CN112536649A - Optical glass polishing method and device based on magnetic abrasive particle flow - Google Patents

Abstract

The invention discloses an optical glass polishing method and device based on magnetic abrasive grain flow. Magnetic abrasive grains, processing abrasive grains and dispersant are added to polymer colloid to prepare a polishing liquid with high concentration of magnetic abrasive grains; wherein, The mass fraction of magnetic abrasive particles in the polishing liquid is 75% to 95%, the mass fraction of polymer colloid is 10% to 20%, the mass fraction of processed abrasive particles is 1% to 5%, and the mass fraction of dispersant is 0.5% ~2%. At the same time, a device for realizing the above polishing method is disclosed. During the polishing process, the polishing device is used to control the relative movement between the optical glass parts and the polishing liquid, and a magnetic field generator is used to apply a magnetic field to the polishing liquid to adjust the grinding in the polishing liquid. The aggregation degree of the particles increases the friction between the parts and the abrasive particles, thereby realizing the micro-removal of the abrasive particles to the parts, and achieving the effect of high-efficiency polishing. The invention can realize high-efficiency and low-damage polishing of curved optical glass parts at low cost.

Description

Optical glass polishing method and device based on magnetic abrasive flow

technical field

The invention belongs to the polishing field of optical glass, and particularly relates to a method and a device for polishing optical glass based on magnetic abrasive particle flow.

Background technique

Optical glass has been widely used in aerospace, military equipment, nuclear power energy, medical and electronic equipment and other fields. Among them, the types of optical glass parts are mainly optical positioning lenses and optical path adjustment lenses. Different applications have different quality requirements on the surface of optical glass. For example, the optical components in space telescopes must have high mechanical strength and shape retention; the optical components of weapon aiming systems must have high accuracy and mobility; nuclear fusion high energy The optical components of the laser system must have high laser damage threshold; the optical components in various optical measuring instruments must have integrity and portability.

In order to meet the performance requirements of the above application fields, the working surface of optical glass parts must be ultra-smooth, with little/no surface damage, and strict requirements are placed on the polishing process. At present, for flat mirrors, traditional polishing methods can be used to produce very high-precision mirrors; for curved optical glass components, such as spherical mirrors and aspherical mirrors, mechanical small tool technology (CCOS), magnetic flow It is processed by computer-aided flexible polishing technology such as variable technology (MRF) and ion beam shaping technology (IBF). CCOS technology is based on numerical control system, which can use small tools to polish large-sized workpieces. The disadvantage is that the processing efficiency is low and there is edge effect. The processing medium of MRF is Bingham fluid with magnetic particles as the main component, which can realize material shearing during high-speed movement. The disadvantage of MRF is that the processing spot is small, which has certain restrictions on the size and curvature of the workpiece. In addition, the magnetorheological fluid has the defect of sedimentation, which limits its processing efficiency; IBF achieves surface material removal by bombarding the surface of the material with ion beams. The advantage is that there is no subsurface damage layer on the machined surface and no edge effect. The disadvantage is that the processing conditions are harsh (vacuum environment) and the processing efficiency is low. The common disadvantages of the above-mentioned polishing methods also include complicated process and high equipment cost.

The magnetic abrasive grain polishing methods disclosed in the application numbers 2006201055708 and 2015108115101 all use dry magnetic abrasive grains as the polishing medium, and the processing method is dry friction and wear. Such methods are prone to local energy accumulation on the machined surface, aggravating the surface damage of parts; In addition, since the processing medium is dry magnetic abrasive grain powder, even in the non-polarized state of the abrasive grains, it is difficult for the workpiece to easily enter the polishing medium due to the high degree of agglomeration of the abrasive grains.

To sum up, the existing polishing technologies are difficult to achieve efficient, high surface quality and low-cost polishing of optical glass parts. Therefore, it is necessary to develop a polishing method with high processing efficiency, low implementation cost, and guaranteed processing quality.

SUMMARY OF THE INVENTION

In order to overcome the defects of the prior art, the present invention combines the advantages of the magnetorheological fluid and the dry magnetic abrasive grain polishing method, and proposes a high-concentration magnetic abrasive grain fluid-based optical glass polishing method and device.

