CN1546979A - Method and device for measuring fiber compression bending properties - Google Patents

Abstract

The invention is a method and device for measuring fiber compression flexural performance, refers to the measurement for cotton, fur, silk, hemp and chemical fiber, and other high performance fiber or fiber type material. The invention includes a force-shift measuring mechanism made up of high precision micro force sensor, multifunctional upper grip holder and the subjacent holder which can move in parallel and vertically, it can acquire the head end stress of fiber and fiber axial deformation data and simulate the puncture effect of human skin. The invention uses optical system to realize the synchronization, changes the deformation under pressure of fiber axial into digital image to be processed, acquires the fiber fineness, holding length, flexibility and curvature of each point and shift, and controls the measured parameter through the computer real-time collected data, measures the real-time pressure, flexibility, fiber bending shape and so on deformation curve and relative character parameter through theory model and algorithm software. It especially applies to axial compressing and bending performance measurement of convex fiber with diameter of 5-200mum and length of 1-25mm, and the stretching measurement of fiber with length of 0-150mm.

Description

Method and device for measuring fiber compression bending properties

technical field

The invention relates to a measurement method applied to textile comfort performance, fiber characteristics and production quality control, especially suitable for measuring compression, bending and tensile properties of cotton, wool, silk, hemp, chemical fiber and other high-performance fibers or fibrous substances Methods and devices.

Background technique

The tactile comfort of textiles is an important factor for wearing comfort, especially for wool or linen fabrics. Consumers often feel itchy or prickly when wearing them, causing physical and psychological discomfort, and changing their purchase and use attitudes.

Due to the complexity of the human body's nerve perception, there are currently three main methods commonly used by enterprises and testing institutions for subjective evaluation. ①Animal electrode stimulation experiment: it uses electrodes or metal needles to stimulate the animal experiment. This method is based on the fact that the neurosensory body of the animal is very similar to the neurosensory body of the human body, which is the premise of the experimental evaluation. However, the human experiment has not been calibrated, that is, the difference has not been identified, and the correlation between human electrical stimulation and fabric pricking is still a purely theoretical study, and there is no practical result. ②Forearm test: Select different fabric samples, sew them into sleeves and put them on the forearm of the testee. The tester wears rubber gloves and gently pats or moves back and forth on the fabric. Evaluation of itching sensation and degree. The experimental data proves that the forearm test is in good agreement with the itchy feeling of the fabric when worn, but the test results are to a certain extent affected by more external conditions and the subjective influence of the testee. ③Try-on evaluation: try on the clothes within the specified time limit, and then give evaluation grades respectively. This method is theoretically feasible, but the actual operation is very difficult, the sample required for the test is large, the test cost is high, and the test cycle is long.

Effective attempts have been made to objective testing methods abroad. ①Film method: Under a certain pressure, the fibers on the surface of the fabric can leave indentations on the PTFE film. The researchers believe that the depth of these indentations is related to the force required for the fibers to produce indentations. Scratch to evaluate the degree of itching of the fabric. Theoretically, the objective evaluation can be solved by image processing and analysis, but there is no practical report. ②Measuring the protruding fiber with a laser counter: WRONZ [New Zealand Wool Research Organization] uses a laser counter developed by itself to test the hairiness protruding from the fabric. This method only considers the root number of fibers, and ignores the thickness of fibers, so the order of tingling often conflicts. ③ Improved audio device: This improved audio device is similar to a record player. The fabric cut into a circle is placed on a disc to rotate at a constant speed. The relative linear velocity between the probe and the cloth surface is 12cm/s. When the probe Feel the bending force of the fiber when you pluck it. The height of the probe can be adjusted according to the fabric. The pulse signal obtained by the probe is amplified by the amplifier and recorded by the counter. This method considers the situation too simply, because the hairs on the surface of the fabric are not all separated, some hairs are entangled, and some hairs are ring-shaped fibers. If the probe passes through the middle of such hairs, it will cause misjudgment. ④ Toggle method: The University of Shga Prefecture in Japan uses a one-way point-toggle fiber bending method to measure the flexural stiffness of the fiber, because the offset of the toggle loading point makes the measurement data value discrete too large. Moreover, the applied load is a lateral force, so this method can only express the bending of the fiber, but cannot characterize the piercing of the fiber.

