According to relative movement rule between lapping tool and workpiece in solid abrasive plane lapping this paper takes
a point on the workpiece as a differential unit to analyze force and moment acting on it, then we integratefor whole
workpiece, obtain the join moment acting on workpiece and get change relationship of join moment with workpiece
size and eccentricity. Because there is a transcendental function in integral equation, analytical result of join moment of
the lapping tool acting on the workpiece can not be got. By means of computer this paper gets digital results and draws a
three-dimensional figure of moment changing with workpiece size and eccentricity, which proposes a theoretical base for
selecting lapping parameters.
According to the existed method of positioning paraboloid surface workpiece for measuring its shape accuracy, this paper proposes a new method of positioning paraboloid surface workpiece with zero error sums. The key idea of new method is to consider whole workpiece surface comprehensively, which can appreciate whole workpiece surface reasonably, objectively and entirely. It is different from former measuring methods mainly considering several points with big errors. The new method is important for elements used in a optical system, since in optical system the main factors of affecting optical system characteristic are not only several points with big errors on optical element surface, but also the whole surface. It is favorable to improve workpiece surface shape accuracy and its optical characteristics. Its principle not only can be used in measuring paraboloid but also for measuring other aspheric surface.
The principle of solid abrasives lapping is that the abrasives are fixed and made into a special lapping tool; the workpiece is lapped in high speed lapping machine tool. It possesses many advantages compared with traditional low speed lapping with particulate abrasives, e.g. high machining efficiency, low machining cost, high and stable machining accuracy. So the highly efficient lapping method has been paid close attention to. This paper made a study on surface micro topography of different material by solid abrasive lapped at high speed. In experiments the lapping technique parameter is fixed, and different workpiece which are made by T10 steel, carbide, ceramic glass and alumina ceramics are lapped. The surface micro topography is measured by SEM, from the measuring result, it can be known that there is some shallow scribe on the surface of T10 steel, and the obvious plastic deformation can be observed. The SEM pictures show that there is some scribe on the surface of ceramics glass after lapped, with more magnification times many micro cracking and some plastic hump can be observed on the scribe. These scribes and humps are first cause of depressing surface quality, and these micro cracking can result in a lot of diffuse reflection on workpiece surface, it decreases the glossiness of mirror surface. On the surface of alumina ceramics there are a lot of defects, the size of such defect is more than the scribe of abrasive, it can be sure that the defect is not produced by lapping, so the material quality is an important effect fact to surface macro topography. On the surface of carbide there are a little of scribe and air cavity, and the scribe is very shallow; the defect of powder metallurgy martial is the primary reason.
This paper discusses a new lapping hyperboloid method, which combines high-speed lapping technology with solid abrasives and lapping tool bending method. In this method a bending moment is acted as a lapping tool with solid abrasives, which makes it bend and form a shape on its working surface, which is similar as the generating line of workpiece surface. In lapping, the lapping tool is coaxial with the axis of hyperboloid surface of the workpiece and the lapping tool rotates around it to lap. This kind tool is used in forming lapping on a high speed lapping machine.
This paper discusses a new lapping paraboloid method which combines high speed lapping technology with solid abrasives and lapping tool bending method. In this method a bending moment is acted on lapping tool with solid abrasives, which makes the tool bend and form a shape on its working surface which is same the as generant of workpiece shape. This kind of tool is used to form lap.
This paper discusses some problems about nanometer lapping photonics elements. The solid abrasives high speed lapping method and the theory of lapping tool wearing uniformly are used in machining photonics elements. It makes workpiece machined surface roughness reach to Ra0.88nm, flatness reach 19nm. That not only realizes nanometer machining, but also realizes machining at high efficiency and low cost.
A new optical expander is developed in this paper. It converts a beam of light from an Ar+ laser which has a diameter of 0.8 mm to a rectangular collimated light beam which has a height of 50~150mm and width of 1~10mm. This collimated light beam can be shifted 0~100 mm and convert 90° continually. The system is used in measuring fluid motion distribution. Its luminous energy utilization radio can reach 90%, much higher than 12.5% ratio of traditional expanding method.
This paper studies the effect of abrasives size on machined workpiece surface in solid abrasives lapping. From the results it can be seen that the value of roughness of the machined workpiece surface increases as the size of abrasives increases. Its principle is same as ultraprecision grinding and tradition lapping. But for same size abrasives, the results got in this paper is better than them in ultraprecision grinding and tradition lapping. In this paper, the roughness of machined workpiece surface can reach Ra2.83 nm, by using the abrasives which size is 3.5μm.
This paper discusses lapping a metal mirror with solid abrasives at high speed. In this method there are three procedures. First the workpiece is ground in a grinding machine, which makes the surface roughness of the workpiece reach about Ra1.6micrometers . Second the workpiece is lapped roughly on a lapping machine, which makes the surface roughness of the workpiece reach about 0.1micrometers . Last the workpiece is lapped finely, which makes the surface roughness of the workpiece reach about Ra1nm. Because solid abrasives are used, the machining efficiency is very high. Each lapping procedure time is only about one minute. A high speed, high efficiency and accuracy machining is realized.
