CN102506808A - Method for dynamically measuring deformation amount of mechanical structure - Google Patents

Abstract

The invention relates to the field of measurement of a geometrical quantity and particularly discloses a method for dynamically measuring a deformation amount of a mechanical structure. A glass ceramics ball is used as a measured target and is arranged on a measured workpiece by utilizing a design method and coordinate values before and after the environment temperature is changed are measured to obtain the positional deviation of each characteristic point after the temperature is changed. Due to the adoption of the indirect measuring method, the problem of measuring the deformation of a composite structure is solved. Meanwhile, the standard ball is made of a glass ceramics material and the coefficient of thermal expansion of the material is low and is close to that of a composite, so that an error of introducing the standard ball is minimized. A shaded part of the workpiece is measured by utilizing a reflection method. A complex structure is measured by using a non-contact mode.

Description

A kind of dynamic measurement method of physical construction deflection

Technical field

The present invention relates to the geometric sense metering field, particularly a kind of method of under high and low temperature environment, malformation being carried out kinetic measurement.

Background technology

Because the singularity of aerospace engineering working environment is had higher requirement to material.Have bigger temperature variation in the space environment, the temperature difference can reach 200 ℃, and this will make the bigger thermal deformations of space vehicle structure generation such as satellite influences mechanical property and electrical property; The aircraft California bearing ratio is an important indicator weighing its performance, if the satellite weight that is transmitted in the space reduces 1kg, the rocket that then delivers it can reduce 1t.In conjunction with the practical application of aerospace engineering, need material to have characteristics such as thermal expansivity is little, lightweight, specific strength is high, specific modulus is big, compound substance meets the requirements just, also is widely used in space industry.

Aircraft needs to comprise thermocycling, vibration test, impulse test etc. through multiple its structural stability of environmental test checking before emission.In order to verify its stability, need the measuring mechanism deflection, whether meet design requirement through calculating checking.And the processing characteristics of compound substance can not show a candle to metal material; Its surface precision is relatively poor relatively; Even uncertainty of measurement can appear greater than accuracy requirement, directly measurement can not be satisfied technical requirement, so how to avoid the influence of material to become the key that solves problems of measurement.

The problems of measurement that solves the composite structure distortion is significant; Can measure the distortion of each parts of aircraft before and after the environmental test; Parts such as high-precision optical system, accurate machine construction particularly, certifying organization's stability is for the reliability of aerospacecraft provides metering to ensure.

Summary of the invention

The object of the present invention is to provide a kind of dynamic measurement method of the physical construction deflection of under high and low temperature environment, realizing.

Technical scheme of the present invention is following:

A kind of dynamic measurement method of physical construction deflection, this method comprises following steps:

1) select for use the devitrified glass ball as measured target, the centre of sphere is as unique point;

2) above-mentioned devitrified glass ball is fixed on the measured workpiece;

3) with the devitrified glass ball as the reference coordinate point, measure the sphere centre coordinate value of devitrified glass ball, the coordinate of each centre of sphere is designated as x _i, y _i, z _iI=1,2,3 ... N, N are the unique point number;

4) plane mirror is fixed, following condition is satisfied in the position of plane mirror: confirm a devitrified glass ball on the measured workpiece, its picture at plane mirror can be measured to;

5) unique point through the plane mirror measuring workpieces back side;

6) change temperature conditions, the change in location of N unique point of record; And write down under each time point, the characteristic point position coordinate is X _Ij, Y _Ij, Z _Ij, j=1,2,3...M, M are the time point number;

7) draw the position deviation of each unique point after the temperature change through following formula

$\mathrm{\Δ}=\sqrt{{(X_{\mathrm{ij}}-x_i)}^2+{(Y_{\mathrm{ij}}-y_i)}^2+{(Z_{\mathrm{ij}}-z_i)}^2}.$

In the dynamic measurement method of above-mentioned a kind of physical construction deflection, described step 2) carry out as follows;

A) make connection semisphere frock, radius is R, frock center processing counterbore;

B) the position processing through hole that needs monitoring of structures to change on the measured workpiece surface;

C) use the bolt and nut of invar manufacturing that the semisphere frock is fixed on the measured workpiece, and on screw thread, be coated with high temperature resistant silica gel;

D) in frock hemisphere groove, be coated with high temperature resistant silica gel, the devitrified glass ball is fixed in the hemisphere groove;

E) fixedly finish and placed 24 hours;

F) each devitrified glass ball is numbered.

Remarkable result of the present invention is:

(1) changes traditional direct measuring method, use indirect measurement method, solved the problems of measurement of composite structure distortion;

(2) use microcrystal glass material production standard ball, material thermal expansion coefficient is little, and near compound substance, the error that standard ball is introduced is reduced to minimum;

(3) use the centre of sphere as unique point, accurate positioning, measuring accuracy is high;

(4) utilize the reflection method for measuring workpiece part that is blocked, use the noncontact mode that labyrinth is measured;

Description of drawings

Fig. 1 is a malformation measuring method process flow diagram of the present invention;

Fig. 2 is the reflectometry principle schematic.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment the present invention is done further explain.

As shown in Figure 1, introduce this method by concrete steps.

