阅读说明：本技术 一种机械零部件轮廓测量装置 (Contour measuring device for mechanical parts ) 是由 李琦 向阳 董萌 张合 闫帅 于 2019-07-10 设计创作，主要内容包括：本发明公开一种机械零部件轮廓测量装置,涉及工业测量技术领域。该装置包括物方远心系统和像方远心系统；物方远心系统为前固定组,像方远心系统包括：变倍组,补偿组和后固定组。该装置通过移动变倍组与补偿组,同时双组联动,在单位工作距离内,保持物像方放大倍率不变。物方远心系统自身可消除物方由于调焦不准确带来的误差,像方远心系统可以消除像方调焦不准引入的测量误差。综合物像方远心作用,配以背光源照射,可实时将在线加工的不同尺寸(30-90mm)的零件轮廓图像通过影像系统采集到计算机中,与加工图纸比对,可直观、清晰的完成产品表面轮廓的检测及修正,全面提高工人的加工效率,保证测量精度。(The invention discloses a device for measuring the contour of a mechanical part, and relates to the technical field of industrial measurement. The device comprises an object space telecentric system and an image space telecentric system; object space telecentric system is preceding fixed group, and image space telecentric system includes: a zoom group, a compensation group and a post-fixation group. The device keeps the magnification of an object image space unchanged within a unit working distance by moving the zoom group and the compensation group and simultaneously linking the two groups. The object space telecentric system can eliminate errors caused by inaccurate focusing of the object space, and the image space telecentric system can eliminate measurement errors caused by inaccurate focusing of the image space. The image space telecentric effect is combined with the backlight source for irradiation, so that the contour images of the parts with different sizes (30-90mm) processed on line can be collected into a computer in real time through an image system and compared with a processing drawing, the detection and correction of the surface contour of the product can be visually and clearly completed, the processing efficiency of workers is comprehensively improved, and the measurement precision is ensured.)

1. A machine part profile measuring device, comprising: an object space telecentric system, an aperture diaphragm and an image space telecentric system;

the object space telecentric system comprises a front cemented lens group and a rear cemented lens group; the image space telecentric system comprises a zoom group, a compensation group and a rear fixed group;

the front gluing lens group, the rear gluing lens group, the aperture diaphragm, the zoom group, the compensation group and the rear fixing group are arranged in sequence from an object space to an image space;

and the exit pupil position of the object-side telecentric system is superposed with the entrance pupil position of the image-side telecentric system.

2. The mechanical part contour measuring device as recited in claim 1, wherein said front glue lens group comprises a first lens and a second lens;

the first lens is a positive meniscus lens with negative focal power, and the convex surface of the first lens faces the object space;

the second lens is a biconvex lens with positive focal power;

the concave surface of the first lens is cemented with one convex surface of the second lens.

3. The mechanical part profile measuring device as recited in claim 1, wherein the rear glue mirror group includes a third lens and a fourth lens;

the third lens is a positive meniscus lens with negative focal power, and the convex surface of the third lens faces the object space;

the fourth lens is a biconvex lens with positive focal power;

the concave surface of the third lens is cemented with one convex surface of the fourth lens.

4. The mechanical part profile measuring device of claim 1, wherein the variable power group includes a fifth lens and a sixth lens;

the fifth lens is a negative meniscus lens with positive focal power, and the concave surface of the fifth lens faces the object space;

the sixth lens is a negative meniscus lens with negative focal power, and the concave surface of the sixth lens faces the object space;

the convex surface of the fifth lens is glued with the concave surface of the sixth lens.

5. The mechanical part profile measuring device of claim 1, wherein the compensation group includes a seventh lens and an eighth lens;

the seventh lens is a biconvex lens with positive focal power;

the eighth lens is a negative meniscus lens with negative focal power, and the concave surface of the eighth lens faces the object space;

one convex surface of the seventh lens is cemented with the concave surface of the eighth lens.

6. The mechanical part contour measuring device of claim 1, wherein the rear mounting group includes a ninth lens and a tenth lens;

the ninth lens is a positive meniscus lens with positive focal power, and the concave surface of the ninth lens faces the object space;

the tenth lens is a positive meniscus lens with negative focal power, and the convex surface of the tenth lens faces the object space;

one convex surface of the ninth lens is cemented with the convex surface of the tenth lens.

