JPH01226746A - Glass lens formation mold - Google Patents

Abstract

PURPOSE:To obtain the lens of high accurate surface in the formation molds consisting of a pair of molds and a trunk mold by constituting the trunk mold of specified construction and making the thermal expansion quantity of the trunk mold larger than that of the parts of the lens and the formation molds. CONSTITUTION:In the formation molds consisting of a pair of molds 3, 4 and trunk molds, the trunk molds is constituted of a main trunk mold 6 and an auxiliary trunk mold 5 which are brought into contact with each other in the shifting direction of the formation molds, and the heat expansion quantity of the main trunk mold 6 and the auxiliary trunk mold 5 in the formation mold shifting direction is made to be larger than that of the thickness of the lens 7 and the received parts of the formation molds 3, 4 shifted in the main trunk mold 6 and in the auxiliary trunk mold 5, and the main trunk mold 6 is made to be positioned in the outer peripheral part of the lens material 8. The lens material 7 is supplied in this formation molds and heated to the transformable temp. and pressed to the end position by press heads 1, 2. The lens 8 is taken out after the cooling is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a glass lens mold for forming high-precision optical glass elements such as lenses and prisms used in optical equipment by an ultra-precision glass molding method.

BACKGROUND OF THE INVENTION In recent years, as a manufacturing method for high-precision optical lenses, especially aspherical glass lenses, many attempts have been made and are being realized by one-shot molding without using an optical polishing method and without a polishing process. One of the molding methods is to heat the glass material to a temperature at which it can be deformed, for example, to a temperature near its softening point, and then mold the glass material using means such as press molding. (for example,
(Japanese Unexamined Patent Publication No. 61-21927) This method requires a mold having a highly accurate surface shape and structure.

An example of a molding method using the conventional glass lens mold described above will be described below with reference to the drawings.

FIG. 5 is a cross-sectional view showing a lens formed by molding a spherical lens material using a conventional glass lens mold. 18.19 is a part of a press head having a heating and pressing mechanism, 20.21 is a pair of molds, 22 is a mold, 23
is a molded lens. Molding the lens material into a mold 20.
21, heated and press-molded. After the deformation is completed, the mold, the use mold, and the molded lens are gradually cooled down, and when the temperature reaches such a temperature that the lens can be taken out, the mold is opened and the lens is taken out.

Problems to be Solved by the Invention However, the above-mentioned molding method has a shape accuracy of 0.1.
In order to mold ultra-high precision lenses of micrometers or less, it is essential to maintain pressure on the lenses during the cooling process from after molding to the glass transition temperature. Therefore, in sizing molding where the lens thickness is regulated by the mold, the amount of thermal expansion of the mold in the sliding direction of the mold during the cooling process is accommodated in the lens thickness in the sliding direction of the mold and the mold. It must be greater than the amount of thermal expansion of the part. In other words, a mold with a coefficient of thermal expansion larger than that of the lens material must be used. However, if a mold with a large amount of shrinkage or thermal expansion is used, glass will enter the clearance between the mold and the mold, causing cracks and chips around the lens, or the lens will not come out from the mold. On the other hand, if a mold with a small amount of shrinkage, that is, a small amount of thermal expansion, is used, there is a problem that the desired ultra-high precision surface shape cannot be obtained.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a mold consisting of a main body mold and an auxiliary body mold, and the main body mold and the auxiliary body mold are connected in the sliding direction of the mold, and the molding The amount of thermal expansion of the main body mold and auxiliary body mold in the mold sliding direction is determined from the lens thickness in the mold sliding direction and the thermal expansion amount of the part of the mold that is slidably accommodated in the main body mold and auxiliary body mold. In this method, the lens material is made larger and the main barrel mold is located at the outer periphery of the lens material.

Effect of the present invention The main body mold and the auxiliary body mold connected in the sliding direction of the mold are slidably housed in the main body mold and the auxiliary body mold of the mold according to the lens thickness in the mold sliding direction by the above-mentioned means. The lens material shrinks more than the other parts, and pressure is constantly applied to the lens material even during the cooling process after molding. Therefore, a highly accurate lens surface shape can be obtained. Furthermore, since the main barrel mold, which shrinks less than the lens material, is disposed around the outer periphery of the lens material, the lens can be taken out smoothly without chipping or cracking of the lens edge.