The single fiber axial compression performance is the most direct and basic factor reflecting the itching caused by the hairiness on the surface of the fabric. When the fabric is in contact with the skin, under a small pressure, the contact between the human skin and the fabric is mainly due to the hairiness with a certain stiffness and hardness; When the pressure is high, the hairiness will fall, and the warp and weft floating points of the fabric structure will form the supporting surface. For the former, the hairiness of the fabric is the main support, resulting in four contact patterns. Therefore, simulating the pricking and scratching process and its force value is the key to directly predict and effectively evaluate the prickling sensation produced by the contact between fibers and human skin.

Contents of the invention

In view of the existing comfort evaluation of textiles, there are deficiencies in both subjective evaluation methods and objective testing methods. To this end, the present invention provides a method and system device for measuring fiber compression and bending performance, which can simulate the process of different fabric surface hairiness piercing and translational scraping, as well as the change of force value in the process of contact with the skin. The invention solves the measurement of tiny force and realizes the accuracy and synchronous observation of fiber morphology, and at the same time solves the problems of small fiber and effective fiber needle preparation as well as its combined technology and computer sampling, calculation and analysis software.

According to the conclusion of the above-mentioned analysis of "simulating the pricking process, directly predicting the force value generated by the fiber in contact with the human skin is the key to effective evaluation". Accordingly, the device of the present invention is mainly used to measure the compression, bending and combination properties of fibers under the action of axial force.

The principle and method of fiber axial compression force, deflection form combination and dynamic measurement are as follows:

(1) During the fiber axial compression and bending process, not only the compression force value and axial displacement are measured, but also the deflection measurement and the curvature and lateral displacement measurement of each point are completed through the image analysis of the fiber shape change.

(2) Through the analysis of the continuous change of the compression force and deflection of the fiber in the process of axial compression and bending, the indicators reflecting the compression and bending performance of the fiber, such as the compression modulus, bending stiffness, and bending yield point, are calculated.

(3) Adjust the time and mode of action on the compression and bending of textile fibers, and complete the static and dynamic piercing measurement of fibers and the combined measurement of tension, compression and bending.

(4) Use the horizontal movement of the fiber under constant pressure or constant compression displacement to complete the measurement of fiber scraping and rubbing.

The basic concept of a method and device for fiber compression bending performance measurement of the present invention:

(1) In order to facilitate sample loading and measurement, a window-opening paper sample preparation template is used. According to the length of the required fiber needle, paste it on the crosspiece of the template with double-sided tape, and then paste the fiber on the double-sided tape in a parallel and straight way, and cut along the dotted line in the direction parallel to the double-sided tape, so that the lengths are equal A group of fiber needles; or cut at a certain angle with the double-sided adhesive to obtain a group of fiber needles with a gradient change in length; it can also be cut twice to obtain a group of fiber needles with a stepwise change in length; or along with the fiber Cut along the dotted line parallel to the axis to obtain a single-fiber needle.

(2) The micro-force measurement is completed through the micro-force measurement mechanism composed of a high-precision micro-force sensor, a cantilever beam, a multi-functional upper chuck and a lower gripper. The multifunctional upper chuck can be replaced. The lower holder can move and rotate horizontally and vertically to obtain data such as fiber axial compression force and displacement.

(3) Through the shape measurement mechanism composed of light source, condenser lens, diaphragm, objective lens, CCD camera and point light source, the centering, focusing and measurement of illumination and imaging fibers are completed, and the static image of fiber bending under axial pressure of single fiber is obtained Image and fiber translation deformation dynamic image, as well as manual measurement and automatic calculation of fiber fineness, grip length, deflection and curvature of each point and other changing parameters.

