Dome glass cover polishing method

Abstract

The invention discloses a dome glass cover polishing method. The dome glass cover polishing method is characterized by comprising the following steps of S1, cleaning and other pretreatment steps, S2, first polishing treatment, S3, second polishing treatment and S4, third polishing treatment. The large-size dome glass cover machined through the multi-time combined polishing method has the advantages of being small in edge effect, small in curved surface thickness error, high in machining precision and polishing efficiency, small in damage to glass and the like.

Description

Technical Field

[0001] The invention relates to the field of glass manufacturing, in particular to a polishing method for a large-size dome glass cover. Background Art

[0002] The space station is the base, permanent residence and transit station for human exploration of space. At the same time, the space station is of great significance to national defense security. As the window for external observation of the space station, the large-size dome glass has the characteristics of large size and large curved surface, which makes the processing of the dome glass extremely difficult and has extremely high requirements for its processing accuracy and surface quality.

[0003] At present, there is no successful polishing example of hemispherical glass with a diameter of more than 0.8m in China, and the traditional polishing method has problems such as low precision, high roughness, and glass surface damage when processing optical aspherical surfaces. At the same time, when the airbag polishing equipment is used alone to polish large-sized hemispherical glass, the efficiency is low, and the time and labor costs are high. At the same time, the polishing path of the airbag polishing equipment cannot solve problems such as glass edge effect. Summary of the invention

[0004] The present invention aims to overcome the deficiencies in the prior art and provides a polishing method for a large-size dome glass cover for a space station.

[0005] This application provides the following technical solutions: A dome glass cover polishing method, characterized in that it comprises the following steps: S1: a pre-treatment step such as cleaning, in which the inner and outer surfaces of the hemispherical dome glass are cleaned and pre-treated to remove stains and impurities on the glass surface; S2: The first polishing step is to polish the inner and outer surfaces of the dome glass by flame polishing. First, preheating is performed for 3-6 hours, and then flame polishing is performed for 10-24 hours. After completion, the inner and outer surfaces of the dome glass are cleaned again after natural cooling to remove impurities and residues on the surface of the dome glass after polishing. S3: a second polishing step, using a fixture to fix the dome glass in a curved surface polishing device to ensure that the dome glass does not shake during the grinding and polishing process, using diamond abrasives of different particle sizes to polish the inner and outer surfaces of the glass, and cleaning the inner and outer surfaces of the dome glass; S4: A third polishing step, in which polishing air bags with different radii, residence times, and polishing paths are used to polish the inner and outer surfaces of the dome glass in an air bag polishing device.

[0006] On the basis of the above technical solutions, there are also the following further technical solutions: The sphere diameter of the dome glass is 0.8m-1.2m, and the sphere thickness is 15-25mm.

[0007] The dome glass is fixed in the grinding and polishing equipment by vacuum adsorption.

[0008] The curved surface polishing equipment is a planetary grinding and polishing machine, the diamond grain size is 6-20 μm, and the polishing time is 24-72 hours.

[0009] The air bag polishing equipment is IRP1000 model of Zeeko Company of Britain.

[0010] In S4: 40mm, 80mm, and 160mm polishing airbags are used for convex surface polishing, and 20mm, 40mm, and 80mm polishing airbags are used for concave surface polishing. The airbag inflation pressure is 0.8-1.5 bar, and the airbag polishing time is 25-35 days.

[0011] The temperature of the flame polishing is 1650-2050°C.

[0012] Advantages of the invention: The present invention combines fire polishing with a planetary grinding and polishing machine to greatly reduce the polishing time. By first using fire polishing and then using a planetary grinding and polishing machine, the rough grinding and medium grinding processes are reduced. Since the diamond grain size is relatively large during rough grinding and medium grinding, there is a risk of scratching the glass surface and edge. Therefore, the present invention avoids the chance of damaging the glass during the rough polishing process. An algorithm is developed for the polishing process of large-size, hemispherical dome glass to optimize the residence time and polishing path of the polishing airbag, reduce the edge effect and improve the surface accuracy. DETAILED DESCRIPTION

[0013] A dome glass cover polishing method comprises the following steps: S1: cleaning and other pretreatment steps, cleaning and pretreatment of the inner and outer surfaces of the hemispherical dome glass to remove stains and impurities on the glass surface. The dome glass has a sphere diameter of 1m and a sphere thickness of 20mm.

[0014] S2: The first polishing step is to polish the inner and outer surfaces of the dome glass by flame polishing. First, the inner and outer surfaces of the dome glass are preheated for 4.5 hours so that the overall temperature of the dome glass reaches 1700 ± 5 degrees, and then flame polishing is performed for 21.5 hours. After the flame polishing is completed, the inner and outer surfaces of the dome glass are cleaned again after natural cooling to remove impurities and residues on the surface of the dome glass after polishing. Then proceed to the next step.