EXAMPLE Hereinafter, a glass lens mold according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a state immediately before pressure molding of a lens material with a glass lens mold according to a first embodiment of the present invention. 1.2 is a part of a press head having a heating and pressing mechanism, 3.4 is a pair of molds, 5 is an auxiliary barrel mold, 6 is a main barrel mold, and 7 is a lens material. FIG. 2 is a sectional view showing the state immediately before the start of pressurized cooling in the first embodiment. 8
is a molded lens. Ll indicates the current length of the main body mold and auxiliary body mold in the sliding direction of the mold, and L2 represents the current length of the lens material and the portion of the mold that is slidably housed in the main body mold or auxiliary body mold. Show that. At this time, that is, immediately after the start of pressurized cooling, Ll and L2 are processed to have the same length, and the lens taken out after cooling has finished has a desired thickness. The coefficient of thermal expansion of the auxiliary body mold is larger than that of the lens material, and the material is larger than that of the main body mold and the mold, and the material is made so that Ll has a larger thermal expansion than L2. The processing consists of a trunk mold and an auxiliary trunk mold. Furthermore, the structure is such that a main barrel mold made of a material with a smaller coefficient of thermal expansion than the lens material is placed in a portion that contacts the outer circumference of the lens material.

Molding using the glass lens mold of the first embodiment of the present invention configured as described above will be explained with reference to FIGS. 1 and 2. Lens material 7 supplied as shown in Figure 1
is heated by some heating device (not shown) in the press head 12 to a temperature at which it can be deformed. When the temperature reaches a point where it can be deformed, pressure is applied using the press head 1 to push it out. Then, in the state shown in FIG. 2, the next pressurized cooling step is carried out. In this process, as mentioned above, the amount of thermal expansion of Ll is L2
Since Ll is larger than that of L2 during cooling, the contraction of Ll becomes larger than that of L2, and pressure is constantly applied to the lens material. When the cooling process is completed, the lens is taken out by some method not shown. Since the main barrel mold 6 is located on the outer periphery of the lens, as mentioned above, the lens material shrinks more than the top of the main barrel, so there is no chipping or cracking of the lens edge, and the lens can be easily taken out. I can do it. Since the lens material was constantly pressurized during the cooling process, the surface shape of the lens taken out after cooling was changed to the desired highly accurate surface shape.

Next, a second embodiment of the present invention will be described. FIG. 3 is a cross-sectional view showing a state immediately before the lens material is pressure-molded using a glass lens mold according to a second embodiment of the present invention. 9. IO is a part of the press head that has a heating and pressing mechanism; 1). 12 is a pair of molds, 13.14 is an auxiliary body mold,
15 is a main body type, and 16 is a lens material. FIG. 4 is a sectional view showing the state immediately after the start of pressurized cooling in the second embodiment. 17 indicates the length of the main barrel mold and the auxiliary barrel mold at that time, and L4 indicates the length of the lens material and the part of the mold that is slidably stored in the main barrel mold or the auxiliary barrel mold 13.14. show. The relationship between the lengths of L3 and L4 is similar to the relationship between L1 and L2 of the mold structure of the first embodiment. In other words, the lengths of L3 and L4 are the same immediately after the start of pressurized cooling, and the thickness of the sands taken out after the cooling is completed is processed so that it has a desired thickness. The coefficient of thermal expansion of the auxiliary body mold 13 and 14 is thicker than that of the lens material (and the material is larger than the coefficient of thermal expansion of the main body mold and the mold, and the amount of thermal expansion of L3 is greater than that of L4. The main barrel mold and the auxiliary barrel mold are constructed so that they are large in size.Furthermore, the main barrel mold 15 made of a material with a coefficient of thermal expansion smaller than that of the lens material is placed in contact with the outer periphery of the lens, and the auxiliary barrel mold It is configured to be connected between 13 and 14.