(4) In the signal processing system, the force measurement system consists of force sensors and displacement sensors (ie, angular displacement or time recorders) output signals and their corresponding acquisition, amplification, analog-to-digital conversion, preprocessing, storage, output components and function blocks Composition; through the imaging system composed of the image acquisition card and the basic image processing unit, the data transmission of the pressure-displacement curve and the deflection-displacement curve is completed and connected to the computer.

(5) Through the computer processing system composed of data acquisition and calculation module, parameter setting and control module and control and transmission module, the control and adjustment of the measurement action process and the processing, display and display of pressure-displacement curve and deflection-displacement curve are completed. Preservation, image observation processing and image preservation, measurement and analysis of points, lines and distances.

The main components of a method and device for measuring fiber compression bending performance of the present invention:

One is sample preparation: in order to facilitate sample loading and measurement, a window-type paper sample preparation template is used. According to the length of the required fiber needle, use double-sided tape to paste it on the crosspiece of the template, and then paste the fiber parallel to the double-sided tape, cut along the dotted line in the direction parallel to the double-sided tape, and get the same length A group of fiber needles; or cut at a certain angle with the double-sided adhesive to obtain a group of fiber needles with a gradient change in length; it can also be cut twice to obtain a group of fiber needles with a stepwise change in length; or along with the fiber Cut the dotted line parallel to the axis to obtain a single-fiber needle. This method can also be used to compare the compression of fibers of different fineness under the condition of certain length.

The second is the design of the fiber holding end: the lower end of the single fiber is held vertically by insertion, and its small screw is used for fixing; the surface film of the upper chuck can be replaced with different materials to simulate the micropore effect on the skin surface. polymer or sandpaper.

The third is the precision sample table lifting system: through the setting program and driving circuit of the computer, the micro-motor and the transmission mechanism are controlled to ensure the precise vertical and horizontal movement of the sample table and the change of the moving speed, so as to effectively control the amount of fiber deformation and Fiber loading and unloading speed.

The fourth is optical imaging and image acquisition and measurement system: including light source, condenser lens, diaphragm, objective lens, CCD camera, auxiliary point light source and computer with image processing software. Directly convert the amplified analog image of the fiber head end into a digital image through a digital camera to minimize the distortion of the image signal; use IEEE1394 interface for digital CCD signal and computer data transmission digital image; through the computer The obtained image is processed, and the shape measurement and calculation of the fiber head end are carried out.

The fifth is the force measurement system: the slowly changing electrical signal of the force sensor due to the force is very weak (including the static force) and the electrical signal generated by the slowly changing force must be amplified by temperature compensation and filter amplifier circuit Only by using A/D conversion can the analog voltage signal be converted into a digital voltage signal. In the conversion process of analog quantity and digital signal, the digital signal needs to be read into the computer software. Before that, it is first necessary to set the relationship between the input voltage range and the digital output, and then specify the input port and give the command to start the A/D conversion. , after confirming the signal conversion, read the numbers into computer memory.

Sixth, critical strength calculation: According to the Euler compression bar model, when the load P approaches a certain critical value, the deflection increases infinitely. Therefore, when the axial force is applied to the fiber, if the length of the fiber is larger than the diameter, it is very easy to lose stability, and the fiber will only be bent instead of directly compressed. Often the fibers are axially compressed in form, necessarily causing itchy irritation. Its retained compressed form is related to the length, thickness and stiffness of the lancet. The vast majority of fiber punctures are bent.

The working principle of the device in the above method: first, the computer sets the parameters, performs zero adjustment and compensation control, and the lower gripper is driven by a micro-motor to start an upward movement, and the micro-force change is output by the analog voltage value through the sensor, which is converted into a digital voltage by A/D The signal is input to the computer; at the same time, the CCD microscopic camera converts the deformation of the single fiber under force into a digital image and inputs it to the computer for data processing and calculation. Through the above process, variables such as fiber deflection, length, and fineness, as well as pressure-displacement curves and deflection-displacement curves are obtained. The computer controls the driving circuit to make the micro-motor drive the precise vertical and horizontal movement of the sample platform lifting system, and adjust the moving speed to effectively control the amount of fiber deformation and the speed of fiber loading and unloading.

