TWI393854B - The method of the optical system to measure the actual contact area of ​​the - Google Patents

Description

Method for measuring actual contact area by optical system

The invention relates to a measuring method, in particular to a method for accurately measuring the actual contact area after applying a force by using a controlled force applying condition combined with an optical interference principle and an image analyzing technique.

No matter how smooth the surface of the object is, if it is observed under a microscope, the surface will be uneven. In terms of modern processing technology, even with high-precision grinding machinery, the roughness of the metal surface is still about 0.1um. Therefore, if it is observed by the naked eye, it can be seen that the entire surface is in full contact, but in reality it is only a very small number. The spikes touch each other. Referring to Fig. 1, an element 9 having a surface having a plurality of rough portions 91, the external contact area is the area of the surface, and the contact area of the rough portions 91 with the outside relative to the external contact area The sum is the actual contact area. In general, the actual contact area is only one to one ten thousandth of the external contact area, and varies with the size of the load.

In such a small area to withstand the full load, the pressure per unit area is very large, the contact point will be plastically deformed, the peak of the contact point is crushed, the contact surface is closer, and the contact point is adhered due to the molecular force. When the two contact surfaces move relative to each other, the adhesive portion will be sheared, and the force required for the shearing is friction. Therefore, the amount of friction is determined by the actual contact area.

Generally, the actual contact area is measured by the electric resistance method, and only the energy of a workpiece having a rough surface under different load conditions, the actual contact area and the appearance area are measured. The ratio of the actual contact area distribution is not known, and when measured by the electric resistance method, the non-conductive substance cannot be measured.

Therefore, how to find a not only measurable metal material, the actual contact area of the surface of the non-metallic material, and without destroying the object to be tested in the measurement process, thereby reducing the measurement cost and improving the repeatability of the measurement, One of the topics that the field is trying to solve.

Accordingly, it is an object of the present invention to provide a method of measuring an actual contact area with an optical system.

Therefore, the method for measuring the actual contact area by the optical system of the present invention can be used for measuring and calculating the actual contact area of the rough surface of the object to be tested having a rough surface, the method comprising: a preparation step, a step of advancing, An image capture step and a data processing step.

The preparation step is to prepare a test object, the test object is placed on the stage of the optical microscope with the rough surface facing the observation objective lens, and an optical glass plate is disposed on the object to be tested and the observation objective lens. between. The advancing step is to apply a positive thrust perpendicular to the stage under the stage, so that the stage approaches the objective lens of the optical microscope, and the surface roughness of the object to be tested actually contacts the optical Glass plate to the set level. The image capturing step is an image capturing operation of the actual contact area after the object to be tested is stopped in contact with the optical glass plate by an image capturing device. The data processing step is to calculate the number of pixels occupied by the actual contact area in an image captured by the image data processing device from the image capturing device, and multiply the pixel number by the correction per unit pixel. Numerically, the rough surface of the object to be tested is substantially in contact with the optical glass The contact area of the board.

The effect of the invention is that the object to be tested is brought into contact with the optical glass plate via a positive thrust, and the forward thrust is continuously applied, and when the forward thrust is not greater than plastically deforming the rough portion, After the image capturing and data processing, the actual area of the rough portion of the object to be tested can be obtained, and the actual distribution of the roughness can be obtained simultaneously through the captured image.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to Fig. 2, when implementing the method of measuring the actual contact area by the optical system of the present invention, an optical measuring system 1 is first prepared.

The optical measuring system 1 includes an optical microscope 11, a light source device 12, an image capturing device 13, a propulsion device 14, and a data processing device 15.

The optical microscope 11 includes a stage 111, an observation objective 112, a fixing portion 113 interposed between the stage 111 and the observation objective 112, and an optical glass plate 114 fixed to the fixing portion 113.

The light source device 12 has a light source 121, a polarizing mirror 122, a spatial filter 123, a lens group 124, and a fiber optic hose 125. In the preferred embodiment, the light source 121 can be For the He-Ne Laser or the white light, the light source 121 can perform a process of filtering out clutter, reducing spots, and the like through the polarizer 122 to the spatial filter 123, and then entering the fiber through the lens group 124. In the hose 125.

The image capturing device 13 has a high speed camera 131 into which a laser entering the fiber optic hose 125 is introduced into the high speed camera 131 as an observation light source.