The technical scheme adopted by the present invention for solving its technical problem is:

An optical glass polishing method based on magnetic abrasive grain flow, adding magnetic abrasive grains, processing abrasive grains and a dispersant to a polymer colloid to prepare a polishing liquid with a high concentration of magnetic abrasive grains; wherein, the magnetic abrasive grains account for 5% of the polishing liquid The mass fraction is 75% to 95%, the mass fraction of the polymer colloid is 10% to 20%, the mass fraction of the processed abrasive particles is 1% to 5%, and the mass fraction of the dispersant is 0.5% to 2%.

During the polishing process, the optical glass parts and the polishing liquid move relative to each other, and a magnetic field generator is used to apply a magnetic field to the polishing liquid to adjust the concentration of abrasive particles in the polishing liquid and increase the friction between the parts and the abrasive particles. In this way, the micro-removal of abrasive particles to the parts is realized, and the effect of high-efficiency polishing is achieved.

Further, the magnetic abrasive particles are ferrite powder or hydroxy iron powder, and the particle size range is 0.05-3 μm; the polymer colloid is silica sol or aluminum sol; the processed abrasive particles are diamond, silicon carbide , alumina, cerium oxide, silicon oxide, zirconium oxide, titanium oxide, one or a mixture of several abrasive particles, the particle size range is 0.5 ~ 30μm, the type, particle size and concentration of the abrasive particles are based on the processing quality and efficiency of the polished workpiece Select.

Still further, in the polishing liquid, a dispersant may be added to prevent settling and agglomeration of magnetic abrasive grains and processing abrasive grains. The dispersant is one or more mixtures of oleic acid, polyethylene glycol, sodium hexametaphosphate, sodium pyrophosphate, and polyvinyl alcohol. Selection of material properties of the workpiece to be machined.

The invention further discloses a device for realizing the polishing method, comprising a polishing tank for holding polishing liquid, a magnetic field generator and a fixture for fixing parts, and the magnetic field generator is installed around the polishing tank , the fixture is located above the polishing groove.

Further, the polishing groove includes a roughing polishing groove and a finishing polishing groove, the processing abrasive grains of the polishing liquid in the roughing polishing groove are abrasive grains with larger hardness and particle size, and the polishing liquid in the finishing polishing groove is The processed abrasive grains are abrasive grains with smaller hardness and particle size. During the polishing process, the parts are first immersed in the roughing polishing groove for processing, and then immersed in the finishing polishing groove for processing.

Further, the magnetic field generator is an electromagnetic excitation coil with a spiral structure.

Still further, the clamp is connected with a driving mechanism for driving the clamp to rotate and move up, down, left, right and back.

The concept of the present invention is: to develop a magnetic abrasive particle flow polishing liquid containing processed abrasive particles to realize efficient and precise polishing of optical glass under the action of a magnetic field. Among them, the processed abrasive particles are hard abrasive particles or chemically active abrasive particles. The main function of the polymer colloid and dispersant is to maintain the stability of the abrasive particle distribution. The magnetic abrasive particles control the pressure between the processed abrasive particles and the parts under the action of an external magnetic field. The relative movement of the parts and the polishing fluid achieves the purpose of efficiently polishing optical glass parts.

Compared with the prior art, the beneficial effects of the invention are mainly as follows: it belongs to a fluid polishing method, which is suitable for processing curved surface parts; the processing abrasive particles are flexibly held by a magnetic field, which is beneficial to reduce the processing damage layer; the polishing process is divided into rough processing and processing, Different processing abrasive grains are used, which can effectively improve processing efficiency; the polishing liquid is easy to prepare, and the polishing device can be easily applied to CNC machine tools, which can significantly reduce processing costs.

Description of drawings

Fig. 1 is the structural representation of the magnetic abrasive grain flow polishing device of the present invention;

FIG. 2 is a schematic diagram of the flow state of abrasive grains when the polishing apparatus of the present invention is in a working state.

Detailed ways

The solution of the present invention will be further described below in conjunction with the accompanying drawings.

