Classification and characteristics of processing methods
In milling, turning and polishing as the representative, including the traditional generating milling and grinding and polishing; CNC milling, turning, precision grinding and polishing; computer controlled polishing. Especially for CNC polishing, the polishing media can be divided into small abrasives, stress plates, ion beams, plasma, magnetorheological and liquid jet polishing.
Its characteristics are relatively high efficiency, interworking with traditional optical processing, easy to be accepted, highly flexible, suitable for the development of samples and small batch production. But the consistency of the product is poor, and the demand for the operator is higher.
Mould forming method:
Glass hot pressing, optical plastic injection molding, heat deposition and curing forming. It is characterized by high efficiency, good consistency of finished products, low demand for operators, and suitable for mass production. However, the requirements of the mold are higher, the initial investment is large and the process flow is more complex.
Additional material method:
Vacuum coating and duplicating forming. The essence is to attach a layer of thin layer material to the degree of aspherical and refractive index on the basis of the closest sphere. The features of the workpiece have good consistency, low requirements for equipment and good flexibility. It is suitable for the production of small and medium size and reflective components. But the application is limited due to the matching of the additional layer with the base material.
Now let's take a look at some of the famous aspherical processing methods and equipment.
Super large grinder OAGM2500
Although the British Granfield university with Oxford, Cambridge compared to the not so famous, but as long as the CUPE Precision Engineering Research Institute, the industry respect. The Institute has developed ORGM2500 six axis CNC ultra precision grinder, Nanocenter250 and Nanocenter600 aspheric optical parts lathe and large ultra precision diamond mirror lathe.
OAGM2500 large CNC ultra precision grinding machine is a machine tool for processing large off-axis aspheric optical parts. The processing dimension is 2.5m * 2.5m * 0.61m. The hydrostatic bearing and friction drive mode are adopted. The position resolution and feedback of the laser interferometer is 2.5nm, the plane machining accuracy is up to 1 m, the surface roughness is 2 to 3nm, and the machining accuracy of off-axis aspheric mirror reaches 2.5 m. The ultra precision grinding machine is mainly used for 2.5 meters of ion beam polishing equipment of workpiece polishing of optical glass and other hard brittle materials with Kodak's modification of parts, can achieve very high precision workpiece. The machine bed is made of light steel welded structure and filled with S100 granite and polystyrene artificial granite in the middle. It ensures high stiffness, high stability and strong vibration attenuation ability.
The main body of the machine tool is Longmen type structure. The moving parts adopt precise guide rail and high-precision grating feedback. The 8 axis controller is applied to realize the combination of arbitrary axes and integrate the online profile measurement system. Process system open, multi track selection, compatibility, multi format data manipulation function parameters and optimization, to achieve the precision manufacturing of optical glass, ceramics, silicon carbide, quartz and other materials of optical elements, especially for high quality optical coaxial and off-axis aspheric element to develop adaptive processing model, achieve the polishing surface accuracy better than 1/50 (RMS, =632.8nm).
Magnetorheological polishing Q22-750P2
For optical glass, microcrystal, silicon carbide, quartz and other materials, better surface roughness and higher surface shape precision can be obtained. It is especially suitable for ultra precision machining of high quality optical coaxial and off-axis aspheric components.
Magnetic jet polishing
Magnetorheological jet polishing and magnetorheological jet technology is the combination of technology, magnetic rheological effect using low viscosity of magnetorheological fluid under magnetic field, the apparent viscosity increases to increase the stability of the jet surface, mixed with surface jet of magnetorheological fluid abrasive at the nozzle under the action of axial magnetic field the formation of collimated jet to harden at a certain distance, high-speed collision and shear action by abrasive to achieve the removal of materials, realize the polishing surface finishing in a controlled manner.
Let's take a look at the effect of the jet.
Polishing technique of stress disk
This is a very big on the polishing disk disk, stress evenly distributed on some columns, these columns by thread attached, these threads can relax the tension through the motor, which can control the deformation of the disk, and the workpiece is better fit, in order to achieve precision polishing. The disadvantage of the stress disk polishing is that it is too complicated to be controlled.
Ion beam polishing
Emitted by the ion source with certain energy and spatial distribution of ion bombardment of the surface of the workpiece, the workpiece surface after ion incident in a certain depth and workpiece atoms collide, the collision process, the incident ion will own energy transfer to the workpiece when the workpiece atoms, atomic energy gain is greater than that of its lattice binding energy. The workpiece atoms bound to off lattice motion, and the occurrence of collision cascade with other workpiece atoms, namely repeat the action when it is transferred to the next atomic energy is larger than the lattice binding energy, the next atom will leave the original position to start moving, if the atomic energy is not enough to overcome the lattice binding energy. The obtained energy will not be able to continue to pass, only to release the phonon form. In this process, energy is transferred between ions and atoms and atoms. When the energy on the surface of the workpiece is obtained along the normal direction of the mirror, the atom will fly off the surface of the workpiece when the component is larger than the binding energy and lattice binding energy of the material surface.
To say white is to remove one of the atoms on the surface of the material (a bit exaggerated).
The above is mainly about all kinds of polishing. It's just a working procedure in aspherical processing. The other materials are milling, rough grinding and fine grinding. Next is polishing, then coating. In addition to this, there are glass hot pressing, injection molding, heat settlement, copying and other techniques. The interested friends can look for information by themselves.
[disclaimer] this article is reproduced from the "world of light and electrical". The purpose of this article is to share information only, not to agree with the company. The content of the article is for reference only.
Taixing Hecheng Photoelectric Technology Co., Ltd. is a famous sapphire optical product (window, lens prism, light guide block). It has a complete set of advanced production equipment, and can undertake all kinds of high-precision optical products processing.
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Contact: Mr. Zhao