JPH0645463B2 - Optical component molding method and molding apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass lens forming apparatus and a glass lens forming method for forming a glass lens used in an optical instrument by a precision glass forming method.

2. Description of the Related Art In recent years, many attempts have been made to form an optical lens by one-shot molding without a polishing step. The most efficient method is to cast a glass material from a molten state into a mold and perform pressure molding, but it is difficult to control the shrinkage of the glass during cooling and is not suitable for precise lens molding. Therefore, it is a general method that the glass material is preliminarily processed into a predetermined shape, the glass material is supplied between the molds, and the glass material is heated and then press-molded. (For example,
JP-A-58-84134, JP-A-60-2008
As a construction method in which this molding method is improved to a method more suitable for mass production, a mold moving molding method has already been disclosed. (Unexamined-Japanese-Patent No. 62-292636) Hereinafter, the conventional molding method mentioned above is demonstrated, referring drawings.

FIG. 4 is a front view of a conventional moving die molding method, and FIG. 5 is a molding block.

In this method, the molding die is separated from the molding apparatus to form a molding block in which a pair of molding dies 1 and 2, a body mold 3 and a molding material 4 are integrated as shown in FIG. 5, and shown in FIG. First, the preheating stage S1 preheats to the molding temperature. Next, the molding block K is transferred to the molding stage S2 and pressure-molded to transfer the mold shape to the molding material. After that, the molding block K is sequentially transferred to the cooling stages S3, S4 to sufficiently cool and solidify the molding product, and then the molding product is taken out from the molding block K.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the method as described above, when the operation of supplying the material to the forming block or taking out the formed product from the forming block is performed at room temperature, if the heat capacity of the forming block increases, Since it takes a very long time to raise the temperature or lower the temperature from the molding temperature, the tacts of preheating, molding and cooling do not occur and the productivity is extremely deteriorated. Therefore, it is possible to improve productivity by dividing preheating and cooling into multiple stages and combining the tacts of preheating, molding, and cooling, but the molding machine becomes complicated and many molds are required. Had the problem of becoming.

The number of molds used can be reduced by taking out the molded product from the mold or raising the temperature of supplying the molding material, but the upper and lower molds 1 and 2 and the body mold 3 shown in FIG. Since the clearance between and is very small, around 10 μm, assembly and disassembly of the mold at high temperature has a problem that it is very difficult by the mold moving type molding method.

Means for Solving the Problems In order to solve the above-mentioned problems, the glass lens molding method of the present invention realizes an apparatus capable of disassembling and assembling a molding block even in a temperature atmosphere near the glass transition point. The means for taking out the molded product from the product or supplying the molding material at around the glass transition temperature at which the molded product solidifies is used.

Action According to the present invention, the temperature range for raising and lowering the temperature of the molding block can be greatly reduced by the above-mentioned means, as shown in FIG.
Therefore, the number of preheating and cooling stages can be small, and the structure of the molding machine can be simplified and the number of dies used can be greatly reduced.

Examples Hereinafter, one example of the glass lens molding method of the present invention will be described in detail with reference to the drawings.

1 (a) and 1 (b) show an outline of a molding apparatus according to the present invention.
1 (a) is an outline of a plan view seen from X ₂ -X _{2 in} FIG. 1 (b), and FIG. 1 (b) is a front view seen from X ₁ -X _{1 in} FIG. 1 (a). The outline of the figure is shown.

Reference numeral 1 is a molding block, 1a and 1b are upper and lower molds forming the molding block, 2 is a molded product taken out from the molding block, 3 is a preheated molding material, 4, 5 and 6 are preheating, molding and cooling heads. Reference numerals 7, 8 and 9 are preheating, molding and cooling stages corresponding to the head. Reference numeral 10 denotes a mold disassembling and assembling stage for supplying a new molding material 3 after taking out the molded product 2 from the molding block 1 which has been molded. Reference numeral 11 is a rail connecting between the stages, 12 is a belt for transferring the molding material 3 and the molding material 2, 13 is a suction arm for transferring the molding material 2 and the molding material 3, 14 is a molding portion, 1
Reference numeral 5 indicates a slow cooling section, and 16 indicates a mold input port.

Next, the operation of the present molding apparatus will be described.

The forming material 3 is placed on the belt 12 in advance and is sequentially transferred.
The slow cooling unit 15 has the highest temperature in the vicinity of the drawing and is set to the same temperature as the cooling stage. The temperature is set so that the temperature gradually decreases as it moves to the left, and the molding material 3 sent from the left is the belt 1.
2 is gradually preheated along with the transfer, and the molded product 2 is gradually cooled on the contrary.

