Optical measurement system and application method for grinding

Abstract

The present invention discloses an optical measurement system and application method for grinding. The system includes an illumination light source, a support platform, a projection optical component, a display screen, and a computer. A workpiece to be processed is placed on the support platform. During grinding, the illumination light source illuminates the workpiece to be processed, and the projection optical component projects the image of the workpiece to be processed on the display plane of the display screen. The computer controls the display plane to display a pre-stored workpiece reference scale graphic, and positions it on the positioning baseline, compares the workpiece reference scale graphic with the projection of the workpiece to be processed, adjusts the displacement of the grinding equipment according to the comparison information, and performs grinding. When high-precision measurement is required, the present invention can partially enlarge the boundaries of the workpiece reference scale graphic and the workpiece projection image, and improve the accuracy by subdividing the display pixels, which can well meet the requirements of high-precision workpiece grinding for online detection.

Description

Technical Field

[0001] The invention relates to the field of precision mechanical processing equipment and geometric measurement, and in particular to an optical measurement system and an application method for real-time measurement of precision grinding. Background Art

[0002] Modern manufacturing industry has higher and higher requirements for the precision of mechanical processing equipment, and the precision of precision mechanical grinding is generally several microns or higher. When the precision machining level reaches the micron level, considering the wear of the grinding wheel and other factors, online measurement control must be considered. Optical projection image measurement technology is one of the important online measurement methods. Taking the currently common optical curve grinder as an example, the principle of the optical projection system for online measurement is the same as that of the contour projector. During measurement, according to the magnification of the projection system, it is necessary to accurately print out the film of the CAD design graphics, and the film is engraved with a very fine contour line using a line engraving device. This film is placed on the projection screen of the optical projection system, and the film graphics and the workpiece projection graphics are manually aligned. According to the difference between them, the grinding wheel processing feed amount is adjusted to achieve micron-level precision grinding of the workpiece. The magnification error of the printing film and the projection system in this way will directly affect the accuracy of the image grinding process, and it also requires a high projection magnification of the projection lens, and the application efficiency is not high.

[0003] The Chinese invention patent with the publication number of 01139045 provides a fast mold graphic measurement method with overall measurement characteristics. Compared with contact measurement or point-by-point coordinate measurement, the efficiency is greatly improved, and in principle it can be transplanted into ordinary grinding processing equipment. This method uses a CCD / CMOS image camera system to shoot the contour of the workpiece, which is displayed on a computer screen and compared with the workpiece CAD drawing to achieve image comparison measurement. However, there are three problems with this system: first, due to the size of the camera image sensor, the workpiece measurement range is very small; second, the boundary clarity of the imaging graphics is affected by the sensor pixel and the screen pixel size, and it is difficult to achieve high alignment accuracy; third, a fixed reference baseline is required, and the reliability of the entire system is not high. Although the existing computer graphics measurement method has the advantages of being fast and convenient, the image sensor pixel and the display pixel size have a great influence on the alignment accuracy of the image, and the accuracy is much lower than that of the general contour projector, and the practical application is also limited. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention combines computer image processing technology and the development of large-size computer transparent display technology in recent years, combines the fine alignment characteristics of transparent film with the fast and flexible characteristics of computer graphics, and proposes an optical measurement system and application method for precision grinding, which can conveniently realize high-precision (micron level) and larger-size online geometric measurement.

[0005] The purpose of the present invention is achieved through the following technical solutions: an optical measurement system for grinding, including an illumination light source, a support table, a projection optical component, a display screen, and a computer. The workpiece to be processed is placed on the support table. During grinding, the illumination light source illuminates the workpiece to be processed, and the projection optical component projects the image of the workpiece to be processed on the display plane of the display screen; the computer controls the display plane to display the pre-stored workpiece reference scale graphic, and positions it on the positioning baseline, compares the workpiece reference scale graphic with the projection of the workpiece to be processed, adjusts the displacement of the grinding equipment according to the comparison information, and performs grinding. The present invention realizes precise measurement of graphics by introducing a display screen, which can well meet the requirements of high-precision workpiece grinding for online detection.

[0006] Preferably, the position of the object support platform in three dimensions is adjustable, so that the position of the workpiece and the projection optical component can be adjusted according to different workpieces to be processed, so as to achieve workpiece focusing and make the projection of the workpiece on the transparent display screen more accurate.

