JPH04154636A - Apparatus for forming glass lens - Google Patents

Abstract

PURPOSE:To enable the centering of the forming apparatus in high accuracy by forming a recess directing in radial direction near the circumference on an end face of opposite end faces of a pair of upper and lower molds and forming a protrusion on the other end face. CONSTITUTION:A bracket 9 is lifted along a stationary shaft 2 to open a molding chamber 11, a lens raw material 30 is placed on a die piece 53 of the lower mold assembly 5, the bracket 9 is lowered, the chamber 11 is closed with a quartz tube 10, an inert gas is supplied to the chamber 11 through gas-supplying lines 17,18 and the raw material 30 is heated with an infrared lamp 14 through the upper and lower mold assemblies 4,5. The mold-clamping apparatus 6 is actuated to lift the movable shaft 7 and the material 30 is press-formed by pressing the lower mold assembly 5 against the upper mold assembly 4 while engaging three or more protrusions 44 and three or more recesses 54 directing from the mold center in radial direction and formed near the outer circumference of the end faces 52a, 42a of the movable die 52 and the stationary die 42.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an apparatus for press-molding a glass lens (including other glass optical elements such as a prism) using a pair of upper and lower molds. , especially regarding improving the precision of glass lenses.

(Prior Art) The accuracy of a glass lens press-molded by a pair of upper and lower molds is directly influenced by the accuracy of the molds themselves as well as the centering accuracy of the pair of upper and lower molds. Traditionally, centering of molds was done using Japanese Patent Laid-Open No. 47-
A method in which multiple pins and holes were provided on opposing end surfaces of a mold, as shown in Publication No. 11277, was generally adopted, but the method using pins and holes has a limit, especially in the machining accuracy of the holes themselves. At the same time, it is difficult to process the estimated distance of pins and holes with high precision, so it is unsuitable for micron order centering.
As shown in Publication No. 35, the molds are centered and mounted on their mounting shafts with high precision using a special jig, eliminating the need for centering between the molds using a bottle and a hole. The following have been proposed.

(Problems to be Solved by the Invention) The method disclosed in JP-A-63-147835 enables highly accurate centering during installation, but when actually press-molding, the mold is heated to a high temperature and the mold is not installed. Since the shaft is cooled through a heat insulating material, misalignment may occur due to distortion or thermal deformation due to differences in thermal expansion. Therefore, in order to perform centering with higher accuracy, it is also necessary to provide a highly accurate centering means between the pair of upper and lower molds to perform direct centering between the molds.

An object of the present invention is to provide a glass lens molding apparatus that can directly center a pair of upper and lower molds with high precision.

[Structure of the invention]

(Means for Solving the Problems) The present invention to achieve the above object is to provide three or more force points near the outer periphery on the -1 end face of the end face of the mold, and open the outer periphery side and the end face Ill. It has a concave portion extending substantially radially from the center of the mold, and a convex portion provided on the other end surface corresponding to each of these concave portions, and the concave and convex portion has a concave portion that extends in a direction substantially radial from the center of the mold. The side surface is formed to have a predetermined fitting accuracy.0 Note that the side surface of the uneven portion preferably extends in a radial direction from the center of the mold, and furthermore, Preferably, the joint portion is formed to be slightly movable in the radial direction with respect to the center of the mold.

(Function) The above-mentioned uneven parts can be sufficiently machined on the micron order using high-precision machine tools, and since they are provided near the outer periphery of the mold and the distance between each uneven part is large, it is relatively easy to machine. Highly accurate centering is performed at the same time, and positioning in the rotational direction relative to the center of the mold is also performed at the same time, making it possible to handle glass lenses that require alignment in the rotational direction. In addition, if the side surfaces of the uneven portion extend in the radial direction from the center of the mold, misalignment will not occur even if there is a difference in thermal expansion between the upper and lower molds, and the joint between the mold and the shaft will not occur. If it is formed so that it can move slightly in the radial direction with respect to the center, mold closing and centering can be performed in a more normal state without being affected by the difference in thermal expansion between the mold and the shaft or by the thermal deformation of the shaft. It will be done.