After the molding material 3 is transferred onto the belt 12, an empty mold is inserted through the mold insertion port 16 and sequentially fed in the air. The feeding tact of the die and the feeding tact of the belt 12 are matched, and the die is disassembled when the first die is disassembled and transferred to the assembly stage 10. (The operations of disassembling the mold, assembling, taking out the molded product, and supplying the material will be described later.) After supplying the molding material 3 sucked by the suction arm 13 thereto, the mold is used as an assembling molding block, and the preheating stage 7 is reached. Transfer. The molding block 1 that has been preheated is transferred to the molding stage 8 and immediately subjected to pressure molding by the molding head 5. After the completion of molding, the molding block 1 is cooled to a temperature below the glass transition point at which the molded product solidifies on the cooling stage 9. The cooled molding block 1 is transferred to a mold disassembling / assembling stage kept at the same temperature as the cooling stage 9,
As described above, the mold is disassembled, the molded product 2 is sucked by the suction arm 13, taken out from the lower mold 1b, and transferred to the belt 12. The molded product 2 transferred to the belt 12 is sequentially stepwise fed according to the molding tact, and is cooled for a certain period of time by the cooling stage 9
After being kept at the same temperature as above, it is gradually cooled to room temperature.

On the other hand, the suction arm 13 transfers the molded product 2 onto the belt 12 and then sucks the molding material 3 fed stepwise and supplies it to the lower mold 1b. After that, the above operation is repeated.

Next, the disassembly / assembly operation of the mold will be described in detail with reference to FIGS. 2 (a) to (f).

2 (a) to (f) show the process of disassembling and assembling the mold.
B shown in FIG. 2 (a) is the pusher 2 from the cooling stage 9.
5, the molding blocks 21, 22 are upper and lower molds thereof, 23 is a barrel mold, and 24 is a molded product. The forming block B roughly positioned by the pusher 25 is
As shown in FIG. 3B, the guide punch 28 descends and the guide punch 28 is fitted by fitting the taper portion 28 a provided at the tip of the guide punch 28 and the taper portion 23 a provided on the body die 23.
Is accurately positioned so that the inner wall of the mold and the inner wall of the body mold 23 are coaxially aligned. Next, when the upper plunger 29 descends and comes into contact with the upper mold 21, the lower plunger 26 pushes up the molded product 24 together with the upper and lower molds 21 and 22, so that the end surface 22a of the lower mold 22 is moved as shown in FIG. 2 (c). End face 23b of the body mold 23
It will be stopped at the same position as or slightly higher. Body type 2 at this time
3 is fixed by a plunger 25. afterwards,
The suction ports 27 and 30 are vacuum-sucked at the same time, and the upper mold 21 and the lower mold 22 are vacuum-contacted to the upper plunger 29 and the lower plunger 26, respectively. Then, the upper die 21 is pulled up as the guide punch 28 and the upper plunger 29 are raised, and the upper and lower dies are divided. At this time, the lower die 22 is in vacuum contact with the lower plunger 26 and does not move with the rise of the upper die 21. After the upper die 21 has been pulled up to a certain size, a knock bar having a thickness approximately equal to the space between the upper and lower dies is inserted between the upper die 21 and the lower die 22 to form a molded product 24 (see FIG. Then, the molded product 24 is released from the upper and lower molds by pushing the side surface of the upper mold. Next, as shown in FIG. 2 (d), the suction arm 32 is moved between the upper and lower molds, the molded product 24 released from the mold is vacuum-sucked, and the arm is rotated as shown in FIG. 1 (a). The molded product 2 (24 in FIG. 2) is transferred onto the belt 12. Then, the molding material 3 (33 in FIG. 2) fed by the step feed of the belt 12 is adsorbed and supplied to the lower mold 1b (22 in FIG. 2). Next, as shown in FIG. 2E, the lower die 22 is pulled down together with the forming material 33 as the lower plunger 26 is lowered. After that, the guide punch 28 descends, and the inner wall of the barrel die 23 and the inner wall of the guide punch are aligned again by fitting the tapered portion 28a of the guide punch 28 and the tapered portion 23a of the barrel die.
Next, as the upper plunger 29 descends, the upper die 21 also descends, and after the upper die 21 contacts the molding material 33, the suction ports 27, 3
The vacuum suction from 0 is stopped, the guide punch 28 and the upper plunger 29 are pulled up, and the mold is assembled into the forming block B as shown in FIG. 2 (f). The molding block B is sent from the rear side to the front side by a pusher (not shown) to the rail 11 as shown in FIG.

The disassembling / assembling operation of the mold has been described above. The point of realizing the above operation is in disassembling and assembling the body die 23 and the upper and lower dies 21 and 22 which slide with a clearance of about 10 μm, and the guide punch 28 and the body die. A positioning mechanism provided in the die 23, selection of materials for matching the thermal expansion coefficients of the guide punch 28, the upper and lower plungers 26, 29 and the die, and a closed space by the guide punch 28, the upper plunger 29 and the upper die 21. Is formed and the gas in the space is sucked through the suction port 30 to obtain strong suction by simple vacuuming. In this embodiment, the guide punch 28 and the upper and lower plungers 26, 29 are made of a ceramic material having a thermal expansion coefficient close to that of the mold. It goes without saying that other materials may be used as long as the coefficient of thermal expansion is close to that of the mold.