[0007] Preferably, the projection optical component is a projection objective lens, one side of which is a plane and the other side is a convex surface. The workpiece to be processed is arranged in front of the plane, and at the focal position of the objective lens, the light passes through the convex surface and is focused onto the transparent display screen.

[0008] As a preferred embodiment, the projection optical assembly includes a projection lens and a beam splitter, the display screen adopts a transparent display screen, the projection light beam is transmitted to the beam splitter after passing through the projection lens, and is imaged on the transparent display screen after being reflected by the beam splitter, and a display screen backlight source is provided behind the beam splitter. With this structure, when projecting images, the illumination on the display screen is more uniform, which can achieve the purpose of beneficial measurement.

[0009] As a preferred embodiment, the projection optical assembly includes a front objective lens, a coaxial light beam splitter, a projection objective lens and a beam splitter. A coaxial light source is provided on one side of the coaxial light beam splitter. The light emitted by the coaxial light source is reflected by the coaxial light beam splitter and collimated on the surface of the workpiece to be processed by the front objective lens. The projection light beam reflected by the surface of the workpiece to be processed passes through the front lens, the coaxial light beam splitter, the projection objective lens and the beam splitter in sequence, and is imaged on a transparent display screen. By using this type of projection optical assembly, the total length of the optical path can be reduced when processing workpieces with concave or protruding structures.

[0010] Furthermore, the front objective lens adopts a bi-telecentric lens with a magnification of 1, which is lower than that of the projection objective lens, and can perform distortion and other aberration corrections.

[0011] As a preferred embodiment, the projection optical component includes a projection objective lens and a beam splitter. The projection light beam is transmitted to the beam splitter after passing through the projection objective lens, and is imaged on a conventional display screen after being transmitted through the beam splitter. An observation window is provided in the reflection direction of the beam splitter. With this optical component, the image formed on the display screen can be observed and measured through the observation window and the beam splitter.

[0012] Preferably, the optical measurement system for grinding processing adopts a box structure, with a protruding opening at the position of the object support platform, an observation window is provided at the corresponding box above the display screen, and a reading magnifying glass is provided at the observation window, or a camera is installed to simultaneously obtain the image of the reference scale graphic boundary and the corresponding workpiece graphic boundary, which is used to eliminate the interference of environmental factors, assist in locating the boundary of the workpiece projection image, and further improve the accuracy of the reading.

[0013] An optical measurement method for grinding, comprising the steps of:

[0014] Acquire a standard workpiece image displayed on a display plane of the standard workpiece; display a pre-stored standard workpiece reference scale corresponding to the design size of the standard workpiece on the display plane, calibrate the standard workpiece reference scale according to the standard workpiece image, and obtain the magnification of the projection optical component;

[0015] An image of the workpiece to be processed displayed on a display plane is acquired, a pre-stored reference scale of the workpiece to be processed corresponding to the design size of the workpiece to be processed is displayed on the display plane, the image of the workpiece to be processed and the reference scale of the workpiece to be processed are both positioned on the positioning baseline, and then an ideal boundary is calculated according to the calibrated magnification of the projection optical component, and a mobile grinding device is controlled to grind the workpiece to be processed according to a pixel difference value between the ideal boundary and the image of the workpiece to be processed, so as to achieve precision grinding.

[0016] Preferably, the standard workpiece reference scale is calibrated according to the standard workpiece image, and the steps are as follows:

[0017] (1-1) Obtain a standard workpiece image, the boundaries of which are A0 and B0 respectively. Display a pre-stored standard workpiece reference scale corresponding to the design size of the standard workpiece on the display plane. The boundaries of which are A0 and B0 respectively. s , B s ;

[0018] (1-2) Get the number of pixels m contained in the length of the standard workpiece reference scale s ;

[0019] (1-3) Compare the reference scale of the standard workpiece with the boundary A at one end of the standard workpiece image sand A′0, and obtain the pixel subdivision difference Δm1 between the two. Similarly, compare the reference scale of the standard workpiece and the boundary B at the other end of the standard workpiece. S and B0′, and obtain the pixel subdivision difference Δm2 between the two;

[0020] The calibrated magnification of the standard workpiece image relative to the standard workpiece is obtained as follows:

[0021]

[0022] Where L0 represents the actual length of the standard workpiece, and σ is the unit pixel size of the display screen.

