CN1235023C - Photoelctric combined force-measuring method - Google Patents

Abstract

The present invention relates to an opto-electronic combined force-measuring method, which comprises the following steps: key parts of a mechanical device to be measured are taken and are processed into photoelastic models, similar force which is exerted on the mechanical device is exerted to the photoelastic models to obtain a shape factor: phi= [E/2 (1+mu)]*[K<L>K<T>P<M>/Nsigma<o>]; small sheets with the same materials as the key parts are produced, and electric resistance strain gauges are stuck on the small sheets to form measuring bridges; the calibrated small sheets are stuck on measuring points of the key machinery parts by glue; a strain value epsilon is measured through the electric resistance strain gauges; the measurement of the mechanical force is completed through multiplying the shape factor phi by the strain value epsilon, namely P=phi * epsilon. The method has the advantages that when the actual measurement of super magnitude load is carried out, no expensive pressure sensor needs processing, and thereby, the trouble of the calibration is eliminated. When the opto-electronic combined method is used, the working load can be directly obtained as long as epsilon can be measured on an on-site stressed member. The measuring method has the advantages of quickness, accuracy, time saving and money economization.

Description

The compound force measuring method of a kind of photoelectricity

Technical field

The present invention relates to the compound force measuring method of a kind of photoelectricity, belong to the dynamometry technical field.

Background technology

For some main equipments or some high precision equipment, in default load display instrument or instrument while on these equipment and when these equipment do not allow to install ready-made sensor or device, it is very difficult reaching measurement target when wanting to understand the used load on these equipment.Some traditional heavy (merchant) mills for example, the roll-force tonnage all about kiloton, is rolled the power test to this milling train and will processes a large-scale pressure head, because size is very big, except processing and fabricating takes costliness, be problematic in that the demarcation to this pressure head is difficult to find the large-tonnage testing machine.Another typical problem is as the steel plate shearing machine on the 2030 cold continuous rolling lines, for the motor of selecting to be complementary, when design, need understand shearing force, and this shearer structure is not only compact, and is slider-crank mechanism, can not lay on equipment and put any type of sensor.

Summary of the invention

The objective of the invention is on equipment the dynamometry problem of placing any type of sensor can not be installed in order to solve in the engineering survey, the present invention proposes compound force measuring method of a kind of photoelectricity and system.

Technical scheme of the present invention is achieved like this, and its method step is:

1, getting vital part on the plant equipment that need are surveyed is object, is processed into photoelastic model,

Model is applied the similar power that acts on the plant equipment, obtains the shape coefficient of the part at similar measuring point place: $\mathrm{\&Phi;}=\frac{E}{2(1+\mathrm{\&mu;})}\frac{K_L{K}_T{P}^M}{{\mathrm{N\&sigma;}}_o}$

The elastic modulus of E-part; The Poisson ratio of μ-part

K _LThe shape ratio of-part and photoelastic model; K _TThe thickness ratio of-part and photoelastic model; P ^M-similar power; The fringe order of N-photoelastic model; σ _o-stress fringe value;

2, make a flakelet, its material is pasted selected resistance strain gage with the material of plant equipment vital part on flakelet, form measuring bridge, connects the input/output signal line;

3, flakelet is demarcated, obtained calibration coefficient Use glue (or epoxy resin) flakelet to be pasted the measuring point place of crucial mechanical component then;

4, by the resistance strain gage on the flakelet on the crucial mechanical component, the strain value ε when recording equipment work;

5, being multiplied each other in multiplier by shape coefficient Φ and strain value ε is P=Φ * ε, finishes mechanical force measurement.

Its principle of work is: form measuring bridge by the resistance strain gage on flakelet, establish each brachium pontis and satisfy R ₁=R ₂=R ₃=R ₄, then the reading strain has: ε=2 (ε ₁+ ε ₂); Be in some stress states as measuring point, introducing generalized Hooke's law has: $\mathrm{\&epsiv;}=\frac{2(1+\mathrm{\&mu;})}{E}({\mathrm{\&sigma;}}_1+{\mathrm{\&sigma;}}_2);$ Application photoelasticity theory, the mathematic(al) representation of its deviator stress line is: ${\mathrm{\&sigma;}}_1^M-{\mathrm{\&sigma;}}_2^M={\mathrm{N\&sigma;}}_o;$ Have according to similarity theory: $K_{\mathrm{\&sigma;}}=\frac{K_P}{K_L{K}_T},$ So have: ${\mathrm{\&sigma;}}_1-{\mathrm{\&sigma;}}_2=\frac{K_P}{K_L{K}_T}N{\mathrm{\&sigma;}}_o$ With $\mathrm{\&epsiv;}=\frac{2(1+\mathrm{\&mu;})}{E}\frac{K_P}{K_L{K}_T}{\mathrm{N\&sigma;}}_o,$ So $P=\frac{E}{2(1+\mathrm{\&mu;})}\frac{K_L{K}_T{P}^M}{{\mathrm{N\&sigma;}}_o}\mathrm{\&epsiv;},$ P=Φ * ε then, the part shape coefficient is: $\mathrm{\&Phi;}=\frac{E}{2(1+\mathrm{\&mu;})}\frac{K_L{K}_L{P}^M}{{\mathrm{N\&sigma;}}_o}.$