A kind of method and device for fiber compression bending performance measurement of the present invention, the parameter calculation of its built theoretical model is as follows:

One end of the fiber is fixed on the lower chuck (or upper chuck), and the other end is in a free straight state. With the continuous upward movement of the lower chuck, the fiber contacts the upper (or lower) chuck and is compressed. Because the protruding length of the fiber to be tested is short, or the fiber itself is relatively rigid (such as ramie fiber), the fiber needle under compression can be considered as a compression rod model with one end fixed and the other end free, and the corresponding critical load is

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; cr</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{\mathrm{<span\; class="notranslate">\; EI</span>}}{{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 20.19</span>}\mathrm{<span\; class="notranslate">\; EI</span>}}{{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The minimum moment of inertia of a perfect circle is I=πr ⁴ /4. Since the cross-section of the hemp fiber is not a perfect circle, it always bends to the direction where it is most likely to bend when the fiber is bent. Therefore, when calculating the critical load of the fiber, Need to introduce section shape factor η _f , so

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; cr</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 20.19</span>}{\mathrm{<span\; class="notranslate">\; E\&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 20.19</span>}{\mathrm{<span\; class="notranslate">\; \&pi;r</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; E\&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 5.05</span>}{\mathrm{<span\; class="notranslate">\; E\&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&pi;L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 5.05</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; E\&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&pi;\&rho;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: E-the modulus of elasticity of the compression rod; I-the minimum moment of inertia of the cross-section of the compression rod; M-the bending moment; L-the length of the compression rod; S-the cross-sectional area of the compression rod; N _t -the linear density of the fiber _; Section shape factor in the formula

In (2), let $K=\frac{5.05\&times;{10}^{-5}{\mathrm{E\&eta;}}_f}{\mathrm{\&pi;\&rho;}},$ but $P_{\mathrm{cr}}=K\frac{N_t^2}{L^2}\&CenterDot;$ Fitting straight line slope K as shown in accompanying drawing 9, can obtain fiber flexural modulus

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;K\&rho;</span>}}{\mathrm{<span\; class="notranslate">\; 5.05</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

When the fiber needles are compressed, the fiber needles, under the action of axial pressure, are initially in pure compression because no unbalanced bending of the fibers occurs. Therefore, the compressive modulus _Ec can be obtained from the slope of the rising part (section ab) of the compression bending curve in accompanying drawing 7, namely

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; dP</span>}}{\mathrm{<span\; class="notranslate">\; dZ</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; dP</span>}}{\mathrm{<span\; class="notranslate">\; dZ</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the formula, dP/dZ-derivative of compressive force value relative to displacement, (dP/dZ)max is maximum slope value; L ₀ -protruding length of fiber needle; N _t -linear density of fiber needle; A-fiber needle The highest point of the cross-sectional area curve is the critical pressure point, that is, the point of the maximum piercing force, and its value is the critical pressure P _max . When the pressure exceeds this critical pressure, the strut buckles and fails.

Experiment 1: As shown in accompanying drawing 8, the slope value of the straight line is obtained by the linear fitting equation, K=0.0209; the cross-sectional shape coefficient value of the fiber is obtained by analyzing the cross-sectional shape of the hemp fiber, η _f ≈0.8; the density value of the fiber ρ =1.85, which is substituted into formula (3), and the average flexural E modulus of ramie fiber is calculated to be 2469.1cN/cm ² .

Experiment 2: a, b, c, and d in the accompanying drawing 9 are hemp fibers whose average fineness (public branch) is 1432, 1618, 1866, and 2072, respectively, and whose critical pressure P _max values are 0.0823, 0.0774, and 0.0731 respectively , 0.0728mN; the average compressive modulus E _c is: 2209.3cN/cm ² . At the same time, its compression curve verified the proportional relationship between the axial compression strength of the fiber needle and the fiber fineness.