[0023] The reference scale provided in the present invention is an image which is set according to the integer number of pixels of the display screen and is overlapped as much as possible with the projection image of the standard workpiece. The Δm1 and Δm2 read according to the difference between the two are both pixel subdivision differences less than 1, which is equivalent to subdividing the pixels of the display screen, thereby improving the alignment accuracy.

[0024] Preferably, the precision grinding process is achieved by:

[0025] (2-1) Displaying a pre-stored reference scale of the workpiece to be processed corresponding to the design size of the workpiece to be processed on the display plane, positioning the reference scale of the workpiece to be processed on the positioning baseline,

[0026] (2-2) According to the calibrated magnification of the projection optical component, the ideal boundary h′0 is calculated:

[0027] h′0=h0*β0;

[0028] Where h0 is the size of the workpiece to be processed after it is finished;

[0029] In pixels it is:

[0030] h′0=(m h +Δm h )*σ;

[0031] Among them, m h Indicates the size of the workpiece to be processed corresponding to the reference scale, which is an integer value, Δm h It is the pixel subdivision value between the ideal boundary and the reference scale of the workpiece to be processed;

[0032] (2-3) Obtain an image of the workpiece to be processed displayed on a display plane, calculate the pixel difference value ε between the workpiece and the ideal boundary, and grind the workpiece by controlling the mobile grinding equipment according to the value so that ε approaches 0, thereby completing the precision grinding of the workpiece.

[0033] Preferably, a reading magnifier or camera is provided at the observation window, and the pixel subdivision value and the pixel difference value are read to the next digit through the reading magnifier or camera, thereby further reducing the alignment error caused by the pixel unit size of the display screen, improving the accuracy of the reading, and more accurately locating the boundary of the image of the workpiece to be processed.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] 1. The present invention projects the projection of the workpiece to be processed directly onto a transparent computer display screen. When the aberration of the projection lens is well corrected, the boundary position of the workpiece projection is clearly determined on the display screen, regardless of the display pixels of the display screen. When the present invention performs graphic boundary measurement, the computer displays the reference scale image of the workpiece on the transparent display screen based on the pre-calibrated data. Since the projection of the workpiece is also on the transparent display screen, the positioning reference point or line of the projection image can be determined conveniently and quickly. The size of the reference scale graphic can be determined by quick calibration, and the requirements for the magnification of the projection lens are relatively loose. Appropriately enlarging the workpiece reference scale for local comparison can further reduce the quantization error generated by the pixel size unit of the display screen, effectively improve the online measurement and control accuracy, and correspondingly expand the measurement range of the workpiece.

[0036] 2. The present invention has relatively loose requirements on the magnification of the projection objective lens. Calibration and adjustment can be completed quickly on a transparent display screen. The workpiece reference map is set according to the workpiece design value and the positioning is quickly subdivided. This solves the problem that the magnification of the traditional contour projector film is heavily dependent on the projection lens, and the system is more reliable and convenient. The present invention solves the field of view and accuracy limitations of the image sensor when using a conventional projection screen. By setting a standard workpiece reference scale and a reference scale for the workpiece to be processed, the present invention can refine the reading of display screen pixels and effectively reduce the image edge alignment error caused by display screen pixels. According to the calibrated magnification of the projection optical component, the ideal boundary is calculated, and grinding is performed according to the pixel difference value between the ideal boundary and the image of the workpiece to be processed, and its precision is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the optical measurement system for grinding shown in Example 1.

[0038] Figure 1a This is the P1 view during the calibration process of Example 1.

[0039] Figure 1b This is the P1 view during the grinding process of Example 1.

[0040] Figure 1c yes Figure 1b Enlarged view of point S in the middle.

[0041] Figure 1d This is the P2 direction view during the grinding process of Example 1.

[0042] Figure 2 It is a schematic diagram of the structure of the optical measurement system for grinding processing with a backlight source shown in Example 2.

[0043] Figure 3 It is a schematic diagram of the structure of the optical measurement system for grinding processing with a front objective lens and a coaxial light source shown in Example 3.

[0044] Figure 4 It is a schematic structural diagram of an optical measurement system for grinding processing shown in Example 4, which uses a conventional display screen instead of a transparent display screen.