7. The machine part profile measuring device of claim 1, further comprising: a plurality of space rings;

the space rings are respectively arranged between the front gluing lens group and the rear gluing lens group, and between the rear gluing lens group and the aperture diaphragm.

8. The machine part profile measuring device of claim 1, further comprising: a front fixed group lens barrel, a moving lens barrel and a rear fixed group lens barrel;

the front gluing lens group and the rear gluing lens group are fixed in the front fixing lens barrel;

the zooming group and the compensation group are in sliding connection with the moving lens barrel;

the rear fixing group is fixed in the rear fixing group lens barrel;

the front fixed group lens barrel is connected with the moving lens barrel through threads;

the movable lens cone and the rear fixed group lens cone are connected through threads.

9. The machine part profile measuring device of claim 1, further comprising: a first motor and a second motor;

the zooming group is fixed on the first motor through a pin; the first motor is used for driving the zoom group to make a specified motion;

the compensation group is fixed on the second motor through a pin; the second motor is used for driving the compensation group to make a specified movement.

Technical Field

The invention relates to the technical field of industrial measurement, in particular to a mechanical part contour measuring device.

Background

In China, machining enterprises such as cutters and gears are numerous, and the contourgraph is widely applied to production and machining. The traditional contourgraph mainly adopts a projection lens imaging mode to observe, the sensitivity of the detection instrument is not high, the lens matched with each contourgraph is a lens with a fixed magnification aiming at parts such as shafts, gears, cutters, splines and gaskets with different sizes, the field of view is limited, the magnification is not fixed under different object distances, and the comparison error is larger. Therefore, the existing equipment has the problem of large error.

Disclosure of Invention

The invention aims to provide a mechanical part contour measuring device, which solves the problem of larger error of the existing equipment.

In order to achieve the purpose, the invention provides the following scheme:

a machine part profile measuring device comprises: an object space telecentric system, an aperture diaphragm and an image space telecentric system;

the object space telecentric system comprises a front cemented lens group and a rear cemented lens group; the image space telecentric system comprises a zoom group, a compensation group and a rear fixed group;

the front gluing lens group, the rear gluing lens group, the aperture diaphragm, the zoom group, the compensation group and the rear fixing group are arranged in sequence from an object space to an image space;

and the exit pupil position of the object-side telecentric system is superposed with the entrance pupil position of the image-side telecentric system.

Optionally, the front cemented lens group includes a first lens and a second lens;

the first lens is a positive meniscus lens with negative focal power, and the convex surface of the first lens faces the object space;

the second lens is a biconvex lens with positive focal power;

the concave surface of the first lens is cemented with one convex surface of the second lens.

Optionally, the rear cemented lens group includes a third lens and a fourth lens;

the third lens is a positive meniscus lens with negative focal power, and the convex surface of the third lens faces the object space;

the fourth lens is a biconvex lens with positive focal power;

the concave surface of the third lens is cemented with one convex surface of the fourth lens.

Optionally, the variable power group includes a fifth lens and a sixth lens;

the fifth lens is a negative meniscus lens with positive focal power, and the concave surface of the fifth lens faces the object space;

the sixth lens is a negative meniscus lens with negative focal power, and the concave surface of the sixth lens faces the object space;

the convex surface of the fifth lens is glued with the concave surface of the sixth lens.

Optionally, the compensation group comprises a seventh lens and an eighth lens;

the seventh lens is a biconvex lens with positive focal power;

the eighth lens is a negative meniscus lens with negative focal power, and the concave surface of the eighth lens faces the object space;

one convex surface of the seventh lens is cemented with the concave surface of the eighth lens.

Optionally, the rear fixed group includes a ninth lens and a tenth lens;

the ninth lens is a positive meniscus lens with positive focal power, and the concave surface of the ninth lens faces the object space;

the tenth lens is a positive meniscus lens with negative focal power, and the convex surface of the tenth lens faces the object space;

one convex surface of the ninth lens is cemented with the convex surface of the tenth lens.