(Embodiments) Examples of the present invention will be described below with reference to all of FIGS. 1 to 3. In FIG. 1, l is a frame;
A fixed shaft 2 extends downward from the top, and an upper die assembly 4, which will be described later, is attached to the lower end of the fixed shaft 2 via a heat insulator @3 made of Si3N4, quartz glass, or the like. A mold clamping device 6 is provided at the bottom of the frame 1, and a moving shaft 7, which is moved up and down by the device 6, extends upward facing the fixed shaft 2. A lower die assembly 5, which will be described later, is attached to the upper end of the moving shaft 7 via a heat insulating shaft 8.

A bracket 9 is movably engaged with the fixed shaft 2 and is moved up and down by a drive device (not shown). A quartz tube 10 surrounding the pair of mold assemblies 4 and 5 is attached to the bracket 9. The lower end of the quartz tube 10 is in airtight contact with the intermediate plate (IA) through which the moving shaft 7 passes, and the mold assembly 4. A molding chamber 11 that is cut off from the atmosphere is formed around -. An outer cylinder 12 surrounding a quartz tube 10 is attached to the bracket 9, and a lamp unit 13 is provided on the outer cylinder 12. cormorant/
Puuni 7) It has a 13H1 infrared lamp 14 and a reflection mirror 15, and it heats the mold assemblies 4 and 5, and also completely cools the reflection mirror 15 etc. with a water-cooled vibrator 16.The fixed axis 2 moves @7. And the bracket 9 has a molding chamber l.
Gas supply passages 17, 18 and 19 are provided for creating an inert gas atmosphere inside the mold assembly 4.5 and for cooling the mold assembly 4.5, and the intermediate plate (IAK) is provided with an exhaust port 20. Note that 21 is a thermocouple for detecting the temperature of the lower die assembly 5.

Fig. 2 shows an enlarged view of the upper and lower die assemblies 4, 5, the heat insulating shafts 3, 8, and the fixed and moving axes 2.7. Consisting of a fixed die 42 and a die piece 43 made of SiC, the lower die assembly 5, like the upper die assembly 4, includes a die plate 51 and a movable die 52 made of tungsten alloy, and a die piece 43 made of SiC.
It consists of a die piece 53 manufactured by Manufacturer.

End IJrJ52 of the movable die 52 facing the fixed die 42
As shown in FIG. 3, recesses 54 are provided at four equal intervals on the circumference near the outer periphery. As shown in FIGS. 2 and 3, these recesses 54 are groove-shaped, with the outer peripheral side and the end surface 52a side of the movable die 52 open, and extending substantially radially from the mold center 0. On the other hand, the end surface 42 of the fixed die 42
A is provided with a convex portion corresponding to the concave portion 54.

These concave portions 54 and convex portions 44 are machined to have extremely high hanging angle accuracy, and are machined to have particularly high dimensional accuracy of the width of the side surface 54a of the concave portion 54 and the corresponding side surface 44a of the convex portion 44, Both side surfaces 54a t 44a are formed to be removable from each other with a gap on the order of microns. Note that these side surfaces 54a and 44a are
In the mold closed state where the end surfaces 52a, 42a of 2 and 42 are in close contact with each other, the end surfaces 52a and 42 may be tapered surfaces that engage with a predetermined gap t on the order of microns or less than 1. The other surfaces of the concave portion 54 and the convex portion 44 except for the side surfaces 54a and 44a are formed to face each other with a relatively large gap.

The die pieces 43 and 53 are fixed or movable dies 42°5
The stepped holes 42b, 52b, and 52b provided in the center of 20 are inserted and supported, but these stepped holes 42b, 52b
In this case, the above-mentioned uneven portions 54 and 44 are formed first, and then both dies 4 are assembled.
2, 52 are combined, it is preferable to perform so-called matching processing to align the centers of both stepped holes 42b, 52b. 45 and 55 are integrally assembled to the Goui plates 41 and 51, respectively.