[0015] S3: The second polishing step, use a fixture to fix the dome glass in the curved surface polishing equipment (planetary grinding and polishing machine) to ensure that the dome glass does not shake during the grinding and polishing process. First, use diamond grains with a particle size of 16μm for fine grinding for 18-24h, and then use diamond grains with a particle size of 7μm for fine grinding for 24-48h to complete the polishing of the inner and outer surfaces of the glass, and clean the inner and outer surfaces of the dome glass. After drying, enter the next step.

[0016] S4: The third polishing step, the airbag polishing equipment is the IRP1000 model of Zeeko Company in the UK. 40mm, 80mm, and 160mm polishing airbags are used for convex polishing; 20mm, 40mm, and 80mm polishing airbags are used for concave polishing. The airbag inflation pressure during the entire polishing process is 0.8-1.5bar, and the airbag polishing time is 25-35 days. Polishing airbags of different diameters are selected according to the polishing position.

[0017] The IRP1000 airbag polishing equipment combines the large size and hemispherical shape of the dome glass, and uses the weighted spatial deconvolution algorithm based on the non-periodic matrix model to perform local adaptive control on deconvolution and smoothness, and uses the conjugate gradient iteration method to solve the discrete convolution equation to optimize the residence time and polishing path of the polishing airbag. Polishing airbags with different radii, residence times, and polishing paths are used to polish the inner and outer surfaces of the dome glass in the airbag polishing equipment.

[0018] Measure the glass accuracy RA. RA stands for rough accuracy in mechanical drawing. It means that the processing error of mechanical parts is allowed to have a certain range, but the range cannot exceed the tolerance value marked on the drawing. The RA level is divided into four levels from rough to ultra-precision: RA6, RA4, RA2, and RA1.

[0019] After completing step S2, measure the roughness of the dome glass to ensure that there are no burrs or impurities on the surface of the dome glass. After completing step S3, measure the roughness of the dome glass to ensure that the surface of the dome glass reaches the RA6 level. After completing step S4, measure the roughness of the dome glass to ensure that the surface of the dome glass reaches the RA2 level.

[0020] TTV is the abbreviation of Total Thickness Variation, which refers to the difference between the maximum and minimum thickness of the material within its diameter range. The TTV range needs to be ±0.5μm. The visible light transmittance of 380-780nm needs to be above 92%.

Claims

1. A method for polishing a dome glass cover, characterized in that: It includes the following steps: S1: cleaning and other pretreatment steps, cleaning and pretreatment of the inner and outer surfaces of the hemispherical dome glass to remove stains and impurities on the glass surface; S2: The first polishing step is to polish the inner and outer surfaces of the dome glass by flame polishing. First, preheating is performed for 3-6 hours, and then flame polishing is performed for 10-24 hours. After completion, the inner and outer surfaces of the dome glass are cleaned again after natural cooling to remove impurities and residues on the surface of the dome glass after polishing. S3: a second polishing step, using a fixture to fix the dome glass in a curved surface polishing device to ensure that the dome glass does not shake during the grinding and polishing process, using diamond abrasives of different particle sizes to polish the inner and outer surfaces of the glass, and cleaning the inner and outer surfaces of the dome glass; S4: A third polishing step, in which polishing air bags with different radii, residence times, and polishing paths are used to polish the inner and outer surfaces of the dome glass in an air bag polishing device.

2. A dome glass cover polishing method according to claim 1, characterized in that: The sphere diameter of the dome glass is 0.8m-1.2m, and the sphere thickness is 15-25mm.

3. The method for polishing a dome glass cover according to claim 1, characterized in that: The dome glass is fixed in the grinding and polishing equipment by vacuum adsorption.

4. The method for polishing a dome glass cover according to claim 1, characterized in that: The curved surface polishing equipment is a planetary grinding and polishing machine, the diamond grain size is 6-20 μm, and the polishing time is 24-72 hours.

5. The method for polishing a dome glass cover according to claim 1, characterized in that: The air bag polishing equipment is IRP1000 model of Zeeko Company of Britain.

6. The method for polishing a dome glass cover according to claim 1, characterized in that: In S4: 40mm, 80mm, and 160mm polishing airbags are used for convex surface polishing, and 20mm, 40mm, and 80mm polishing airbags are used for concave surface polishing. The airbag inflation pressure is 0.8-1.5 bar, and the airbag polishing time is 25-35 days.

7. The method for polishing a dome glass cover according to claim 1, characterized in that: The temperature of the flame polishing is 1650-2050°C.