The present invention is achieved through the following technical solutions:

① Obtain the fiber sample through the sample preparation template - fiber needle;

②In order to reduce the influence of air flow and vibration on the measurement, the entire measurement process of fiber axial compression performance is completed in a measurement cavity, and the steps are:

a. Select the upper chuck for multi-functional compression and its membrane surface simulation material and adjust the clamping method; the lower clamper completes the gripping of the fiber needle.

b. Roughly estimate the center position of the X-axis of the fiber needle through the observation of the magnifying glass on the openable panel at the front of the measuring cavity.

c. Through computer processing and control of the micro-motor, the lower holder on the sample platform is driven by the transmission mechanism to move up and down in the vertical direction to complete the axial bending of the fiber needle; through the left and right movement of the lower holder in the horizontal direction , to complete the sliding friction in the bent state of the fiber needle.

d. Move the lower gripper horizontally along the X-axis direction and manually fine-tune the Y-axis guide rail on the lower gripper through the rotating disc on the lower gripper manually and the X-axis guide rail on the lower gripper by manual fine-tuning Move the lower holder horizontally along the Y-axis direction, so that the axis of the fiber needle is centered and perpendicular to the optical path with the bending plane; at the same time, the light from the light source passes through the condenser lens, aperture, fiber needle, objective lens or directly to the CCD camera on the same axis Complete the centering of the optical path and the sample fiber needle; convert the formed fiber needle compression bending simulation image into a digital image through analog-to-digital conversion, and measure and calculate bending deformation and deflection through computer processing.

e. Through the force sensor, the analog signal of the dynamic measurement of the small force value change at the free contact end of the fiber needle is input to the computer for data processing through temperature compensation, filtering, amplification circuit and analog-to-digital conversion.

f. Computer processing performs data processing based on the given theoretical model and algorithm, and draws the pressure-displacement curve and deflection-displacement curve of the fiber needle compression deformation; combines the image processing in the fiber needle compression process and the numerical solution of the above-mentioned curves to solve the fiber needle Fineness, grip length, deflection, compression, flexural modulus, critical compression force value and stress distribution.

Here's how to make fiber tensile measurements:

In order to reduce the influence of air vibration on the measurement, the entire measurement process of fiber tensile measurement is completed in a measurement cavity, and the steps are:

a. Set the height position of the micro force sensor, replace the upper clamp for stretching, adjust the clamping method, and complete the vertical holding of the fiber needle by the lower clamp, and perform the stretching measurement of the fiber needle.

The remaining parts b to f are the same as the measurement steps of fiber compression bending performance.

Description of drawings

Fig. 1 is a schematic diagram of the structural principle of a fiber compression, bending and stretching device of the present invention.

Fig. 2 Block diagram of the transmission system of the lifting and translation control of the sample platform.

Figure 3 is a schematic diagram of the point light source intersecting the X and Y axes.

Figure 4 Schematic diagram of sample preparation template and sample preparation.

Figure 5 block diagram of data acquisition and control system.

Figure 6 measurement control flow chart.

Fig. 7 Theoretical graph of fiber axial compression.

Fig. 8 The relationship between the maximum compression force P and N _t ² /L ² .

Fig. 9 Compression curves of fibers of different lengths and finenesses.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

The present invention is a kind of method that is used for fiber compression bending property measurement:

① Obtain a fiber sample through the sample preparation template 43 - fiber needle 41;

②In order to reduce the influence of air flow and vibration on the measurement, the entire measurement process of fiber axial compression performance is completed in a measurement chamber 1, and the steps are:

a. Select the upper clamp 32 for multi-functional compression and its membrane surface simulation material 33 and adjust the clamping method; the lower clamp 5 completes the vertical holding of the fiber needle 41 .