Referring to Figures 1 and 2, a method for polishing optical glass based on magnetic abrasive grain flow, adding magnetic abrasive grains 3 and processing abrasive grains 4 to polymer colloid 2 to improve polishing efficiency and reduce local temperature in the processing area, and then add dispersion It can improve the sedimentation stability of abrasive particles and prepare a polishing liquid with high concentration of magnetic abrasive particles; wherein, the mass fraction of magnetic abrasive particles in the polishing liquid is 75% to 95%, and the mass fraction of polymer colloid is 10% to 20%. , the mass fraction of the processed abrasive particles is 1% to 5%, and the mass fraction of the dispersant is 0.5% to 2%.

During the polishing process, the relative movement between the optical glass part 1 and the polishing liquid 5 is carried out, and the magnetic field generator 10 is used to apply a magnetic field to the polishing liquid 5 to adjust the aggregation degree of the abrasive particles in the polishing liquid and increase the distance between the parts and the abrasive particles. The friction force can be achieved to achieve the micro-removal of the abrasive particles to the parts, and achieve the effect of high-efficiency polishing.

Further, the magnetic abrasive particles are ferrite powder or hydroxy iron powder, and the particle size range is 0.05-3 μm; the polymer colloid is silica sol or aluminum sol; the processed abrasive particles are diamond, silicon carbide , alumina, cerium oxide, silicon oxide, zirconia, titanium oxide, one or a mixture of several abrasive grains, the particle size range is 0.5 ~ 30μm, the type, particle size and concentration of the abrasive grains are based on the processing quality and efficiency of the polished workpiece Select.

Still further, in the polishing liquid, a dispersant may be added to prevent settling and agglomeration of magnetic abrasive grains and processing abrasive grains. The dispersant is one or more mixtures of oleic acid, polyethylene glycol, sodium hexametaphosphate, sodium pyrophosphate, and polyvinyl alcohol. Selection of material properties of the workpiece to be machined.

An optical glass polishing device based on magnetic abrasive flow, comprising a polishing tank for holding polishing liquid 5, a magnetic field generator 10 and a fixture 6 for fixing parts, and the magnetic field generator 10 is installed in the polishing tank around the jig 6 is located above the polishing groove.

The polishing groove includes a rough machining polishing groove 9 and a finishing polishing groove 11. The processed abrasive grains in the rough machining polishing groove 9 are abrasive grains with larger hardness and particle size, and the polishing abrasive grains in the finishing polishing groove 11 are: For abrasive grains with smaller hardness and particle size, during the polishing process, the part 1 is first immersed in the roughing polishing groove 9 for processing, and then immersed in the finishing polishing groove 11 for processing.

The magnetic field generator 10 is an electromagnetic excitation coil with a helical structure, and the coil is spirally wound around the polishing groove. When the coil is energized, a magnetic field 13 approximately parallel to the main shaft 8 is generated in the polishing groove.

The optical glass polishing method based on the magnetic abrasive grain flow described in the present invention can realize the high-efficiency and low-cost polishing of the optical glass revolving body parts.

Add iron oxide powder and 1000# silicon carbide abrasive grains to the silica sol, and the dispersant is polyethylene glycol. After fully stirring, add the rough machining polishing tank 9; add the iron oxide powder and 1-3 μm cerium oxide abrasive grains to the silica sol , the dispersant is polyethylene glycol, after fully stirring, add the finishing polishing groove 11. The processing object is an aspherical mirror made of K9 glass. After the aspherical mirror 1 is fixed on the main shaft 8 by the clamp 6, the main shaft motor 7 is started to drive the main shaft 8 to rotate, and then the magnetic field transmitter 10 is energized to generate a magnetic field 13 from the bottom to the top in the polishing groove, so that the magnetic abrasive particles in the polishing liquid are gathered. On the upper layer of the polishing tank, a particle mass that wraps the processed abrasive particles is formed in the polymer colloid, and at the same time, the sedimentation of the abrasive particles in the polishing solution is effectively avoided, as shown in Figure 2. After the rough machining is completed, the magnetic field generator 10 is powered off, and the main shaft 8 is lifted; the worktable 12 moves the finishing polishing groove 11 under the main shaft 8, and then repeats the above rough machining process. In the finishing polishing tank, since the molecular formula of the silica sol is SiO ₂ ·nH ₂ O, a large amount of water molecules contained in it can undergo hydration reaction with the silicate glass network: Si-O-Si _(glass) +H ₂ O→2SiOH , a soft film is formed on the glass surface, which is convenient for the removal of abrasive particles; and cerium oxide is a chemically active abrasive particle, which can exchange ions with the glass surface to form Si-O-Ce bridge bonds, improve the friction between the abrasive particles and the surface of the parts, complete High-efficiency and low-damage polishing of optical glass.