The die plates 41, 51 are attached to the insulating shafts 3, 8 by stepped poles 22, 23, with low friction bodies 46, 56i interposed, preferably graphite films or the like. The stepped poles 22 and 23 relatively loosely tighten the heat insulating shafts 3 and 8 and the guide plates 41 and 51 to allow at least a slight relative movement between them in the radial direction from the mold center O. . The insulation shaft 3°8 is bolt 24
, 25 are clamped to the fixed or movable shaft 2.7, respectively.

Next, the operation of the non-equipment will be explained. The bracket 9 is raised along the fixed shaft 2 to open the molding chamber 17, and the lens material 30 is carried onto the die piece 53 of the lower mold assembly 5, which is at the mold opening position below the position shown in FIG. Next, the bracket 9 is lowered, the molding chamber 11 is closed with the quartz tube 10, and inert gas is supplied from the gas supply channels 17 and 18.19 to create an inert gas atmosphere in the molding chamber 1117.
The upper and lower mold assemblies 4 and 5 are heated by the infrared lamp 14, thereby heating the lens material I. The temperature detection thermocouple 21 detects that the temperature of the lower mold assembly 5 has reached a predetermined molding temperature, and the mold clamping device 6 is activated to raise the moving shaft 7, moving the lower mold assembly 5 to the upper mold assembly 4. The lens material 30 is press-molded.

At this time, for example, both dies 42 and 52 and the dive L/
- By selecting a tungsten alloy that has a thermal expansion coefficient equal to the 5iCO thermal expansion coefficient of 4.5 x 10' that forms the die pieces 43 and 53, the mold assembly 4.5 However, if the insulation shafts 3 and 8 are made of quartz glass, the coefficient of thermal expansion of quartz glass is as small as 0.5 Distortion and misalignment occur due to the difference in thermal expansion between the mold assemblies 4 and 5. Although the fixed and movable shafts 2.7 are kept at a relatively low temperature, they may undergo thermal deformation under the influence of the above-mentioned navigation, which also causes misalignment.

Therefore, when both mold assemblies 4 and 5 are clamped, the end faces 52a of the movable die 52 and the fixed die 42.

A concave portion 54 provided near the outer periphery of the die 42 a engages with the convex portion 44 to center both dies 52 , 42 . Since these uneven portions 54 and 44 can be processed with high precision as described above, the centering of both dies 52 and 42 is reliably performed on the micron order. This centering not only aligns the mold center O within a predetermined accuracy, but also
By providing three or more locations, positioning in the rotational direction around the mold center O is also performed.

Therefore, it is effective for lens molding, such as a rectangular lens, in which the rotation angle positions of the upper and lower lens surfaces must be determined in a predetermined relationship.

In addition, if low friction bodies 46 and 56 are interposed between the Guiplay) 41 and 51 and the heat insulating shafts 3 and 8, the mold assemblies 4 and 5 can be moved relatively easily, thereby preventing the occurrence of distortion. This enables more accurate centering. Incidentally, the space between the die plates 41, 51 and the heat insulating shaft 3.8 may be simply tightened and fixed using a normal pole E.

FIG. 4 shows another embodiment of the present invention, and 420 is a fixed die corresponding to the fixed die 42 shown in FIG. The convex portion 440 provided on the end surface 420a of the fixed die 420 is fan-shaped so that both side surfaces 440a coincide with straight lines OA and OB extending in the radial direction from the mold center O. If formed in this way, when the fixed die 420 thermally expands, the point M on the side surface 440a moves on the straight line OA and moves to, for example, a point, so that both side surfaces 440a of the convex portion 440 are free from thermal expansion. Always on the straight lines OA and OB. Therefore, if the concave part of the movable die (not shown) is formed to correspond to the convex part 440, the same can be said about the concave part, even if there is a difference in thermal expansion between the fixed die and the movable die. Centering can be performed without being affected by this. In addition, the...inching part C in Fig. 4 is
In processing the convex portion 440, it is a relief portion formed slightly lower than the end surface of the annular central portion surrounding the die piece 43.