[0045] In the figure: 1-illumination light source, 2-object holder, 3-workpiece, 4-projection objective lens, 5-transparent display screen, 6-computer, 7-grinding wheel, 8-standard workpiece image, 9-standard workpiece reference scale, 10-display screen cursor, 11-image of workpiece to be processed, 12-workpiece design reference drawing, 13-reference scale of workpiece to be processed, 14-ideal boundary, 15-transparent display screen backlight source, 16-beam splitter, 17-front objective lens, 18-coaxial light source, 19-coaxial light beam splitter, 20-conventional display screen. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0047] Example 1

[0048] like Figure 1 As shown, this embodiment discloses an optical measurement system for grinding processing, which includes an illumination light source 1, a support table 2, a projection lens 4, a display screen 5, a computer 6 and a display screen backlight 13, etc., wherein the display screen 5 is a transparent display screen. The illumination light source 1, the support table 2, the projection lens 4, and the transparent display screen 5 are on the same optical path. When calibrating or grinding processing is performed, the workpiece is first placed on the support table 2, and the computer 6 can control the support table 2 to move in three dimensions to achieve workpiece focusing. During measurement, the illumination light source 1 illuminates the workpiece, and the projection lens projects the workpiece 3 to be processed onto the display plane of the transparent display screen. Each structure is described in detail below.

[0049] In this embodiment, the illumination light source 1 is a transmission light source. The central axis of the illumination light beam is in a straight line with the center of the workpiece and the optical axis of the projection objective lens.

[0050] In this embodiment, the object support table 2 includes a three-dimensional motion mechanism and a support frame. The workpiece is fixed on the support frame during grinding. There are many ways to fix it, such as by embedding a snap-fit ​​method, by threaded fixing method, by magnetism or starting suction cup fixing, etc., which will not be described in detail here.

[0051] The computer 6 in this embodiment can be a common computer, an industrial computer, a notebook computer, a single-chip microcomputer or other controller, and its functions mainly include controlling the movement of the object-carrying platform, controlling the display, processing and storage of images on the transparent display screen, etc. In addition, according to actual needs, the opening and closing of other electronic control components can also be controlled.

[0052] In this embodiment, the transparent display screen is connected to a computer, and the image of the workpiece to be processed is directly projected on the transparent display screen. At the same time, the transparent display screen also receives information transmitted by the computer to display the reference scale graphics, which are usually displayed using CAD drawings. The user can move the CAD drawing or projection of the reference scale on the transparent display screen for calibration or measurement. Since the workpiece image is directly imaged on a transparent display screen, the limitation of the measurement range and accuracy on the workpiece image obtained by the camera in the past is avoided.

[0053] In order to avoid the influence of ambient light, temperature and humidity, etc., the optical measurement system for grinding processing in this embodiment adopts a box structure, and an extension is left at the position of the support table 2 for placing or taking out the standard workpiece and the workpiece to be processed. An observation window is provided at the corresponding box above the transparent display screen for users to compare and calibrate the position of the workpiece to be processed. In addition, a reading magnifying glass can also be provided at the observation window to improve the human eye's ability to distinguish the boundary position. Alternatively, a camera that can simultaneously obtain the image of the reference scale graphic boundary and the corresponding workpiece graphic boundary is installed to assist in positioning.

[0054] The optical measurement method for grinding in this embodiment comprises the following steps:

[0055] (1) obtaining a standard workpiece image displayed on a display plane; displaying a pre-stored standard workpiece reference scale corresponding to the design size of the standard workpiece on the display plane, calibrating the standard workpiece reference scale according to the standard workpiece image, and obtaining a magnification of the projection optical component;

[0056] (2) an image of the workpiece to be processed displayed on a display plane is obtained, a pre-stored reference scale of the workpiece to be processed corresponding to the design size of the workpiece to be processed is displayed on the display plane, the image of the workpiece to be processed and the reference scale of the workpiece to be processed are positioned on the positioning baseline, and then an ideal boundary is calculated according to the calibrated magnification of the projection optical component, and a moving grinding wheel is controlled to grind the workpiece to be processed according to the pixel difference value between the ideal boundary and the image of the workpiece to be processed, so as to realize precision grinding.

[0057] The reference scales of the present invention are all set according to the integer number of pixels of the display screen. When displayed on the display plane, the boundaries are accurate integer pixel boundaries. Compared with the boundaries of the projected image, the pixel size of the transparent display screen can be used as the minimum division unit to achieve graphic measurement.

[0058] Specifically, the above method is further explained by taking a length measurement as an example.

[0059] 1. Use standard workpieces to calibrate the system and obtain the magnification of the projection optical component.

