical, and being in coaxial position, its axis is positioned at the middle face of support (2)；

Guide rod (7) is through cylindrical hole (16), compression spring (3) and the U-shaped bullet on support (2) bottom bracket Cylindrical hole (8) in gonosome (4) pedestal B axes O, U-shaped elastomer (4) is coaxial with support (2), U The middle face of shape elastomer (4) is mutually perpendicular to the middle face of support (2)；Guide rod (7) epimere screw thread (13) be positioned at U The female thread (12) of locating dowel (6) bottom of shape elastomer (4) inner side screws, locating dowel (6) lower surface E₁With U The upper surface E of shape elastic body base B₃Compression fit, the step surface E in guide rod (7) stage casing₂Elastic with U-shaped The lower surface E of body (4) pedestal B₄Compression fit；Compression spring (3) is positioned at the stage casing of guide rod (7), its two ends Contacting with U-shaped elastomer (4) and support (2) respectively, the cylindrical flat cap (14) of guide rod (7) hypomere props up support (2) Bottom lower surface, guide rod (7) stage casing is slidably matched with cylindrical hole (16) on support (2) bottom bracket And being slidably matched, altogether of rectangular channel (15) of the pedestal B two sides of U-shaped elastomer (4) and frame bottom With composition one pair along sensor (1) and the guiding rail mechanism in support (2) common axis O direction, make sensing Device (1) has the one-movement-freedom-degree along the two common axis O direction relative to support (2), and meanwhile, this leads There is certain fit clearance in rail mechanism, makes sensor (1) have around the two common axis relative to support (2) The small degree of freedom that O rotates；The rectilinear edge (11) of locating dowel (6) is positioned at sword block (5) lower section, and with two The rectilinear edge (10) of individual sword block (5) is coplanar, vertical；

Standard is made up of standard cylinder and datum diameter rule of some different-diameters, datum diameter The diameter value d of rule₀It is defined as datum diameter；Quantity n >=4 of standard cylinder；The diameter of standard cylinder d₁、d₂..., d_nBy order arrangement from small to large, minimum diameter value d therein₁More than sensor (1) The primary leading s of two sword blocks (5)；The diameter value d of datum diameter rule₀Meet relation d₁<d₀<d_n；

Data collecting instrument includes strain signal collection-modulate circuit and the pico computer system equipped with Survey Software System, containing calibrating procedure and process of measurement in Survey Software, calibrating procedure and process of measurement respectively contain one Contact deflection error correction computing formula.

2. contracting position, footpath minimum diameter measurement apparatus after application tensile sample fracture described in claim 1 Measuring method, is characterized in that including that measurement apparatus is installed, demarcated and measure, and operating procedure is as follows:

1) measurement apparatus is installed: the measurement of sensor (1) is clamped cutting edge and the rectilinear edge of locating dowel (6) (11) registration coupon (18) measure cross section or the normal diameter section of standard cylinder, in support (2) bottom The both sides force carriage (2) of the cylindrical hole (16) on frame, makes the V-shaped groove (17) of support (2) two-arm respectively The column part measuring both sides, cross section with sample (18) contacts, the sensor (1) bullet in compression spring (3) simultaneously Property pressure effect under against sample (18), measure clamping cutting edge vertical clamping sample (18), locating dowel (6) Rectilinear edge (11) and sample (18) perpendicular contact, left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂ Produce certain deflection deformation；

2) measurement apparatus is demarcated: the full-bridge circuit of sensor (1) accesses the strain signal of data collecting instrument Collection-modulate circuit, by measurement apparatus by standard diameter value order from small to large be successively arranged on each On standard cylinder, write down each reading ε of data collecting instrument_r1, ε_r2..., ε_rn, then use Linear Quasi Conjunction method draws data collecting instrument reading ε_rWith the functional relation of diameter value d, i.e. fit equation

ε_r=Ad+B (a)

In formula (a), A and B is constant, presses formula (b) respectively and (c) calculates:

$A=\frac{\underset{i=1}{\overset{n}{\&Sigma;}}(d_i-\stackrel{\&OverBar;}{d_i})({\mathrm{\&epsiv;}}_{ri}^{*}-\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}})}{\underset{i=1}{\overset{n}{\&Sigma;}}{(d_i-\stackrel{\&OverBar;}{d_i})}^2}---\left(b\right)$

$B=\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{ri}^{*}}-A\&times;\stackrel{\&OverBar;}{d_i}---\left(c\right)$

${\mathrm{\&epsiv;}}_{ri}^{*}=\frac{\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}}{\frac{3{\mathrm{h\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-e)}{3{\mathrm{\&alpha;}}^3(L_0+{\mathrm{\&delta;}}_i-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0+{\mathrm{\&delta;}}_i-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0+{\mathrm{\&delta;}}_i-m)}^3}}{\mathrm{\&epsiv;}}_{ri}---\left(d\right)$

${\mathrm{\&delta;}}_i=\frac{d_i-d_0}{2}---\left(e\right)$

In formula (b) and (c), n represents the number of standard cylinder, d_iRepresent different-diameter standard cylinder Diameter value,It is the diameter value d of each standard cylinder_iArithmetical average,Represent and diameter value For d_iData collecting instrument reading ε corresponding to standard cylinder_riCorrection value,It is data collecting instrument each time Reading ε_riCorrection valueArithmetical average；In formula (d), h represents left Cantilever Beams of Variable Cross Section B₁With Right Cantilever Beams of Variable Cross Section B₂The thickness of cervical region ce section, α represents left Cantilever Beams of Variable Cross Section B₁With right variable cross-section Cantilever beam B₂The ratio of the thickness h of the thickness H of head ac section and cervical region ce section, L₀Represent that benchmark is straight Footpath rule with measure the contact point of clamping cutting edge to left Cantilever Beams of Variable Cross Section B₁With right Cantilever Beams of Variable Cross Section B₂Root The distance of cross section, portion e, e represents strain ga(u)ge R₁、R₂、R₃And R₄Central point cut to left change Face cantilever beam B₁With right Cantilever Beams of Variable Cross Section B₂The distance of root section e, m represents left variable cross-section cantilever Beam B₁With right Cantilever Beams of Variable Cross Section B₂The length of cervical region ce section, δ_iExpression diameter value is d_iStandard cylinder Body and measurement clamp the contact point of cutting edge relative to L₀The displacement produced, i.e. contact deflection amount；

3) diameter measurement: measurement apparatus is arranged on fracture (19) through the tension failure sample (18) engaged On, the full-bridge circuit of sensor (1) is accessed data collecting instrument, the reading strain ε of record data collecting instrument_r, By formula (f), (g) and the diameter d of (h) calculating sample:

$d=d_0+\frac{1}{2}(s-\frac{1}{\mathrm{\&Omega;}}-d_0)-\frac{1}{2}\sqrt{{(s-\frac{1}{\mathrm{\&Omega;}}-d_0)}^2+\frac{4}{\mathrm{\&Omega;}}(\frac{{\mathrm{\&epsiv;}}_r-B}{A}-d_0)}---\left(f\right)$

$\mathrm{\&Omega;}=\frac{3{\mathrm{h\&alpha;}}^3-\mathrm{\&eta;}(3{\mathrm{\&alpha;}}^3{m}^2+6{\mathrm{\&alpha;}}^3(L_0-m)m+3{(L_0-m)}^2)}{6{\mathrm{h\&alpha;}}^3(L_0-e)}---\left(g\right)$

$\mathrm{\&eta;}=\frac{3{\mathrm{h\&alpha;}}^3(L_0-e)}{3{\mathrm{\&alpha;}}^3(L_0-m)m^2+3{\mathrm{\&alpha;}}^3{(L_0-m)}^{2}m+{\mathrm{\&alpha;}}^3{m}^3+{(L_0-m)}^3}---\left(h\right).$

Contracting position, footpath minimum diameter measurement apparatus after tensile sample the most according to claim 2 fracture Measuring method, it is characterized in that described tension failure sample (18) includes what material mechanical performance was tested Tension failure sample, variable cross-section pure bending fatigue sample, and non-uniform shaft that bus is curve and step Axle axial workpiece.