Optionally, the method further includes: a plurality of space rings;

the space rings are respectively arranged between the front gluing lens group and the rear gluing lens group, and between the rear gluing lens group and the aperture diaphragm.

Optionally, the method further includes: a front fixed group lens barrel, a moving lens barrel and a rear fixed group lens barrel;

the front gluing lens group and the rear gluing lens group are fixed in the front fixing lens barrel;

the zooming group and the compensation group are in sliding connection with the moving lens barrel;

the rear fixing group is fixed in the rear fixing group lens barrel;

the front fixed group lens barrel is connected with the moving lens barrel through threads;

the movable lens cone and the rear fixed group lens cone are connected through threads.

Optionally, the method further includes: a first motor and a second motor;

the zooming group is fixed on the first motor through a pin; the first motor is used for driving the zoom group to make a specified motion;

the compensation group is fixed on the second motor through a pin; the second motor is used for driving the compensation group to make a specified movement.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the invention provides a device for measuring the contour of a mechanical part. The device comprises an object space telecentric system and an image space telecentric system; object space telecentric system is preceding fixed group, and image space telecentric system includes: a zoom group, a compensation group and a post-fixation group. The device keeps the magnification of an object image space unchanged within a unit working distance by moving the zoom group and the compensation group and simultaneously linking the two groups. The object space telecentric system can eliminate errors caused by inaccurate focusing of the object space, and the image space telecentric system can eliminate measurement errors caused by inaccurate focusing of the image space. The image space telecentric effect is combined with the backlight source for irradiation, so that the contour images of the parts with different sizes (30-90mm) processed on line can be collected into a computer in real time through an image system and compared with a processing drawing, the detection and correction of the surface contour of the product can be visually and clearly completed, the processing efficiency of workers is comprehensively improved, and the measurement precision is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of a profile measuring apparatus for mechanical parts according to an embodiment of the present invention;

FIG. 2 is a light path diagram of a device for measuring the profile of a mechanical component according to an embodiment of the present invention;

FIG. 3 is a diagram of the structure of the variation of the zoom group and the compensation group according to the embodiment of the present invention;

FIG. 4 is a prescribed graph of a variable magnification group according to an embodiment of the present invention;

FIG. 5 is a graph illustrating the compensation group according to an embodiment of the present invention;

fig. 6 is a 3-fold zoom view of a mechanical component profile measuring apparatus according to an embodiment of the present invention.

Wherein, 1, a first lens; 2. a second lens; 3. a third lens; 4. a fourth lens; 5. an aperture diaphragm; 6. a fifth lens; 7. a sixth lens; 8. a seventh lens; 9. an eighth lens; 10. a ninth lens; 11. a tenth lens; 12. zooming group; 13. a compensation group; 14. a rear fixed group; 15. zooming group curve; 16. a compensation group curve; 17. an image space focus; 18. the image space height; 19. the height of the object space; 20. a front cemented lens group; 21. and a rear gluing mirror group.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

FIG. 1 is a schematic diagram of a profile measuring apparatus for mechanical parts according to an embodiment of the present invention; fig. 2 is a light path diagram of the mechanical component profile measuring apparatus according to the embodiment of the present invention.

Referring to fig. 1 and 2, the device for measuring the contour of a mechanical part includes: an object space telecentric system, an aperture diaphragm 5 and an image space telecentric system. The exit pupil position of the object-side telecentric system coincides with the entrance pupil position of the image-side telecentric system.

The object space telecentric system is a front fixed group and comprises a front cemented lens group 20 and a rear cemented lens group 21.

The front cemented lens group 20 is a positive power lens group, and the front cemented lens group 20 includes a first lens 1 and a second lens 2. The rear cemented lens group 21 is a positive power lens group, and the rear cemented lens group 21 includes a third lens 3 and a fourth lens 4.

The first lens 1 is a positive meniscus lens with negative focal power, and the convex surface of the first lens 1 faces the object space.

The second lens 2 is a biconvex lens of positive optical power.

The concave surface of the first lens 1 is cemented with one convex surface of the second lens 2.