[0060] The display plane is an array composed of multiple pixels. The pixels can be regarded as small squares. These small squares have a clear position and assigned color values. The color and position of the small squares determine the appearance of the image and are regarded as indivisible units in the entire image. In practical applications, when the projected image falls on the display screen, it will not fall exactly on the boundary of a pixel and occupy a complete square. In fact, there will be more or less misalignment. If it is measured only according to the number of complete pixels occupied, it will inevitably lead to inaccurate measurement calculations. This step is mainly to obtain the standard workpiece image displayed on the display plane; set a standard workpiece reference scale on the display plane according to integer pixels. The reference scale is overlapped with the standard workpiece projection map as much as possible. By obtaining the difference between the two ends of the reference scale and the two ends of the standard workpiece map, the length of the reference scale is adjusted to obtain the accurate size of the standard workpiece projection map on the display screen, and the magnification of the measurement system is calculated.

[0061] See also Figure 1a , b, c, d. The specific steps are as follows:

[0062] (1) A standard workpiece (A0B0) with a known length L0 is fixed on the workpiece support 2, the illumination light source 1 illuminates the standard workpiece 3, and the objective lens is adjusted so that the projection image 8 of the standard workpiece 3 is clearly projected on the display plane of the transparent display screen 5. In the figure, reference numeral 10 represents the display screen cursor.

[0063] (2) On the display screen 5, a standard workpiece reference scale 9 (A) is set to coincide with the standard workpiece image 8 as closely as possible according to the integer number of display screen pixels. s B s), record the number of pixels contained in the reference scale length as m s .

[0064] (3) Zoom in and observe the difference between the boundary of the projection image 8 of the standard workpiece 3 and the boundary of the standard workpiece reference scale 9, and obtain the differences (in pixels) at both ends as Δm1 and Δm2, respectively. From this, the magnification of the system can be calibrated as:

[0065]

[0066] In formula (1), σ is the pixel unit size of the display screen.

[0067] 2. Carry out precision grinding on the workpiece to be processed.

[0068] This step mainly involves obtaining the image 11 of the workpiece to be processed displayed on the display plane; determining the positioning baseline, and displaying the workpiece design reference diagram 12 of the workpiece to be processed on the display plane according to the parameters calibrated by the optical measurement system, which is equivalent to the reference scale 12 of the workpiece to be processed. Taking the observation of the S area of ​​the workpiece to be processed on the display plane as an example, the ideal boundary 14 of the workpiece to be processed on the display screen is set, and the grinding wheel 7 is controlled to move to grind the workpiece to be processed, so that the projection image of the workpiece to be processed can finally coincide with the ideal boundary 14, that is, the grinding process of the workpiece is completed. The specific steps are as follows:

[0069] (1) The workpiece 3 to be precisely machined is fixed on the workpiece support. By focusing, the outline of the workpiece 3 to be machined is clearly imaged on the transparent display screen 5. If the design height h0 of the workpiece to be machined corresponds to the display screen S, according to the system magnification, the height of the workpiece design size on the display screen at that location can be obtained as

[0070] h′0=h0*β0 (2)

[0071] Or in pixels

[0072] h′0=m*σ=(m h +Δm h )*σ (3)

[0073] Where: The ideal boundary S on the display screen actually consists of two parts, namely the integer number of pixels m corresponding to the height of the reference scale h and pixel subdivision value Δm h .

[0074] (2) Obtain the pixel difference value ε between the image boundary (at S) of the workpiece to be processed and the ideal boundary, and grind the workpiece by controlling the moving grinding wheel according to the value so that ε approaches 0, that is, the precision grinding of the workpiece at S is completed.

[0075] The requirements of the present invention on the magnification of the projection objective lens are relatively loose, and the calibration of the system magnification can be quickly completed on the transparent display screen. The workpiece reference map is set according to the workpiece design value and the positioning is quickly subdivided, which well solves the problem that the magnification of the traditional contour projector film is heavily dependent on the projection lens, and the system is more reliable and convenient. The following is a further description of the method for improving the measurement accuracy of the present invention. During the initial processing of the present invention, the grinding wheel only needs to be ground according to the reference scale of the workpiece to be processed on the display screen. During fine grinding, due to the pixel size of the display screen, the boundary of the reference scale graphic of the workpiece to be processed will produce a large alignment quantization error. At this time, the uncertainty caused by the integer alignment of the display screen pixels is reduced by subdividing the display pixels, thereby improving the processing accuracy.

