JPS6220136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a press lens mold, and particularly to a glass lens press mold with high thickness accuracy.

Traditionally, glass lenses are made by melting or softening glass, putting it into a mold, press-forming it into the approximate lens shape, then slowly cooling it to remove distortion, and then cold grinding and polishing it to achieve the required precision. Because it was manufactured by a method of applying it, it was expensive. Recently, the demand for inexpensive lenses has increased, and there is a demand for the development of a molding method that can be used only by press molding. In order to create a glass lens that can be assembled into a lens barrel without any grinding or polishing after molding, that is, that can be used only by press molding, it is necessary to Although it is necessary to improve the surface accuracy (surface roughness, sphericity, etc.), it is also necessary to precisely match the thickness of the glass lens to the required dimensions. For this purpose, it is necessary to obtain a glass gob with extremely high precision capacity using conventional molds. Moreover, conventional glass gobs have a capacity variation of approximately ±2.5%, and during press molding, the capacity variation of the glass gob was absorbed in the thickness direction. This will be explained using a diagram. FIG. 1 is a sectional view showing a state of a mold according to the prior art before press molding. In the figure, 1 is the upper mold, 2 is the lower mold, 3 is the body mold, 5 is the inner wall of the body mold 3, and 6
indicates a glass gob. FIG. 2 is a cross-sectional view showing the state during press molding, and the same parts are denoted by the same reference numerals (the same applies hereinafter). Reference numeral 9 denotes a press-molded glass lens, and in order to form the upper and lower surfaces of the glass lens 9, forming surfaces 10 and 11 are formed on the upper and lower molds, respectively. As is clear from Fig. 1 and Fig. 2, the upper mold 1 and the lower mold 2
Since the inner diameters of the outer mold and the inner wall 5 of the body mold 3 are almost the same, and the radial direction of the glass lens 9 is regulated, variations in the capacitance of the glass gob 6 directly result in variations in the thickness of the glass lens 9.

On the other hand, the wall thickness accuracy as a camera lens is ±0.03
Since it is required to be within mm, a gob with a capacitance accuracy of within ±0.5% is required depending on the lens aperture and shape. Obtaining gobs with such high precision is almost impossible with current feeders.

The present invention was made in view of the above-mentioned problems, and it is possible to reduce the thickness of a press-molded glass lens without significantly increasing the volumetric accuracy of the glass to be formed, such as a gob, placed in a mold. An object of the present invention is to provide a mold for a glass lens that can improve thickness accuracy.

The present invention has been made to achieve the above object, and includes an upper mold stop located at the periphery of a forming surface that forms the upper surface of a glass lens and formed on a plane perpendicular to this axis. an upper mold having an upper mold guide part located at the periphery of the upper mold stop part and inclined in a direction widening toward the opening side; and a lower mold having a forming surface forming a lower surface of the glass lens. a mold; an inner wall that is inscribed in the outer wall of the lower mold; and a mold that is located at the tip and comes into contact with the upper mold stop during press molding;
and a barrel mold stop formed on a plane perpendicular to the axis; a barrel guide located on the periphery of the barrel mold stop and having a shape corresponding to the upper mold guide; and the press. a body mold having a cavity formed by removing a portion of an inner wall facing the space formed by both forming surfaces of the upper and lower molds during molding, and stopping the upper mold during press molding. The glass lens mold is characterized in that the upper mold part and the body mold stop part are located on the same plane perpendicular to each axis of the upper mold and the body mold.

In the mold of the present invention, since the upper mold stop part and the body mold stop part are located on the same plane during press molding, the stopping position of the upper mold is determined with high precision, and the inner part of the body mold can be eliminated. The structure accommodates the excess capacity of the glass to be formed into the void, and the distance between the forming surfaces of the upper and lower molds, that is, the thickness of the glass lens to be press-molded, can be adjusted with high accuracy. is formed.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a sectional view of a mold according to an embodiment of the present invention at a press forming surface, and FIG. 4 shows a sectional view during press forming.

The upper mold 1' has a convex spherical forming surface 10 that forms the upper surface of the glass lens 9', and a flat surface perpendicular to the axial direction of the upper mold 2' at the periphery of the forming surface 10, as shown in the figure. The upper mold stop part 7 (in the figure, the bottom of the recess) formed in It has the following features: The lower mold 2' has a convex spherical forming surface 11 that forms the lower surface of the glass lens 9', and a rod 12 is connected to the center of the bottom surface of the lower mold 2'. The outer wall of the lower mold 2' is inscribed in the inner wall of the body mold 3', and the bottom surface of the lower mold 2' is in contact with the inner wall of the body mold 3'.
The rod 12 described above passes through a hole drilled in the center of the bottom. The body type 3' is
As shown in the figure, there is a gap 4 in which a portion of the inner wall 5 above the forming surface 11 of the lower die 2' (on the upper die 1' side) is cut out in an annular shape, and as shown in the figure, there is a gap 4 located at the tip thereof in the axial direction of the body die 3'. a barrel-shaped stop 8 formed on a plane perpendicular to the
The body mold guide part 14 (in the drawing, an inclined surface corresponding to the stop part 7 of the upper mold 1') is formed on the periphery of the body mold stop part 8.