The third lens 3 is a positive meniscus lens with negative focal power, and the convex surface of the third lens 3 faces the object space.

The fourth lens 4 is a biconvex lens of positive optical power.

The concave surface of the third lens 3 is cemented with one convex surface of the fourth lens 4.

The front and rear cemented lens groups 20 and 21 are double gauss in structure. Two groups of the cemented lenses of the front cemented lens group 20 and the rear cemented lens group 21 of the object space telecentric system adopt a symmetrical double-Gaussian refraction structure, which is beneficial to correcting chromatic aberration and improving the imaging quality.

The first lens 1 and the third lens 3 are made of crown glass with low dispersion coefficient, the abbe number of the first lens 1 is 70.13, the abbe number of the third lens 3 is 64.11, the dispersion coefficient of the first lens 1 and the dispersion coefficient of the third lens 3 are inversely proportional to the abbe number, and the smaller the dispersion coefficient is, the clearer the imaging is. The second lens 2 and the fourth lens 4 are made of flint glass with high refractive index, the refractive index of the second lens 2 is 1.80, and the refractive index of the fourth lens 4 is 1.78. The invention adopts crown glass with low dispersion coefficient, and the imaging is clearer when the dispersion coefficient is smaller. The object space telecentric system is sequentially provided with a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 along the optical axis direction, which is beneficial to correcting astigmatism and a field region, and the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all positive-negative focal power lenses, which is beneficial to correcting high-order aberration of an off-axis point.

The image space telecentric system comprises a variable magnification group 12, a compensation group 13 and a rear fixed group 14.

The variable power group 12 is a positive power lens group, and the variable power group 12 includes a fifth lens 6 and a sixth lens 7.

The fifth lens 6 is a negative meniscus lens with positive refractive power, and the concave surface of the fifth lens 6 faces the object space.

The sixth lens 7 is a negative meniscus lens with negative refractive power, and the concave surface of the sixth lens 7 faces the object.

The convex surface of the fifth lens 6 is cemented with the concave surface of the sixth lens 7.

The zoom group 12 is composed of a fifth lens 6 and a sixth lens 7 in sequence along the optical axis direction, which is beneficial to dispersing focal power burden and correcting spherical aberration.

The compensation group 13 is a positive power lens group, and the compensation group 13 includes a seventh lens 8 and an eighth lens 9.

The seventh lens 8 is a biconvex lens of positive optical power.

The eighth lens 9 is a negative meniscus lens with negative refractive power, and the concave surface of the eighth lens 9 faces the object.

One convex surface of the seventh lens 8 is cemented with the concave surface of the eighth lens 9.

The compensation group 13 is sequentially provided with a seventh lens 8 and an eighth lens 9 along the optical axis direction, which is beneficial to dispersing focal power burden and correcting spherical aberration.

The rear fixed group 14 is a positive power lens group, and the rear fixed group 14 includes a ninth lens 10 and a tenth lens 11.

The ninth lens 10 is a positive meniscus lens with positive power, and the concave surface of the ninth lens 10 faces the object.

The tenth lens 11 is a positive meniscus lens with negative refractive power, and the convex surface of the tenth lens 11 faces the object side.

One convex surface of the ninth lens 10 is cemented with the convex surface of the tenth lens 11. The rear fixed group 14 includes a ninth lens 10 and a tenth lens 11 in this order in the optical axis direction.

The distance between the eighth lens 9 and the ninth lens 10 is 1.5mm-10.5 mm.

The front cemented lens group 20, the rear cemented lens group 21, the aperture diaphragm 5, the zoom group 12, the compensation group 13 and the rear fixed group 14 are arranged in sequence from the object space to the image space. The surface of each lens group is spherical or plane. The surface types of the lenses adopted by the invention are all spherical surfaces or planes, and no aspheric surface is introduced, so that the processing and adjusting difficulty is reduced, and the cost is reduced.

The mechanical part profile measuring device further comprises: a plurality of cage rings.