Next, examples of actual molding using the molding apparatus according to the present invention will be described.

Using SF6 glass as a molding material, a biconvex lens having a diameter of 20 mm was molded. The preheating stage 7 shown in FIG.
0 ° C, molding stage 8 at 520 ° C, cooling stage 9 at 4 ° C
It was set to 00 ° C. (The glass transition temperature of SF6 is 420
℃) In addition, the slow cooling part is 40
The temperature of each zone was set so that the temperature was set to 0 ° C., the temperature was kept at 400 ° C. for 1 hour, and then gradually cooled. 4 molds are used,
The molding tact was molded in 2 minutes. When the performance of the molded lens is evaluated, the shape accuracy is λ / 2 (P-V value) and the internal strain is 2
It was 0 nm or less.

EFFECTS OF THE INVENTION As described above, by using the molding apparatus and the molding method according to the present invention, the temperature range for raising and lowering the temperature of the molding block can be significantly reduced. Therefore, the number of preheating and cooling stages can be minimized, the structure of the molding machine can be simplified, and the number of dies used can be greatly reduced.

[Brief description of drawings]

Figure 1 (a) is a plan view seen from X ₂ -X ₂ of the molding apparatus according to the present invention, FIG. 1 (b) is a front view seen from X ₁ -X ₁ of FIG. 1 (a), the 2 (a) to (f) are process drawings showing steps of the mold disassembly and assembly operation of the present invention, FIG. 3 is an explanatory view showing a molding profile, and FIGS. 4 and 5 are mold movements of a conventional example. It is a front view and a block diagram showing a formula forming method. 1 ... Molding block, 2 ... Molded product, 3 ... Molding material,
4, 5, 6 ... Preheating, molding, cooling heads, 7, 8, 9 ...
… Preheating, molding, cooling stage, 10 …… Die disassembly, assembly stage, 11 …… Rail, 12 …… Belt, 13 ……
Adsorption arm, 14 ... Molding part, 15 ... Slow cooling part, 16 ...
… Mold input port 21,22 …… Upper mold, Lower mold, 23 …… Cylinder mold, 24 …… Molded product, B …… Molding block, 25 …… Pusher, 29,26 …… Upper and lower plunger, 27 , 3
0 ... Suction port, 28 ... Guide punch.

Claims (6)

[Claims] 1. A forming block is prepared by supplying a forming material into a forming die having an upper die, a lower die and a body die having at least one optical surface, and transferring the forming block to a preheating stage to preheat to a forming temperature. And a step of transferring the preheated molding block to a molding stage to perform pressure molding, and transferring the molding block that has been molded to a cooling stage to change the temperature of the molded product from a temperature of a strain point or higher to a glass transition point or lower. And a step of cooling the molded block to a temperature between those temperatures and transferring the cooled molded block to a molded product take-out stage to take out the molded product from the molding block while maintaining the cooling completion temperature of the molded product. A method of molding an optical component, which comprises the step of supplying a molding material to a molding block and returning it to the preheating stage. 2. The method of molding an optical component according to claim 1, wherein a preheated material is supplied. 3. The method for molding an optical component according to claim 1, wherein each of the preheating, molding and cooling stages comprises a plurality of stages. 4. A molded product cooled in a cooling stage is taken out of a molding block while maintaining its cooling completion temperature,
2. The method for molding an optical component according to claim 1, wherein the temperature is kept at a temperature between the strain point and above and the glass transition point and below for a certain period of time in a slow cooling furnace, followed by slow cooling. 5. A preheating stage for raising a molding block, in which a molding material is supplied into a molding die having an upper die and a lower die having at least one or more optical surfaces, and a body die, to a molding temperature, and preheated molding. A stage for press-molding the block, a cooling stage for cooling the press-molded block to a temperature below the glass transition point, and a temperature between the temperature above the strain point and below the glass transition point Molding of optical parts, comprising: a molded product take-out and material supply stage; a mold multi-feeding mechanism for transferring a mold to each stage; and a slow cooling furnace for slowly cooling the molded product taken out from the molding block. apparatus. 6. As a mechanism for taking out a molded product from a molding block, a positioning mechanism for the molding block, a mechanism for holding and fixing the barrel die, and one end of a cylinder having the same inner diameter as the barrel die, on the outer peripheral portion of the barrel die. A mechanism for concentrically matching the inner wall surface of the barrel and the inner wall surface of the cylinder by fitting at least a part of
The upper and lower molds are slid in the body mold and the cylinder integrally by adhering to / adsorbing to the bottom surface of the upper and lower molds, which faces the optical surface, and
It was equipped with a pressing member that opens the upper and lower molds up and down, a mechanism that releases the molded product that is in close contact with either of the upper and lower molds from the mold, and a mechanism that supplies a new molding material after the molded product is taken out of the mold. The apparatus for molding an optical component according to claim 5, wherein