b. Roughly estimate the center position of the X-axis of the fiber needle 41 through the observation of the magnifying glass 13 mounted on the openable transparent panel at the front of the measurement cavity 1 .

c. Through computer processing 9, the micromotor 61 is controlled by the transmission mechanism to drive the lower holder 5 on the sample platform 6 to move up and down in the vertical direction to complete the axial bending of the fiber needle 41; through the lower holder 5, the horizontal The left and right movement of the direction completes the sliding friction of the fiber needle 41 in a bent state.

d. Make the lower clamper 5 move horizontally along the X-axis direction and manually fine-tune the lower clamper 5 through the rotating disc 54 on the manual lower clamper 5 and the X-axis guide rail 52 on the manual fine-tuning lower clamper 5 The upper Y-axis guide rail 53 moves the lower holder 5 horizontally along the Y-axis direction, so that the axis of the fiber needle 41 is centered and perpendicular to the optical path with the bending plane; at the same time, the light is passed from the light source 71 through the condenser lens 72, the diaphragm 73, the fiber The needle 41, the objective lens 74 or directly to the CCD camera 75 complete the centering of the optical path and the sample fiber needle 41 on the same axis; through the analog-to-digital conversion 82, the compressed and curved analog image of the formed fiber needle 41 is converted into a digital image, Measure and calculate bending deformation and deflection through computer processing.

e. Through the force sensor 21, the analog signal for dynamic measurement of the tiny force value change at the free contact end of the fiber needle 41 is input to the computer processing 9 for data processing through the temperature compensation, filtering and amplification circuit 81 and the analog-to-digital conversion 82.

f, computer processing 9 carries out data processing according to given theoretical model and algorithm, draws the pressure-displacement curve and deflection-displacement curve of fiber needle 41 compression deformation; Combining image processing and above-mentioned curve numerical solution in the process of fiber needle 41 compression Fiber needle 41 fineness, grip length, deflection, compression, flexural modulus, critical compression force value and stress distribution.

In order to reduce the influence of air flow and vibration on the measurement, the entire measurement process of fiber tensile measurement performance is completed in a measurement chamber 1, and the steps are:

Set the height position of the force sensor 21, replace the upper chuck 22 for multi-functional stretching, adjust the clamping method, and the lower clamper 5 completes the vertical holding of the fiber needle 41, and performs the stretching measurement of the fiber needle 41. Its follow-up operation is the same as that of the compression bending performance measurement method.

A device for fiber compression bending performance measurement:

An observable magnifying glass 13 is inlaid on the openable transparent panel on the front of the measurement chamber 1 to reduce the influence of air flow and vibration on the measurement; the measurement chamber 1 is mainly composed of: force measurement mechanism 2, multi-functional upper clamp The head 3, the lower holder 5, the optical imaging system 7, the analog signal processing 8, the computer processing 9 and a sample platform 6 driven by a micro-motor 61 transmission mechanism controlled by a computer.

a. The force measuring mechanism 2 is composed of a force sensor 21 , a multifunctional upper chuck 3 movably connected with it, and a rotatable and movable lower holder 5 located on the sample platform 6 .

b. The optical imaging system 7 is composed of a light source 71, a condenser lens 72, a diaphragm 73, an objective lens 74, a CCD camera 75, and a point light source 76 arranged at an angle with the X and Y axes.

c. Analog signal processing 8 The analog signals output by the force sensor 21 and the displacement sensor 20 of the force measuring system are collected, temperature compensated, filtered, amplified 81, analog-to-digital converted 82, pre-processing, storage, output components and functional modules 83 compositions.

d. The computer processing 9 is composed of a data acquisition and calculation module (91), a parameter setting and control module (92) and a control and transmission module (93).