The propulsion device 14 includes a pressing unit 141 and a measuring unit 142. The pressing unit 141 has a lever 143. One end of the lever 143 is connected to the bottom of the storage table 111, and the other end has a load portion 144. A pair of points 145 are disposed between the two ends of the lever 143 to place a load on the load portion 144. w, the load is applied in a lever manner, and the end connected to the bottom of the stage 111 is driven to press the stage 111 in the direction of the observation objective lens 112. In the preferred embodiment, the ratio of the length of the load applied to the load end of the lever 143 is 5:1, the distance from the load portion 144 to the fulcrum 145 is 175 mm, and the fulcrum 145 is connected to the connection. The distance from the bottom end of the stage 111 is 35 mm; The measuring system 142 has a load meter 146 and an eddy current displacement transducer 147, which can accurately measure the dynamic load applied by the pressing unit 141, and the direction of the force applied is perpendicular to the stage 111. The eddy current displacement meter 147 can monitor the initial pressing position; it can also accurately measure the amount of displacement per unit time during extrusion, and infer the extrusion speed.

Referring to FIG. 2 and FIG. 3, a preferred embodiment of the method for measuring an actual contact area by using an optical system includes a preparation step 51, a step of advancing 52, an image capturing step 53, and a data processing step. 54.

First, the preparation step 51 is performed to prepare a sample 2 having a plurality of rough portions on the surface, and the object to be tested 2 is ultrasonically shaken and washed in advance. The surface roughness of the object 2 to be tested is oriented in the direction of the optical glass plate 114, And placed on the stage 111.

Then, the advancing step 52 is performed, and a forward thrust is applied via the propulsion device 14 connected to the bottom of the stage 111. The propulsion device 14 can control the forward thrust by adjusting the pressing position and the pressing speed. The stage 111 carrying the object to be tested 2 pushes against the optical glass plate 114 until the forward thrust is not greater than plastically deforming the roughness, thereby generating a rough portion and the optical glass. The actual contact area that the plate 114 actually contacts.

Then, the image capturing step 53 is performed, and the actual contact area is image-captured by the high-speed camera 131 of the image capturing device 13 to obtain a still image of an actual contact area.

Finally, the data processing step 54 is performed, and the actual area of the rough portions is obtained by measuring the actual contact area distribution by the image of the actual contact area via the image data processing device 13. In the preferred embodiment, an image of the actual contact area of the object 2 to be in contact with the optical glass plate 114 is captured by the image capturing device 13 and then obtained by the image analysis software. The number of pixels in the actual contact area is then multiplied by the corrected value of the actual size of each unit of the pixel, and finally the contact area can be obtained. The correction value can be obtained by capturing a corrected object of a known size, and then using the preparation step, the advancing step and the image capturing step to analyze the pixel size occupied by the corrected object, thereby obtaining each The actual size represented by the prime number is plotted and the correction value is derived.

Here, it should be noted that when the forward thrust is too large, the contact points of the rough portions with the optical glass plate 114 are plastically deformed, so that the peak of the contact point is crushed, thereby causing the measured contact area. Close to the roughness The entire area is distorted by the measurement result. Therefore, preferably, the positive force should be a force not greater than the plastic deformation of the object 2 to be tested.

In the preferred embodiment, different forward thrusts can also be controlled, the dynamic load applied by the pressing unit 141 is accurately measured by the load meter 146, and the initial crushing position is monitored using the eddy current displacement meter 147. Accurately measuring the amount of change in displacement per unit time during extrusion, and inferring the extrusion speed, not only can control the object to be tested 2 to slowly approach the optical glass plate 114, thereby avoiding the collision effect, and thereby different The positive thrust obtains different actual contact areas, and then the statistical method and the curve fitting method are used to obtain the relationship between the forward thrust and the actual contact area.