(1) select for use the devitrified glass ball as measured target, the centre of sphere is as unique point;

The present invention uses the devitrified glass ball as measured target, and the centre of sphere is as unique point, and the radius of a ball is R, and R is value according to actual needs, R=20～30mm in the present embodiment, and sphericity is 0.1～0.2 micron.

In the present embodiment, select the material of devitrified glass for use as metal ball.Because the singularity of aerospace engineering, the common thermal expansivity of institute's compound substance of selecting for use is lower, and this just need select the close material of performance for use.The present invention need select high reflecting material for use because measuring principle limits, and the invar material does not have these characteristics, thus select for use devitrified glass as the measured target material, and the ball surface needs plated film.

(2) fixed characteristic points

Before carrying out environmental test, the devitrified glass ball is fixed on measured workpiece, the surface of the physical construction of promptly being surveyed, by fixing like following step:

A) make connection semisphere frock, radius is R, frock center processing counterbore;

B) the position processing through hole that needs monitoring of structures to change on the measured workpiece surface;

C) use the bolt and nut of invar manufacturing that the semisphere frock is fixed on the measured workpiece, and on screw thread, be coated with high temperature resistant silica gel;

D) in frock hemisphere groove, be coated with high temperature resistant silica gel, the devitrified glass ball is fixed in the hemisphere groove;

E) fixedly finish and placed 24 hours;

F) each devitrified glass ball is numbered;

(3) original state is measured

In high-low temperature chamber, use laser radar scanner to measure all devitrified glass ball sphere centre coordinate values the measured workpiece fixed placement that fixes the devitrified glass ball, as the reference coordinate point, the coordinate of each centre of sphere is designated as (x according to number record each point coordinate position _i, y _i, z _i) (i=1,2,3 ... N, N are the unique point number).

Measurement this moment state should satisfy: a) laser radar is measured through the windowpane of high-low temperature chamber, and placement location need guarantee to measure all unique points; B) installed surface is installed, and prevents distortion; C) installation process can not be collided glass bead; D) handling process is avoided vibrating by a relatively large margin, avoids suddenly cold and hot.

(4) reflection method for measuring back of work unique point

A) at first need confirm the position of catoptron.As shown in Figure 3, before the measured workpiece that the devitrified glass ball has been installed is placed on plane mirror, confirm a devitrified glass ball, its picture at plane mirror also can be measured by laser radar scanner, can confirm the plane mirror position through 2,

B) confirm reflector position after, through the unique point at the plane mirror measuring workpieces back side.

(5) the thermocycling process is measured

The temperature variation of control incubator uses laser radar scanner according to the automatic measurement of (3) step institute's reference coordinate point of surveying each point position.Because the laser radar scanner measuring speed is very fast, single target ball Measuring Time is no more than 1 second, and the temperature variant deflection of compound substance slowly carries out, so the influence that Measuring Time is brought can be ignored.Along with the change of environment, the each point change in location under the record condition of different temperatures.

(6) data processing

Because this measuring method is not real-time measurement, but because measuring speed much larger than malformation speed, uses the method for interpolation to calculate the coordinate position of each time point, the position coordinates of each time point is (X _Ij, Y _Ij, Z _Ij) (i=1,2,3 ... N, N are the unique point number, j=1, and 2,3...M, M are the time point number).Calculate each point deviation under the different temperatures environment through

, analysis temperature is to the influence of malformation.

Claims (2)

1. the dynamic measurement method of a physical construction deflection is characterized in that, this method comprises following steps:

1) select for use the devitrified glass ball as measured target, the centre of sphere is as unique point;

2) above-mentioned devitrified glass ball is fixed on the measured workpiece;

3) with the devitrified glass ball as the reference coordinate point, measure the sphere centre coordinate value of devitrified glass ball, the coordinate of each centre of sphere is designated as x _i, y _i, z _iI=1,2,3 ... N, N are the unique point number;

4) plane mirror is fixed, following condition is satisfied in the position of plane mirror: confirm a devitrified glass ball on the measured workpiece, its picture at plane mirror can be measured to;

5) unique point through the plane mirror measuring workpieces back side;

6) change temperature conditions, the change in location of N unique point of record; And write down under each time point, the characteristic point position coordinate is X _Ij, Y _Ij, Z _Ij, j=1,2,3..M, M are the time point number;

7) draw the position deviation of each unique point after the temperature change through following formula

$\mathrm{\Δ}=\sqrt{{(X_{\mathrm{ij}}-x_i)}^2+{(Y_{\mathrm{ij}}-y_i)}^2+{(Z_{\mathrm{ij}}-z_i)}^2}.$

2. the dynamic measurement method of a kind of physical construction deflection as claimed in claim 1 is characterized in that, described step 2) carry out as follows;

A) make connection semisphere frock, radius is R, frock center processing counterbore;

B) the position processing through hole that needs monitoring of structures to change on the measured workpiece surface;

C) use the bolt and nut of invar manufacturing that the semisphere frock is fixed on the measured workpiece, and on screw thread, be coated with high temperature resistant silica gel;

D) in frock hemisphere groove, be coated with high temperature resistant silica gel, the devitrified glass ball is fixed in the hemisphere groove;

E) fixedly finish and placed 24 hours;

F) each devitrified glass ball is numbered.

Images