A device for measuring fiber compression performance, the inner wall of the measuring cavity 1 is coated with a color complementary to the fiber needle 41 to be tested; the force sensor 21 is a high-precision micro force sensor with a cantilever beam structure; the multifunctional upper chuck 3 It includes replaceable upper chuck 31 for stretching, upper chuck 32 for compression and its chuck membrane 33; the lower gripper 5 is composed of lower chuck 51 and its linked manual fine-tuning mechanism X-axis guide rail 52 and Y-axis Composed of guide rail 53 and rotating disk 54; the function of displacement sensor 20 is realized through the cooperation of micro-motor 61 rotation speed and computer clock controller; the angle between point light source 76 and X, Y axis is 30-60 °.

A device for measuring fiber compressibility, the inner wall of the measuring chamber 1 is coated with a black color complementary to the fiber needle 41 to be tested; the angle between the point light source 76 and the X and Y axes is 45°.

A device for measuring fiber compression performance, the chuck film 33 is made of high polymer and sandpaper.

The main performance index of device of the present invention:

Measuring range 0～10gf measurement accuracy ±0.005mN Linearity (standard deviation) ±0.005mN Applicable temperature range 0～40℃ Lower gripper movement measurement error (X, Z axis) ±0.005mm (vibration without influence measurement) Moving speed of lower platform (X, Z axis) 1～600mm/min(adjustable) The movement range and precision of the Y-axis fine-tuning of the lower chuck 0～10mm; ±0.01mm The lower chuck rotates 360° Stepless The maximum stroke of the lower gripper 100mm Double-position setting of the upper chuck   Up and down distance 90mm Optical system magnification (high power observation) 200 times, depth of field 5mm Low magnification field of view diameter φ ≥20mm, precision 5μm Image display resolution 0.5μm (2 thousand points per millimeter) Single fiber diameter 5～200μm Single fiber protruding length 1～25mm

The method and device for measuring fiber compression, bending and tensile properties of the present invention are applicable to the measurement of cotton, wool, silk, hemp, chemical fiber and other high-performance fibers or fibrous substances. It can be applied to the evaluation of textile comfort performance, the measurement of fiber compression, bending and tensile characteristics, and the quality control in production.

The theoretical model and algorithm software can quickly provide real-time compressive stress-strain curve; deflection-strain curve; fiber bending shape and related characteristic parameters. The system has strong functions and can measure fiber tensile, compressive, bending properties and morphological deformation characteristics; it has a wide range of applications and can be used for fiber mechanical performance measurement, fabric hairiness and fabric tactile comfort evaluation, and fiber processing quality control, etc.; high measurement accuracy, results Accurate and reliable. Since the system adopts computer-controlled transmission, image and data acquisition, and has built models and software, the present invention not only has the advantages of simple operation, high degree of automation, friendly interface and one machine, one measurement of multiple indicators, but also has the advantages of numerical The characteristics of high degree and fast data processing. It can quickly measure the axial compression and bending properties of fibers with a diameter of 5-200 μm and a protruding length of 1-25 mm. And after changing the clamping form and position of the upper chuck, the short-distance (0-25mm) clamping tensile measurement and the long-distance (0-150mm) clamping tensile measurement can be completed.

Claims (7)

1, a kind of method of fiber bending compression performance measurement is characterized in that:

1. obtain fiber samples-fiber needle (41) by sample preparation template (43);

2. measure lining, chamber (1) at one and finish following operation:

A, choose compression with upper grip (32), chuck film (33) surface simulation material with adjust method of clamping; Lower gripper (5) is finished fiber needle (41) and is gripped;

B, by measuring the observation of the magnifier (13) that studs with on the positive openable panel in chamber (1), the center of guestimate fiber needle (41) X-axis;

C, by Computer Processing (9) control micromotor (61), drive the lower gripper (5) that is positioned on the sample platform (6) through gear train, vertically do to rise, descending motion, finish fiber needle (41) axial bending; Move by the left and right of lower gripper (5) horizontal direction, finish the sliding friction under fiber needle (41) case of bending;