5 to 8 show still other embodiments of the present invention, in which FIGS. 5 and 6 correspond to the lower mold assembly 5 in FIG. 2, and FIGS. 7 and 8 correspond to the lower die assembly 5 in FIG. This corresponds to the upper mold assembly 4 in FIG. 5, a recess 54' is formed by attaching a fan-shaped piece 57, which is slightly thinner than the dimension of the step, to the step 52C with a screw 58 and a fixing pin 59.

The upper die assembly 4' shown in FIGS. 7 and 8 is constructed by attaching a fan-shaped piece 47, which is slightly thinner than the step dimension, to the end surface 42a' of the fixed die 42' using screws 48 and fixing pins 49. 44'.

The pieces 57 and 47 are attached to both dies 52 with one attached to the movable die 52' or the fixed die 42' and the other not attached.
'+42''r Combine them facing each other, and insert the other unattached piece 57-i (47) between one piece 47 and 57 and temporarily fix it with adhesive C or move it. After temporarily fixing the die 52' or the fixed die 42' with screws (not shown) from the back side, opening both the dies 02' and 42' and properly attaching the other piece 57 or 47, the uneven parts 54' and 44' are formed. can be formed with extremely high precision.

In order to prevent deterioration of centering accuracy due to thermal expansion, the pieces 47 and 57 are preferably made of the same material as both dies 4Ql and 521, or at least both stations 47 and 57 are made of the same material.

Also, one of the pieces 47 and 57 is not considered a piece,
Similar to the fixed die 42 or the movable die 52 shown in FIG. 2, it may be formed integrally with the fixed die 42' or the movable die 52', and only the other piece may be the piece 47 or 57.

In the above-mentioned embodiment, a pair of upper and lower molds is used as the Goui plate 41. -51. Although an assembled type formed by fixed and movable dies 42, 52, die pieces 43, 53, etc. has been shown, it goes without saying that an integral type may be used.

〔Effect of the invention〕

As described above, according to the present invention, a pair of upper and lower molds can be centered with high precision. Furthermore, since this centering is performed between the molds, it is not necessary to form the supporting and opening/closing parts of both molds with high precision, and the manufacturing and maintenance of the device can be facilitated.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the glass lens molding apparatus according to the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. FIG. 4 is a plan view of a fixed die showing another embodiment of the invention, FIGS. 5 to 8 show still other embodiments of the invention, and FIG. FIG. 6 is a plan view of the assembly, FIG. 6 is a front view of FIG. 5, FIG. 7 is a plan view of the upper mold assembly, and FIG. 8 is a front view of FIG. 7. 2...Fixed shaft, 3,8...Insulated shaft, 4,
4'... Upper die assembly (upper die), 5,5'...
・Lower mold assembly (lower mold), 6... Mold clamping device, 7...
...Movement axis, 41, 51...Die plate,
42, 42', 420...Fixed die, 4
2a, 42a', 52a, 52a',
420a... End face, 43, 53...
Die piece, 44, 44', 440...
Convex portion, 44a, 54a, 440a...
...Side surface, 46, 56...Low friction body, 47
, 57... Piece, 52, 52'... Moving die, 54, 54'... Recess.

Claims (1)

[Scope of Claims] 1. In a glass lens molding apparatus using a pair of upper and lower molds, three or more molds are provided near the outer periphery on one end surface of the molds facing each other, and the outer periphery side and the end surface side are open. It has a concave portion extending substantially radially from the center of the mold, and a convex portion provided on the other end surface corresponding to the concave portion, respectively,
A glass lens molding apparatus, wherein the uneven portion is formed such that a side surface of the uneven portion has a predetermined fitting precision at least when the mold is in a closed state. 2. The glass lens molding apparatus according to claim 1, wherein the side surface extends in a radial direction from the center of the mold. 3. The glass lens molding apparatus according to claim 1 or 2, wherein at least one of the concave and convex portions is formed by a piece assembled into a mold. 4. The glass lens according to claim 1, 2 or 3, wherein the joint between the mold and the shaft for attaching the same mold is formed so as to be slightly movable in the radial direction with respect to the center of the mold. Molding equipment.