The spherical surface of the lens is constructed by single processing of the direct diamond
plate tool without carrying out CG processing of the press glass material.At the same time,
roughness of the spherical surface R and the centre thickness is stabilized and then
processing is carried out. Implementation is carried out by the invention of the company
“Completely CG less option (applied for patent)” from NC Grinding Machine PM series (Our
Company, Patent No.3981326)
NC Grinding Machine
Fully Automatic NC Grinding Machine
When this method is used, CG process is not required as was the case in the past.Grinding is carried out directly by the diamond plate.
Grinding can be carried out even if there is unevenness, punch mark or flash of the glass material. Scraps, burr etc are not generated.
Usually, grinding is done in a single burst with thickness of 0.5mm-0.7mm, however, since there are variations in glass material, the diamond plate particle size, the bonding material, and the grinding time varies from 40-70 seconds on average.
The diamond plate wear volume is considered as 0.2µm-0.5µm.
The diamond plates to be used can be selected from #400～ #8000～1200 which are currently being used.
However, diamond plate used during single sphere processing is used in core mechanism ball polishing machine.
During grinding, the scraps for plate, deformation, and abnormal lesions are not found. The variations during processing are maintained within ±1µm.
The checking and experimental proof is obtained by the continuous grinding test exceeding approximately 5,000 surfaces.
The graph shows surface roughness for the grinding surface. Cutting depth for #800 plate is 4µm/MAX.
No lesions or marks are seen on the grinding surface deeper than these. No scratches or clogging for the slip portion are observed.
-Refer to Appendix Data 1-
Center thickness is given below.
It can be controlled automatically within ±10µm (width 20µm).
-Refer to Appendix Data 2-
As mentioned above, it will surpass all the common knowledge about glass lens processing used in the past. This method ‘CG less option’ (Applied for Patent) is developed using experimental proof of actual test carried out over a period of past 6 months. In the appendix data, revision of centre thickness (oscillation height, R revision) is activated and implemented to 5µm for grinding work of 20 surfaces. According to this, 5µm/20 surfaces =0.25µm. Diamond plate wear volume is 0.25 for 1 processed surface. Diamond plate gets damaged just a little. Hence, grinding surface is made stable and finishing is done at fixed R.
According to this method, material, intermediate work expenses can be reduced significantly by carrying out measurement of lens (shortening of process line, resulting in significant shortening of production lead time); hence, overall significant cost cutting is possible due to this method.
Further, even if the quality aspect is considered in addition to costing, the standards for centre thickness ±20-30µm can be considered as general standards with ±10µm.
Further, ±5µm can be controlled sufficiently.
The above result is derived considering the grinding process as the focal point. This equipment and option can also be used for application of polishing process. Advanced results for polishing process are anticipated. Currently, the lens will be available as per the convenience of procurement of glass material; the process validation will be done for 10φ-80φ uneven 5R-plane surface and glass material wear in the range 70-250. Moreover,this technology can be adapted to wide range of glass materials after reviewing the diamond particle size, bond etc. and can be applied to technical know-how of each company. The technology will make further progress in the future and affect the way the lens processing works. Currently, the company is carrying out inspection for the status of the normal process. Kindly contact if you are interested.