Molding using the mold of the second embodiment of the present invention constructed as described above will be described with reference to FIGS. 3 and 4. The lens material 16 supplied as shown in FIG. 3 is heated to a temperature at which it can be deformed by some heating device (not shown) of the press head 9.10. When the temperature reaches a point where it can be deformed, apply pressure to the press using the saw 9 and press it out. and the fourth
In the state shown in the figure, the process moves on to the next pressurized cooling process. In this process, since the structure is as described above, L3 is thicker than the contraction of L4 (and pressure is constantly applied to the lens material. Once cooling is completed, some kind of pressure (not shown) The lens is taken out by the method.The main barrel mold is located on the outer periphery of the lens, and as mentioned above, the lens material shrinks more than the main barrel mold, so there are no chips or cracks on the lens edge. Lenses can be taken out easily.

Since the lens material was constantly pressurized during the cooling process, the surface shape of the lens taken out after cooling was obtained with the desired high precision. After the cooling is completed, the surface shape of the lens taken out has the desired high precision.

Effects of the Invention As described above, in the glass lens mold of the present invention, the circular shape in the sliding direction of the mold is composed of a main body mold and an auxiliary body mold, and the amount of thermal expansion of the main body mold and auxiliary body mold is By making the thickness of the lens in the sliding direction of the mold larger than the amount of thermal expansion of the portion of the mold that is slidably accommodated in the main body mold or the auxiliary body mold, it is possible to mold a lens with a highly accurate surface shape. Further, by arranging the main body mold having a coefficient of thermal expansion smaller than that of the lens material at a position in contact with the outer circumference of the lens, there is no chipping or cracking of the lens edge, and the lens can be easily taken out.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the state immediately before pressure molding with a glass lens mold according to the first embodiment of the present invention, and Fig. 2 is a sectional view showing the state immediately before pressure molding with a glass lens mold according to the first embodiment of the present invention. 3 is a cross-sectional view showing the state immediately before the start of cooling; FIG. 3 is a cross-sectional view showing the state immediately before pressure molding with a glass lens mold according to the second embodiment of the present invention; FIG. 4 is the second embodiment of the present invention. FIG. 5 is a cross-sectional view showing the state of the glass lens mold in the example immediately before the start of pressure cooling, and FIG. 5 is a cross-sectional view showing the state of molding with the conventional glass lens mold. 1.2... Part of a press head having a heating and pressing mechanism, 3.4... A pair of molds, 5...
...Auxiliary body type, 6...Main body type, 7...
Lens material, 8... Molded lens, 9.1
0... Part of a press head having a heating and pressing mechanism, 1). 12...Pair of molds, 13.14
...Auxiliary body type, 15...Main body type, 16
...Lens material, 17.. Molded lens, 18.19.. Part of press head with heating and pressing mechanism, 20.21.. - A pair of molds, 22...circular shape, 23...molded lenses. Name of agent: Patent attorney Toshio Nakao and one other person Figure 8- Molded lens 15-
Main body type substitute

Claims (3)

[Claims] (1) In press molding, which consists of a pair of molds and a body die, and in which the lens thickness is regulated by the dimensions of the body in the sliding direction of the mold, the body mold is connected to a main body mold and an auxiliary body mold that are continuous in the sliding direction of the mold. Consisting of a body mold, the amount of thermal expansion of the main body mold and auxiliary body mold in the sliding direction of the mold is determined by the lens thickness in the mold sliding direction and the portion slidingly accommodated in the main body mold and auxiliary body mold of the mold. A glass lens mold characterized by a thermal expansion larger than that of the glass lens mold. (2) The main barrel mold is arranged so as to be in contact with the outer periphery of the lens, and the relationship between the thermal expansion coefficient α1 of the lens material, the thermal expansion coefficient α2 of the main barrel mold, and the thermal expansion coefficient α3 of the auxiliary barrel mold is α3>α1 ＞α
2. The glass lens mold according to claim 1, wherein: (3) The glass lens mold according to claim 1 or 2, further comprising one or more auxiliary barrel molds.