D, by hand rotation and the fine setting translation lower gripper (5), make fiber needle (41) axis centering and with plane of bending perpendicular to light path; Simultaneously, make light by light source (71), fiber needle (41), object lens (74) or directly to CCD camera (75) on same axis, finish the centering of light path and sample fiber pin (41); Convert fiber needle (41) the bending compression simulated image that is become to digital image by analog to digital conversion (82), machine is handled (9) and is measured, calculates flexural deformation and amount of deflection as calculated;

E, by force transducer (21), the simulating signal that little power value of the free contact jaw of kinetic measurement fiber needle (41) changes is through collection and temperature compensation, filtering and amplifying circuit (81) and analog to digital conversion (82), input Computer Processing (9) is for data processing;

F, Computer Processing (9) are carried out data processing according to given theoretical model and algorithm, draw the pressure-displacement curve and the amount of deflection-displacement curve of fiber needle (41) compression deformation; Image processing and above-mentioned curve numerical value solve fiber needle (41) fineness, grip length, amount of deflection, compression, bending modulus, critical force of compression value and stress distribution in binding fiber pin (41) compression process.

2, the method for fiber bending compression performance measurement as claimed in claim 1, it is characterized in that: set the high and low position of force transducer (21), change and stretch with upper grip (31) the adjustment method of clamping, lower gripper (5) is finished fiber needle (41) and is gripped, and carries out fiber needle (41) stretching and measures.

3, as the method for claim 1,2 described fiber bending compression performance measurements, it is characterized in that: by fenestration papery sample preparation template (43), according to required fiber needle (41) length, stick on the crosspiece of template (43) with double faced adhesive tape (42), again parallel the stretching of fiber is pasted on the double faced adhesive tape (42), cut on the dotted line, get fiber needle (41).

4, as the device of claim 1,2 described a kind of fiber bending compression performance measurements, it is characterized in that: stud with observable magnifier (13) for reducing air flow and vibration to measuring on the positive openable transparent panel in measurement chamber (1) that influences at one; Measure and to be provided with in the chamber (1) by comprising that mainly power measuring mechanism (2), multi-functional replaceable upper grip (3), lower gripper (5), optical imaging system (7), analog signal processing (8) and Computer Processing (9) and one partly are made up of by the sample platform (6) of micromotor (61) gear train drive computer control;

A, power measuring mechanism (2) are by force transducer (21) and with the multi-functional replaceable upper grip (3) of its flexible connection be positioned at sample platform (6) and go up lower gripper (5) formation rotatable, that move;

B, optical imaging system (7) are reached at the pointolite (76) with X, the setting of Y-axis angle by light source (71), object lens (74), CCD camera (75) and constitute;

C, analog signal processing (8) are by forming through collection and temperature compensation, filtering, amplifying circuit (81), the analog to digital conversion (82) of force transducer (21), displacement transducer (20) output simulating signal;

D, Computer Processing (9) are made up of data acquisition and computing module (91), parameter setting and control module (92) and control and transmission module (93).

5, the device of fiber bending compression performance measurement as claimed in claim 4 is characterized in that: inwall scribbles the color complementary with tested fiber needle (41) in measurement chamber (1); Force transducer (21) is a kind of high precision Micro-force sensor of cantilever beam structure; Multi-functional replaceable upper grip (3) comprises stretching uses upper grip (31) and compression upper grip (32) and chuck film (33) thereof; Lower gripper (5) is formed to guide rail (53) and rolling disc (54) by lower chuck (51) with the manual fine-tuning mechanism X axis guide rail (52) and the Y-axis of its interlock; Displacement transducer (20) function is to realize by micromotor (61) running number and cooperating of computer clock controller; Pointolite (76) is 30～60 ° with X, Y-axis angle.

6, as the device of claim 4,5 described fiber bending compression performance measurements, it is characterized in that: measure chamber (1) inwall scribble with the complementary color of tested fiber needle (41) be black; Pointolite (76) is 45 ° with X, Y-axis angle.

7, as the device of claim 4,5 described fiber bending compression performance measurements, it is characterized in that: chuck film (33) adopts superpolymer, sand paper.

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