The processed abrasive grains used in the present invention are hard abrasive grains or chemically active abrasive grains, and the processing medium is fluid, which is convenient for fitting the surfaces of curved parts. Under the action of the magnetic field, the polishing liquid forms a flexible abrasive tool on the surface of the processing object, and the surface material of the curved surface parts is flexibly removed through the relative movement of the parts and the polishing liquid.

The above are only specific embodiments of the present invention, and the technical features of the present invention are not limited thereto. Any simple changes or modifications made by those skilled in the art within the scope of the present invention are all covered by the present invention. within the scope of the patent.

Claims (7)

1. An optical glass polishing method based on magnetic abrasive particle flow is characterized in that: adding magnetic abrasive particles, processing abrasive particles and a dispersing agent into the polymer colloid to prepare a polishing solution with high-concentration magnetic abrasive particles; wherein, the magnetic abrasive particles account for 75-95% of the polishing solution by mass, the polymer colloid accounts for 10-20% by mass, the processing abrasive particles account for 1-5% by mass, and the dispersing agent accounts for 0.5-2% by mass.

In the polishing process, the optical glass part and the polishing solution move relatively, a magnetic field generator is adopted to apply a magnetic field to the polishing solution, the aggregation degree of abrasive particles in the polishing solution is adjusted, the friction force between the part and the abrasive particles is increased, the abrasive particles are removed slightly from the part, and the efficient polishing effect is achieved.

2. The method of claim 1, wherein the method comprises: the magnetic abrasive particles are ferrite powder or hydroxyl iron powder, and the particle size range is 0.05-3 mu m; the polymer colloid is silica sol or aluminum sol; the processing abrasive particles are one or a mixture of several of diamond, silicon carbide, aluminum oxide, cerium oxide, silicon oxide, zirconium oxide and titanium oxide, the particle size range is 0.5-30 mu m, and the types, the particle sizes and the concentrations of the abrasive particles are selected according to the processing quality and the processing efficiency of the polishing workpiece.

3. The method of claim 1, wherein the method comprises: in the polishing liquid, a dispersant may be added to prevent settling and agglomeration of the magnetic abrasive particles and the processing abrasive particles. The dispersing agent is one or a mixture of more of oleic acid, polyethylene glycol, sodium hexametaphosphate, sodium pyrophosphate and polyvinyl alcohol, and the type and concentration of the dispersing agent are selected according to the types of the processed abrasive particles and the polymer colloid and the material characteristics of the processed workpiece.

4. An optical glass polishing device based on magnetic abrasive particle flow is characterized in that: the polishing device comprises a polishing groove for containing polishing liquid, a magnetic field generator and a clamp for fixing parts, wherein the magnetic field generator is arranged around the polishing groove, and the clamp is positioned above the polishing groove.

5. An optical glass polishing device based on a magnetic abrasive flow according to claim 4, characterized in that: the polishing grooves comprise rough machining polishing grooves and finish machining polishing grooves, machining abrasive particles of polishing liquid in the rough machining polishing grooves are abrasive particles with larger hardness and granularity, and machining abrasive particles of polishing liquid in the finish machining polishing grooves are abrasive particles with smaller hardness and granularity.

6. An optical glass polishing device based on a magnetic abrasive flow according to claim 4, characterized in that: the magnetic field generator is an electromagnetic exciting coil with a spiral structure.

7. An optical glass polishing device based on a magnetic abrasive flow according to claim 4, characterized in that: the clamp is connected with a driving mechanism for driving the clamp to rotate and move up, down, left, right and back.

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