Producing method of glass performing body for precise pressing and optical element
A press-forming and pre-formed body technology, which is applied in glass forming, glass manufacturing equipment, manufacturing tools, etc., can solve the problems of glass spreading and defects, and achieve high-quality results
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Embodiment 1、2
[0050] [Example 1, 2, comparative example]
[0051] A glass block of borosilicate-based optical glass having a refractive index [nd]: 1.839 and an Abbe number [vd]: 24.15 after melting / cooling / solidification was put into a platinum crucible heated to 1120°C and placed in the crucible After melting, it was clarified and stirred at 1250° C. to obtain a uniform molten glass. Next, the molten glass flowed out at a flow rate of 0.56 kg / hr from the temperature-controlled outflow conduit connected to the bottom of the crucible.
[0052] Such as figure 2 In this way, 12 lower molds are evenly arranged on the outer periphery of the circular molding table. In the following steps, the forming table was indexed and rotated every 9.5 seconds. As a cycle, each lower mold utilizes the indexing rotation of the forming table from figure 2 The shown first stop position is moved to the twelfth stop position, and one preform for precision press molding is produced in one cycle.
[0053] A co...
Embodiment 1
[0060] At the third stop position, a gas nozzle (6 mm in inner diameter) was installed so as to be located vertically above the upper surface of the glass block moved to this position. The distance between the front end of the gas nozzle and the upper end of the glass block is 2 mm to 3 mm, and the position of the gas nozzle is adjusted in advance so that the center of the gas nozzle coincides with the center of the glass block. The lower mold on which the pressed glass block is placed is moved to the third stop position by index rotation, and after 500 milliseconds have elapsed after the stop, the gas nozzle is supplied to the glass block at a flow rate of 10 L / min for 2000 msec. Nitrogen gas is ejected from the center of the upper surface ( figure 1 (d)). Thereafter, the same operation as in Comparative Example 1 was performed to obtain a preform having a similar shape.
Embodiment 2
[0062] The lower mold on which the pressed glass block is placed is moved to the third stop position by index rotation, and after the stop, from the moment when 500 milliseconds have elapsed, during 7000 milliseconds, the flow rate of 10 L / min from the gas nozzle to the Except that nitrogen gas was sprayed from the center of the upper surface of the glass block, the same operation as in Example 1 was carried out to obtain a preform having a similar shape.
[0063] exist image 3 The upper surface shape figure which measured the upper surface shape of the glass preform obtained in Example 1, 2 and the comparative example with the Mitutoyo contact type surface shape measuring instrument is shown. In addition, Table 1 below shows the results of measuring the shapes of the glass preforms obtained in Examples 1 to 3 and Comparative Example with the same surface shape measuring device.
[0064] [Table 1]
[0065]
[0066] Such as image 3 As shown in Table 1, after the pressin...
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