This method is a kind of extremely useful force measuring method, promptly to the load actual measurement of some excess levels, need not remove to process the pressure transducer of a costliness, thereby more need not the tired brain of demarcation.The photoelectricity composite algorithm has been arranged,, just can directly obtain operating load as long as can measure ε on the primary structure member at the scene.Both rapidly accurately, it was economical to save time again in this measurement.

Description of drawings

The full-bridge strain paster synoptic diagram of Fig. 1 for pasting on the flakelet;

Fig. 2 is the luxuriant instrumentation logic design frame chart of making according to this method.

Embodiment

Connect with 2030 Baosteel Cold Rolling, 2030 hot rollings acid and to wash that 2030 new pickling planisher groups are example on the production line.After new pickling planisher group is installed, find to have casting flaw on the planisher frame through nondestructive examination.Because the existence of defective makes that the real work load (being roll-force) of 2030 new pickling planishers is more much smaller than rated load like this, has influenced production output and progress.For to 2030 exerting oneself property of planisher frame evaluations, at first to know the real work roll-force of this planisher.Owing on frame, traditional sensor can't be installed, for this reason, adopt the compound force measuring method of this method-photoelectricity.In 1: 25 ratio processing photoelasticity frame model, by photoelastic analysis, find out the position of best flakelet, promptly find the part stress stress gradient to change little position, as framework pillar; Make a flakelet, its material is identical with framework pillar, is 40G, its size is long * wide * thick be 25 * 1.2 * 100 (mm), determine Φ=12.636 * 10 ⁹On flakelet, paste selected resistance strain gage, form measuring bridge, flakelet is demarcated, obtain calibration coefficient Use 502 glue (or epoxy resin) flakelet to be pasted the measuring point place of framework pillar then; Strain value ε when recording equipment work; As shown in Figure 2, the ε input signal through amplification, A/D conversion, multiplier, relatively amplify, enter behind the amplification driver computer multiplier and obtain roll-force P with multiplying each other by above-mentioned determined Φ _Survey=2500KN, the actual roll-force P that records through the scene _Real=2520KN.Both have only 0.8% at error.And should actual roll-force only account for 25% of specified roll-force, so if there is not degree of impairment in 2030 planisher frames, then the rolling potentiality of frame are very big.Then pass through fracture mechanics analysis and FEM (finite element) calculation etc. again, conclusion is the intensity that the defective of this frame does not influence frame, and the roll-force of this milling train can be brought up to specified roll-force, thereby improves output, obtains the approval and the favorable comment of manufacturer for this reason.

Claims (1)

1, the compound force measuring method of a kind of photoelectricity is characterised in that, the steps include:

1) getting vital part on the plant equipment that need are surveyed is object, is processed into photoelastic model,

Model is applied the similar power that acts on the plant equipment, obtains the shape coefficient of the part at similar measuring point place: $\mathrm{\&Phi;}=\frac{E}{2\left(16\mathrm{\&mu;}\right)}\frac{K_L{K}_T{P}^M}{N{\mathrm{\&sigma;}}_0}$

The elastic modulus of E-part; The Poisson ratio of μ-part

K _LThe shape ratio of-part and photoelastic model; K _T-part and photoelastic model

The thickness ratio; P ^M-similar power; The fringe order of N-photoelastic model;

σ _o-stress fringe value;

2) make a flakelet, its material is with the material of plant equipment vital part, and adhering resistance strain sheets on flakelet is formed measuring bridge, connects the input/output signal line;

3) flakelet is demarcated, obtained calibration coefficient

Then with glue or

Epoxy resin pastes flakelet at the measuring point place of crucial mechanical component;

4) by the resistance strain gage on the flakelet on the crucial mechanical component, the strain value ε when recording equipment work;

5) being multiplied each other in multiplier by shape coefficient Φ and strain value ε is P=Φ * ε, finishes mechanical force measurement.

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