The spacing rings are respectively arranged between the front gluing lens group 20 and the rear gluing lens group 21, and between the rear gluing lens group 21 and the aperture diaphragm 5. The method specifically comprises the following steps: the space ring is arranged between the second lens 2 and the third lens 3, and the distance between the second lens 2 and the third lens 3 is 20 +/-0.02 mm. The space ring is arranged between the fourth lens 4 and the aperture diaphragm 5, the space ring endoscope close to the fourth lens 4 is 18mm, the inner diameter of the aperture diaphragm 5 is 2mm, and the distance of the space ring is 68 mm.

The mechanical part profile measuring device further comprises: a front fixed group lens barrel, a moving lens barrel and a rear fixed group lens barrel. The length of the front fixed group lens barrel is 60mm, the length of the moving lens barrel is 59mm, and the distance from the rear fixed group lens barrel to the image side is 20 mm.

The front fixed group lens barrel and the movable lens barrel are connected through threads. The movable lens cone and the rear fixed group lens cone are connected through threads.

The front cemented lens group 20 and the rear cemented lens group 21 are fixed in the front fixed group barrel.

The zooming group 12 and the compensation group 13 are connected with the moving lens barrel in a sliding way. The zoom group 12 is located at one end of the moving lens barrel close to the object side, and the compensation group 13 is located at one end of the moving lens barrel close to the image side. The diameters of the fifth lens 6 and the sixth lens 7 of the variable power group 12, and the diameters of the seventh lens 8 and the eighth lens 9 of the compensation group 13 are each 10mm or half of the diameter of the moving barrel.

Fig. 4 is a prescribed graph of the variable magnification group according to the embodiment of the present invention, in which the horizontal axis of fig. 4 represents the focal length of the mechanical part profile measuring device, and the vertical axis represents the moving distance of the variable magnification group, and the unit is: millimeters (mm). FIG. 5 is a prescribed graph of the compensation group according to the embodiment of the present invention, in which the horizontal axis of FIG. 5 represents the focal length of the mechanical part profile measuring apparatus, and the vertical axis represents the moving distance of the compensation group, and the unit is: millimeters (mm). Referring to fig. 4 and 5, the inner wall of the moving lens barrel includes: a zoom group track and a compensation group track. The track of the zooming group track is that a zooming group curve 15 starts from one end of the moving lens barrel close to the object space, rotates a circle along the inner wall of the moving lens barrel, and ends in the middle of the moving lens barrel. The track of the compensation group track is that the compensation group curve 16 starts from one end of the moving lens barrel close to the image space, rotates a circle along the inner wall of the moving lens barrel, and ends in the middle of the moving lens barrel. A gap exists between one end of the zooming group track positioned in the middle of the moving lens cone and one end of the compensation group track positioned in the middle of the moving lens cone. When the zooming group 12 and the compensation group 13 respectively start to move from two ends of the moving lens barrel to the middle of the moving lens barrel, the focal length of the mechanical part contour measuring device is changed to 11-41 mm. The variable-magnification group 12 moves linearly in the moving lens barrel according to the variable-magnification group curve 15, and the moving amount is 1-25 mm. The compensation group 13 moves nonlinearly in the moving lens cone according to the compensation group curve 16, the moving amount is 1-34mm, and the zoom group 12 and the compensation group 13 move in the moving lens cone in a double-group linkage manner.

The zooming group 12 moves according to the zooming group curve 15, the second motor drives the compensation group 13 to move according to the compensation group curve 16, the zooming group 12 and the compensation group 13 are driven to move according to the specified curve of the figure 4 through the first motor and the second motor, the zooming group 12 is linked with the compensation group 13, the continuous zooming effect is achieved, and the requirements of online detection of parts with different sizes are met.

Fig. 3 is a structural diagram of a variation of the zoom group and the compensation group according to an embodiment of the present invention, referring to fig. 3, wherein (a) is a structural diagram in which the zoom group 12 and the compensation group 13 are respectively located at two end positions of the moving lens barrel, (b) is a structural diagram in which the zoom group 12 is located at a middle position of a track of the zoom group and the compensation group 13 is located at a middle position of a track of the compensation group, and (c) is a structural diagram in which the zoom group 12 and the compensation group 13 are respectively located at a middle position of the moving lens barrel. The zoom mechanism adopts a mechanical compensation zoom structure, and by adjusting the zoom group 12 and the compensation group 13 of the image space telecentric system, the zoom group 12 makes linear motion, and the compensation group 13 makes nonlinear motion, so that the zoom effect is achieved. The lateral arrows in (a) of fig. 3 indicate the adjustment ranges of the magnification-varying group 12 and the compensation group 13 in the moving lens barrel.