[0076] It is worth noting that the alignment of the workpiece image boundary and the reference scale graphic boundary can be completed by manual judgment alone. A camera that can simultaneously obtain the reference scale boundary and the corresponding workpiece graphic boundary image to be processed can also be installed, and the camera can be used to independently realize the alignment of the workpiece image boundary and the reference scale graphic boundary. Of course, it can also be completed by manual judgment combined with camera assistance.

[0077] The present invention can refine the scale value of the workpiece corresponding to the unit pixel of the transparent display screen by selecting a reference scale and appropriately enlarging the reference scale, thereby reducing the quantization error of the pixel size of the display screen on the measurement result. The present invention can effectively reduce the quantization error of the pixel size of the display screen on the measurement result by selecting a reference scale and further subdividing and compensating the two ends of the reference scale.

[0078] Example 2

[0079] The first embodiment is only a basic device and a basic method of use of the present invention. In practical applications, the present invention can meet different usage requirements through obvious changes and optimizations. In the first embodiment, the projection light is also the backlight of the transparent display screen. In order to make the display screen display better, this embodiment adds a dedicated transparent display screen backlight source 15.

[0080] At the same time, the projection optical component of this embodiment includes a projection objective lens 4 and a beam splitter 16. The display screen adopts a transparent display screen. The projection light beam is transmitted to the beam splitter 16 after passing through the projection objective lens 4, and is imaged on the transparent display screen after being reflected by the beam splitter 16. The display screen backlight source 15 is arranged behind the beam splitter 16.

[0081] In this embodiment, the beam splitter 16 has partial reflection and partial transmission functions. The projection light beam is reflected by the beam splitter and imaged on the transparent display screen, and the light source is lit at the same time. The light passes through the beam splitter to illuminate the transparent display screen. While the normal projection imaging is being performed, the illumination on the transparent display screen is more uniform, achieving the purpose of beneficial measurement.

[0082] Example 3

[0083] This embodiment has the same structure as Embodiment 1 except for the following features:

[0084] In actual workpiece grinding, in order to take into account the convenience and safety needs of the workpiece grinding, the system is required to have a larger working distance (i.e., the distance between the workpiece and the projection lens). For this reason, this embodiment proposes that a low-magnification front lens 17 can be added in front of the projection lens 4. The structure is as follows Figure 3 shown.

[0085] In this embodiment, the front objective lens is designed as a large working distance bi-telecentric lens with a magnification of 1, and distortion and other aberration corrections are performed. Due to the use of the front objective lens, the front working distance of the projection lens is shortened, and the total length of the projection optical path is compressed.

[0086] In this embodiment, the projection optical component has a coaxial light source 18, which is reflected by a coaxial light splitter 19 and collimated on the workpiece surface by a front objective lens 17, and then projected onto a transparent display screen after being reflected by the workpiece surface. The projection optical component has a coaxial light source to ensure the geometric measurement of the surface graphic structure.

[0087] Example 4

[0088] This embodiment has the same structure as Embodiment 1 except for the following features:

[0089] See also Figure 4 In this embodiment, the transparent display screen 5 is replaced with a conventional display screen 20, and the basic functions of the embodiment 1 can also be realized. The projection optical assembly includes a projection lens 4 and a beam splitter 16. The projection light beam is transmitted to the beam splitter 16 after passing through the projection lens 4, and is imaged on the conventional display screen 20 after being transmitted through the beam splitter 16. The image is then conveniently observed and measured through the beam splitter 16. Considering that the observation window is far away from the display screen, an auxiliary camera or a measuring magnifying glass can be set at the observation window to assist in measurement if necessary.