In summary, the present invention uses a positive thrust to gradually contact the rough portion of the object 2 with the optical glass plate 114 by a method of optically measuring the actual contact area, and controls the forward thrust in the forward direction. The contact area of the rough portion and the optical glass plate 114 can be measured under the condition that the thrust is not greater than the plastic deformation of the rough portion; the measuring method is simple, and not only the metal material but also the non-metal material can be used, and the measurement is performed. There is no need to destroy the test object 2 during the process, thereby reducing the measurement cost and improving the repeatability of the measurement. In addition, the actual distribution of the roughness can be obtained simultaneously at the time of measurement, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1‧‧‧Optical measurement system

11‧‧‧Light microscope

111‧‧‧Stores

112‧‧‧ Observation objective

113‧‧‧ fixed department

114‧‧‧Optical glass plate

12‧‧‧Light source device

121‧‧‧Light source

122‧‧‧polar mirror

123‧‧‧ Spatial Filter

124‧‧‧ lens group

125‧‧‧Fiber hose

13‧‧‧Image capture device

131‧‧‧High speed camera

14‧‧‧Protection device

141‧‧‧Extrusion unit

142‧‧‧Measurement unit

143‧‧‧Leverage

144‧‧‧Loading Department

145‧‧ fulcrum

146‧‧‧ load meter

147‧‧‧ eddy current displacement meter

15‧‧‧Image data processing device

2‧‧‧Test object

51‧‧‧Steps

52‧‧‧Steps

53‧‧‧Steps

54‧‧‧Steps

1 is a schematic view showing an object having a plurality of rough portions on a surface; FIG. 2 is a schematic view showing an optical measuring system in the method for measuring an actual contact area by an optical system of the present invention; and FIG. 3 is a flow BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of a method of measuring an actual contact area by an optical system in accordance with the present invention is illustrated.

Step 51‧‧‧ Prepare a test object having a rough surface, place the rough surface toward the objective lens, place it on the stage, and place the optical glass plate between the optical microscope and the object to be tested

Step 52‧‧‧ A positive thrust perpendicular to the stage is applied from the underside of the stage by a propulsion device to bring the stage closer to the objective lens to the surface roughness of the object to be tested Contacting the optical glass plate, and the forward thrust is not greater than plastically deforming the roughness

Step 53 ‧ ‧ an image capturing device picks up an image of the object to be tested from the observation lens of the optical microscope and contacts the optical glass plate to stop contact

Step 54‧‧‧ Calculate the number of pixels occupied by the actual contact area from the image captured by the image capturing device by the image data processing device, and multiply the number of pixels by the corrected value of the prime number per unit pixel The contact area of the rough surface of the object to be tested substantially in contact with the optical glass plate can be obtained, wherein the correction value can be obtained by taking a correction object of a known size, and then using the preparation step, the step of advancing and The image capturing step analyzes the size of the pixel occupied by the corrected object, thereby obtaining the actual size represented by each pixel number, and deducing the corrected value.

Claims (4)

A method for measuring an actual contact area by an optical system, which can be used for measuring and calculating a real area of a rough surface of a test object having a rough surface, the method comprising: a preparation step of placing the test object in a An optical microscope plate is disposed between the optical microscope and the object to be tested, and the rough surface of the object to be tested is oriented toward the optical glass plate; a propulsion step is performed by a propulsion device Applying a positive thrust perpendicular to the stage from below the stage, causing the stage to approach the objective lens of the optical microscope, until the surface roughness of the object to be tested actually contacts the optical glass plate, and The forward thrust is not greater than plastic deformation of the rough portion; an image capturing step is performed by an image capturing device that picks up the object to be tested from the optical microscope and stops the contact with the optical glass plate. An image of the actual contact area; and a data processing step of calculating an actual contact area by an image data processing device from the image captured by the image capturing device The prime number is obtained by multiplying the prime number by the correction value per unit of the prime number, and the contact area of the rough surface of the object to be tested substantially in contact with the optical glass plate can be obtained, wherein the correction value can be taken by shooting The correction object of a known size is further analyzed by the preparation step, the advancing step and the image capturing step to analyze the pixel size occupied by the corrected object, thereby obtaining the actual size represented by each pixel number. And calculate the correction value. The method for measuring an actual contact area by an optical system according to the first aspect of the patent application, wherein the image capturing device has a light source selected from a white light or a krypton-helium laser. A method for measuring an actual contact area by an optical system according to the first aspect of the patent application, wherein the propulsion device applies a forward thrust in a lever manner, and places a load on one end of the lever to force the object to be tested to the optical glass plate. extrusion. A method for measuring an actual contact area by an optical system according to the third aspect of the patent application, wherein a ratio of a rod end of the lever application load end to a force end of the object to be tested is 5:1, and the object to be tested The stage is provided with a load meter whose direction of force is perpendicular to the optical glass plate.