The rear fixed group 14 is fixed in the rear fixed group barrel.

In this embodiment, light rays exit from the object space, sequentially pass through the front cemented lens group 20, the rear cemented lens group 21, the aperture stop 5, the zoom group 12, the compensation group 13, and the rear fixed group 14, and then reach the image space focus 17.

The mechanical part profile measuring device further comprises: a first motor and a second motor.

The zooming group 12 is fixed on the first motor through a pin; the first motor is used for driving the zooming group 12 to make a specified motion, that is, the first motor drives the zooming group 12 to make a linear motion along the zooming group curve 15 on the zooming group track.

The compensation group 13 is fixed on the second motor through a pin; the second motor is used for driving the compensation group 13 to make a specified motion, that is, the second motor drives the compensation group 13 to make a nonlinear motion along the compensation group curve 16 on the compensation group track.

The following problems exist with the existing profiler systems on the market: 1. the projection system changes along with the object distance, the magnification ratio is not fixed, and the comparison error is larger; 2. for mechanical parts with different sizes, double telecentric systems with different multiplying powers need to be selected, so that the processing efficiency of workers is reduced; 3. the existing contourgraph is a large-view-field projection system, the view field is large, and the object distance is not fixed. Therefore, the existing contourgraph can not meet the requirements of real-time on-line detection of mechanical parts with different sizes and can not accurately measure mechanical parts such as gears and the like.

Fig. 6 is a 3-fold zoom diagram of the contour measuring apparatus for mechanical parts according to the embodiment of the present invention, referring to fig. 6, the zoom in the embodiment is the object-to-image ratio, the object-to-image ratio is the height of the object space divided by the height of the image space, and the height 18 of the image space in the embodiment is a fixed value. Fig. 6 (a) is a 1-time zoom view of the mechanical part profile measuring device, that is, when the zoom group 12 and the compensation group 13 are respectively located at two ends of the moving lens barrel, the object space height 19 is 30 mm; (b) the device is a 2-time zoom diagram of the mechanical part profile measuring device, namely the zoom group 12 is positioned in the middle of the zoom group track, and the object space height 19 is 60mm when the compensation group 13 is positioned in the middle of the compensation group track; (c) the object space height 19 is 90mm when the 3-time zoom image of the mechanical part contour measuring device, namely the zoom group 12 and the compensation group 13 are respectively positioned in the middle of the moving lens barrel. The mechanical part contour measuring device achieves 3-time zooming by adjusting the zooming group 12 and the compensation group 13 of the image space telecentric system.

Compared with the existing fixed-focus double telecentric system, the contour measuring device for mechanical parts adopts a mode of combining a fixed-focus object space telecentric system with a zooming image space telecentric system, utilizes the telecentric characteristic of the object space, drives a zoom group and a compensation group to move through a first motor and a second motor, the zoom group and the compensation group are linked, the magnification of the object space is kept unchanged within a unit working distance, because the object space telecentric system can eliminate errors caused by inaccurate focusing of the object space, and the image space telecentric system can eliminate measurement errors caused by inaccurate focusing of the image space, the comprehensive image space telecentric effect is realized, and the backlight source irradiation is matched, so that parts contour images with different sizes (30-90mm) processed on line are collected into a computer through an image system in real time, and compared with a processing drawing, the contour detection and correction of the surface of a product can be visually and clearly completed, the method can also be used for detecting the contour sizes of parts with different sizes on line.

The invention achieves the purpose of zooming by adjusting the zoom group and the compensation group, changes the object space view field, can accurately measure the size of the gear because the object space multiplying power of the double telecentric system is constant under the unit object distance, has no focusing error and reading error, further performs size comparison, compares and judges the deviation between the measured object and the given size, and detects whether the size of the processed object meets the processing error, namely the difference requirement between the actually processed object and the designed size.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.