[0090] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An optical measurement system for grinding, characterized in that: The device comprises an illumination light source, a support table, a projection optical component, a display screen, and a computer. The workpiece to be processed is placed on the support table. During grinding, the illumination light source illuminates the workpiece to be processed, and the projection optical component projects the image of the workpiece to be processed onto the display plane of the display screen. The computer controls the display plane to display a pre-stored workpiece reference scale graphic and positions it on the positioning baseline, compares the workpiece reference scale graphic with the projection of the workpiece to be processed, adjusts the displacement of the grinding equipment according to the comparison information, and performs grinding. The position of the object support platform in three dimensions is adjustable; The projection optical assembly includes a projection lens and a beam splitter. The display screen adopts a transparent display screen. The projection light beam is transmitted to the beam splitter after passing through the projection lens, and is imaged on the transparent display screen after being reflected by the beam splitter. A display screen backlight source is provided behind the beam splitter, and an observation window is provided in the reflection direction of the beam splitter. The projection optical assembly comprises a front objective lens, a coaxial light beam splitter, a projection objective lens and a beam splitter. A coaxial light source is provided on one side of the coaxial light beam splitter. Light emitted by the coaxial light source is reflected by the coaxial light beam splitter and collimated on the surface of the workpiece to be processed by the front objective lens. The projection light beam reflected by the surface of the workpiece to be processed passes through the front lens, the coaxial light beam splitter, the projection objective lens and the beam splitter in sequence, and is imaged on the transparent display screen. The optical measurement system for grinding processing adopts a box structure, with an extension opening left at the position of the object support platform, an observation window is provided at the box corresponding to the top of the display screen, a reading magnifying glass is provided at the observation window, or a camera is installed to simultaneously obtain the reference scale graphic boundary and the corresponding workpiece graphic boundary image.

2. The optical measuring system for grinding according to claim 1, characterized in that: The lens of the front objective lens adopts a double telecentric lens with a magnification of 1, which is lower than the projection objective lens.

3. The optical measurement method of the optical measurement system for grinding according to claim 1 or 2, characterized in that: Includes steps: Acquire a standard workpiece image displayed on a display plane; Displaying a pre-stored standard workpiece reference scale corresponding to the design size of the standard workpiece on the display plane, calibrating the standard workpiece reference scale according to the standard workpiece image, and obtaining the magnification of the projection optical component; Calibrate the standard workpiece reference scale according to the standard workpiece image. The steps are as follows: (1-1) Obtain a standard workpiece image, the boundaries of which are A0 and B0 respectively. Display a pre-stored standard workpiece reference scale corresponding to the design size of the standard workpiece on the display plane. The boundaries of which are A0 and B0 respectively. s , B s ; (1-2) Get the number of pixels m contained in the length of the standard workpiece reference scale s ; (1-3) Compare the reference scale of the standard workpiece with the boundary A at one end of the standard workpiece image s and A′0, and obtain the pixel subdivision difference Δm1 between the two. Similarly, compare the reference scale of the standard workpiece and the boundary B at the other end of the standard workpiece. S and B0′, and obtain the pixel subdivision difference Δm2 between the two; The calibrated magnification of the standard workpiece image relative to the standard workpiece is obtained as follows: Where L0 represents the actual length of the standard workpiece, and σ is the unit pixel size of the display screen; An image of the workpiece to be processed displayed on a display plane is acquired, a pre-stored reference scale of the workpiece to be processed corresponding to the design size of the workpiece to be processed is displayed on the display plane, the image of the workpiece to be processed and the reference scale of the workpiece to be processed are both positioned on the positioning baseline, and then an ideal boundary is calculated according to the calibrated magnification of the projection optical component, and a mobile grinding device is controlled to grind the workpiece to be processed according to a pixel difference value between the ideal boundary and the image of the workpiece to be processed, so as to achieve precision grinding.

4. The optical measurement method according to claim 3, characterized in that: To achieve precision grinding, the steps are: (2-1) Displaying a pre-stored reference scale of the workpiece to be processed corresponding to the design size of the workpiece to be processed on the display plane, positioning the reference scale of the workpiece to be processed on the positioning baseline, (2-2) According to the calibrated magnification of the projection optical component, the ideal boundary h′0 is calculated: h′0=h0*β0; Where h0 is the size of the workpiece to be processed after it is finished; In pixels it is: h′0=(m h +Δm h )*s; Among them, m h Indicates the size of the workpiece to be processed corresponding to the reference scale, which is an integer value, Δm h It is the pixel subdivision value between the ideal boundary and the reference scale of the workpiece to be processed; (2-3) Obtain an image of the workpiece to be processed displayed on a display plane, calculate the pixel difference value ε between the workpiece and the ideal boundary, and grind the workpiece by controlling the mobile grinding equipment according to the value so that ε approaches 0, thereby completing the precision grinding of the workpiece.

5. The optical measurement method according to claim 3, characterized in that: A reading magnifier or camera is provided at the observation window, through which the pixel subdivision value and the pixel difference value are read to the next digit.

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