This paper discusses a main unit of photoelectric automeasurement system for shape and position which is composed of slit scanning optical system with semiconductor laser and fine servo mechanical system. A single chip micro- computer, real-time data processor and other hardware are used to form a main controller to realize high sped, non- contact auto-measuring roundness, cylindricity, axiality and parallelism for revolving part C language is used to program for software. The computer is used for real-time data processing and controlling, displaying measuring result and printing output. Whole work of the system is done accurately and automatically with high speed. So it has good future in production.
After discussing the out-put characteristic of optical triangulation system in detail, some points of the relation between nonlinearity of triangulation and optical system parameters are concluded. These parameters include included angle, the magnification of imaging lens and objective distance of imaging lens. Then, to correct the nonlinearity a new method-asymmetrical gains method has been developed, the principle and the theoretic calculation result are given eventually.
This paper discusses a design of optical transfer system used in carbon-dioxide laser therapeutic machine. The design of this system is according to the requirement of the therapeutic machine. The therapeutic machine requires the movement of laser transfer system is similar to the movement of human beings arms, which possesses 7 rotating hinges. We use optical hinges, which is composed of 45 degree mirrors. Because the carbon-dioxide laser mode is not good, light beam diameter at focus and divergence angle dissemination are big, we use a collecting lens at the transfer system output part in order to make the light beam diameter at focus in 0.2 to approximately 0.3 mm. For whole system the focus off-axis error is less than 0.5 mm, the transfer power consumption is smaller than 10%. The system can move in three dimension space freely and satisfies the therapeutic machine requirement.
This paper discusses a light transfer system of therapeutic machine using carbon-dioxide laser. This system is based on imitating human being arm motion principle, consists of optical cardans mainly and can move in three-D space freely. Through it carbon-dioxide laser (which wavelength is 10.6 micrometer) is reflected, focused or diverged and transferred to the different therapeutic part of body to realize the purpose of cutting operation, gasification, cauterization and irradiation. This system includes an indicating system using He-Ne laser, by which carbon-dioxide laser can arrive therapeutic part accurately. This system possesses some advantages e.g. an accurate transfer, large moving range, small power consumption, high power density and easy operation. At present the occupancy in home market of this kind laser transfer system products is over 95%. Some products have been exported to other countries.
This paper introduces the properties of BaF2 crystal material. According to these properties material selecting is discussed including initial separation and finish separation, e.g. checking crystal lithogenesis, intercalation, cloud, uniformity and stress and so on. Determine methods are given also. The BaF2 machining technology is studied. Comparing different cutting methods we select the cutting method with steel saw blade. For the soft and brittle properties of BaF2, we probe the rough lapping finish lapping and polishing and for different procedure give selecting principle for abrasive, spindle rotating speed, machining allowance, size tolerance, and iris and relative data. Through machining experiments we find that the workpieces machined adopting the technology proposed in this paper can meet the drawing requirement e.g. N equals 1, (Delta) N equals 0.1, center thickness d equals 4 +/- 0.10 surface roughness Ra 0.008 micrometers (P equals III). The paper also points out some problems should be attended to in machining BaF2 crystal.
Lapping is an important method in optical element machining. In lapping a workpiece is pressed on the lapping to by a press head through a press disc, which produces a friction force between the lapping tool and the workpiece and forms lapping. The friction moment between the press head and press disc resists workpiece rotating and affects machining accuracy. This paper in theory discusses this moment in detail. According to the press head and press disc elastic deformation produced under action of pressure, the contact stress distribution between them can be got. By means of this stress distribution function, the infinitesimal moment can be got. Through integrating an analytic result of resultant moment can be got too. From this result we can easily find that the factors affecting the moment and affecting role, which provides a theoretical base for increasing lapping accuracy, reducing the moment and a base for researching relative motion in floating lapping deeply.
This paper studies the LiNbO3 crystal rohomboprism machining problem, introduces how to select material including initial separation and finish separation and determine optical axis, proposes a method to determine material uniformity according to graph of interference fringes and discussed the technology problems of rough lapping, finish lapping and polishing and some problems should be attended to e.g. temperature, spindle rotating speed, abrasives, hanging method and iris controlling and so on. Some methods for measuring rhomboprism and formula for calculating deviation angle are given. The workpiece machined by the machining technology proposed in this paper surface flatness is 0.1 micrometers , roughness is Ra 0.008 micrometers (P equals III), angle error is 1', parallelism error is 15', which can meet the drawing requirements.
This paper discusses the improvement of high speed flat lapping machine with grating measuring length system and an MCS-51 single chip computer, which makes the machine possesses the ability of measuring and controlling for lapping quantity and improves the machine property and machining accuracy. The original size and need size of workpiece are known. The difference between of them is lapping quantity (before lapping) is input into the computer. In lapping the grating measuring length system on- line measures the lapping quantity, the computer compares the measured lapping quantity with l, makes a decision according to the comparing result and decides whether to stop the machine. When the measured lapping quantity equals l, it is expressed that the workpiece is lapped to required size, the computer makes the machine stop, which assures the workpiece size accuracy automatically, improves machine automaticity and makes up the disadvantages that an ordinary flat lapping machine can not control the lapping size effectively. Through experiments it is found that measuring and controlling accuracy of improved lapping machine is +/- 2 micrometers .
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.