The functions and effects of such a mold will be explained based on an example thereof. First, a glass gob 6 as a glass to be molded is placed on the forming surface 11 of the lower mold 2'. Next, the upper mold 1' is lowered. At this time, the upper mold guide part 1
3 descends while tracing the body mold guide part 14, so the central axis of the upper mold 1' and the central axis of the body mold are assembled within a predetermined tolerance, so that the central axis of the upper mold 1' The center axis of the lower mold 2' can be kept within a predetermined tolerance. Next, as shown in FIG. 4, the upper mold stop 7 comes into contact with the body mold stop 8, and a predetermined press pressure is applied to press-form the glass gob 6.
Here, press pressure is applied to the forming surface of the glass lens 9' and the barrel mold stop part 8, and the barrel mold guide part 14
does not participate in During this press molding, when the capacity of the glass gob 6 has a minimum variation, only a small amount flows into the cavity 4, and when it has a maximum variation, it flows almost completely into the cavity 4. , by bringing the upper mold and body mold stops 7 and 8 on the same plane into contact with each other, and while keeping the thickness of the formed surface (concave spherical surface) of the glass gob 6 constant, the excess capacity of the glass gob 6 is filled into the cavity. 4, a glass lens 9' having a desired thickness can be press-molded. Furthermore, since the side surface portion of the press-molded glass lens 9' is formed with an outer diameter dimension to which the inner diameter dimension of the inner wall 5 of the body mold 3' is transferred, when this outer diameter dimension is incorporated into the lens barrel, It can be used for.

After press molding, the upper mold 1' is opened, the rod 12 is pushed up, the lower mold 2' is moved upwards, and the glass lens on the lower mold 2' is brought out from the inside of the body mold 3'. Take out 9'.

According to the present invention, as described above, since the upper die stop part and the body die stop part are located on the same plane, both the upper die stop part and the body die stop part come into contact with each other during press molding. The excess capacity of the glass to be formed is accommodated in the cavity, and the axis of the upper mold is prevented from tilting.
The stopping position of the upper mold can be determined with high precision,
The distance between the forming surfaces of the upper and lower molds, that is, the thickness of the glass lens to be press-molded, can be formed with high precision.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the state before press forming in a conventional mold, Fig. 2 is a sectional view showing the state during press forming in the same conventional forming die, and Fig. 3
FIG. 4 is a sectional view showing the state of the mold according to the embodiment of the present invention before press forming, and FIG. 4 is a sectional view showing the state of the mold according to the embodiment during press forming. 1'...Upper mold, 2'...Lower mold, 3'...Body mold, 4...Gap, 5...Inner wall of barrel mold, 6...Glass cob, 7...Upper mold stop, 8...Body mold stop, 9... glass lens, 1
0...Upper mold forming surface, 11...Lower mold forming surface, 13...Upper mold guide part, 14...Body mold guide part.

Claims (1)

[Claims] 1 Forming surface 1 forming the upper surface of the glass lens 9'
An upper mold stop 7 is located on the periphery of 0 and formed on a plane perpendicular to this axis, and an upper mold stop 7 is located on the periphery of this upper mold stop 7 and is inclined in a direction that widens toward the opening side. an upper mold 1' having an upper mold guide portion 13, a lower mold 2' having a forming surface 11 forming the lower surface of the glass lens 9', and an inner wall 5 inscribed in the outer wall of the lower mold 2'. and a body mold stop part 8 which is located at the tip and comes into contact with the upper mold stop part 7 during press molding and is formed on a plane perpendicular to this axis, and a peripheral edge of this body mold stop part 8. A body mold guide part 14 located and having a shape corresponding to the upper mold guide part 13, and an inner wall 5 facing the space formed by both the forming surfaces of the upper and lower molds 1' and 2' during the press molding. and a body mold 3' having a cavity 4 formed by cutting out a portion, and the upper mold stop part 7 and the body mold stop part 8 are connected to the upper mold 1' during the press molding. and a mold for a glass lens, which are located on the same plane perpendicular to each axis of the body mold 3'.