JPS61261222A - Apparatus for producing optical element - Google Patents

Abstract

PURPOSE:To obtain an optical element free of sink mark and having high dimensional accuracy, continuously by a hot press, by supplying the raw material from the hopper to the space between a pair of vertically arranged molding means using a transfer screw. CONSTITUTION:The raw material 23 is charged into the hopper 21. The thermally insulated housing 1 is closed by closing the door 2, the vacuum pump placed on the table 4 is operated to evacuate the housing 1, and the raw material 23 is heated by electrifying the heater 25. The transfer screw 17 is rotated with the driving apparatus 19 and the driving shaft 18, and the raw material 23 is transferred from the outlet port 22 of the hopper 21 to the side hole 8 of the holder 6, sent via the inclined face 20, dropped into the lower hole 10 of the holder 6 and placed on the forming face of the lower molding member 13. the air cylinder 12 is actuated to drop the upper molding member 11 against the lower molding member 13 to effect the molding of the raw material 23. The molded product is dropped from the top part at the center 31 of the tray member 28 to the receiving cavity 32 by raising the member 11 and slowly lowering the member 13.

Description

[Detailed description of the invention] 111 Tatsu ■ Moon dog! The present invention relates to a novel apparatus for molding optical elements under heat and pressure.

Conventional techniques and in between Traditionally, to manufacture glass optical elements, molten or softened glass is placed in a mold and pressure molded, or
The glass material is placed in a mold, heated together with the mold, and then press-molded at a predetermined temperature. When pressure molding molten or softened glass, it is difficult to obtain highly accurate optical elements due to "sink marks," and with methods that heat the glass material together with the mold, it is difficult to obtain highly accurate optical elements. It is possible to do this, but it takes an hour and there is a cost problem.

. An object of the present invention is to provide a novel apparatus that can continuously heat and press mold high-precision optical elements without "sink marks."

According to the invention, the above object comprises: a sealable insulated housing; upper and lower mold means disposed within the insulated housing and cooperating to form the desired mold cavity;
means for relatively driving these upper and lower mold means; a material supply means installed in the housing for feeding a material between the upper and lower mold means when they are separated from each other; means located within the housing for heating the material before it is placed between the upper and lower mold means; and means located within the housing for receiving the molded article. This is achieved by providing an optical element manufacturing apparatus that performs the following steps.

In a preferred embodiment of the invention, the material supply means comprises a hopper containing a plurality of materials, and a heat-resistant feed screw means extending between the outlet of the hopper and the area between said upper and lower mold means. The material can be supplied at regular intervals.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 1, the optical element molding apparatus shown here includes a heat insulating housing 1 which can be sealed by a door 2. This housing l is mounted on a movable base 4 having casters 3. Note that it is preferable that the door 2 is provided with a heater (not shown).

Inside the housing l, there is a fixed frame 5, on which a holder 6 is installed.

The holder 6 has a vertical hole 7 and a lateral hole 8 intersecting the hole 7 at right angles. The vertical hole 7 is divided into an upper hole portion 9 and a lower hole portion 10 with a horizontal hole 8 as a boundary.

A rod-shaped upper mold member 11 protrudes into the upper hole portion 9, and the lower end of this upper mold member has a molding surface capable of molding the functional surface of the optical element to be molded. The upper mold member 11 is moved downward by an air cylinder 12 installed outside the housing. Similarly, a rod-shaped lower die member 1 is provided in the lower hole portion 10.
3 protrudes, and its lower end also has a molding surface for molding the functional surface of the optical element to be molded. The lower mold member 13 can be moved within the lower hole portion 10 and set in a predetermined position by suitable means (not shown), such as an air cylinder.

It is preferable that this holder 6 is also provided with a heater as will become clear later. A material supplying means 16 is connected to the horizontal hole 8 of the holder 6, and this material supplying means is made of heat-resistant material such as molybdenum. It includes a lead screw 17 made of metal. This feed screw 17 is made to rotate once every fixed period of time by a drive device W19 installed outside the housing via a drive shaft 18. The end of the feed screw 17 on the holder side is connected to an inclined surface 2o in the horizontal hole, and as will be explained later, the fed spherical glass material rolls down this inclined surface 2o and enters the lower hole portion lo of the holder. The mold member 13 is inserted into the mold member 13 and rests on the molding surface of the lower mold member 13 therein.

A discharge port 22 of a hopper 21 is connected to the opposite end of the feed screw 17, and this hopper 21 accommodates a plurality of spherical glass materials 23. Therefore, when the feed screw 17 is rotated by the drive device 19, the raw materials 23 are sent out one by one from the discharge port 22 of the hopper 21, and are transferred toward the horizontal hole 8 of the holder 6 as the feed screw 17 rotates. .

As best seen in FIG. 2.3, a pair of reflectors 24 are installed near the top of the feed screw 17, and the opposing inner edges of these reflectors 24 are separated from each other.
It constitutes a moving path for the glass material 23. An infrared heater 25 is installed adjacent to the upper surface of each reflecting plate 24, and is capable of heating the glass material 23 being fed.

The lower mold member 13 also passes through a central hole 29 of a tray member 28 that receives the molded product, and this tray member 28 includes an annular wall 3o standing upright from its periphery and a central portion 31 having a conical head shape. As will be explained later, after the glass material is molded, when the lower mold member 13 is lowered and the molded product reaches the top of the central conical portion 31 of the tray member 28, a pushing means (not shown) is pressed. The molded product is pressed and the center part 31
A depression 32 created at the base of an upright wall by rolling down the slope of
It is designed to enter. A large number of these recesses 32 are provided in the circumferential direction of the tray member 28, and during the molding operation, the recesses 32 receive molded products that fall one after another as the tray member 28 is rotated or indexed. It looks like this.

During the molding operation, a glass bulb that has been polished in advance is placed in the hopper 21, the door 2 is closed, and the heat insulating housing 1 is hermetically sealed.Next, the vacuum pump (not shown) installed in the base 4 is activated. The air inside the housing 1 is drawn to bring the interior to, for example, 10-2 Torr.While maintaining this degree of vacuum, the infrared heater 25 and other heaters are energized to heat the glass bulb 23.Next, the feed screw 17 is heated. The glass bulb 23 starts to be sent by rotating. The feeding speed and heating temperature are set so that the glass bulb material 23 is heated to 520° C. when it approaches the entrance of the horizontal hole 8 of the holder 6.

The frontmost glass bulb 23 rolls down the inclined surface 20 and reaches the holder 6.
Once it falls into the lower hole portion lO of the lower mold member 13 and rests on the molding surface of the lower mold member 13, the lower mold member 13 is fixed at the position shown in the figure.Next, the air cylinder 12 is operated to move the upper mold member 11 into the lower mold It is lowered towards member 13 and pressed. As a result, the glass bulb is press-molded. The molding pressure is, for example, about 1
00 kg/crn' and the molding time is about 1 minute. At this time, the wall surface of the lower hole portion IO of the holder 6 acts as a mold. Therefore, as mentioned above, the holder 6
It is preferable to provide a heater.

After the molding is completed, the upper mold member 11 is raised and the lower mold member 13 is gradually lowered, and when it approaches the top of the central part 31 of the tray member 28, a pushing means (not shown) pushes the molded product onto the tray member 28. In this way, the glass bulbs 23 in the hopper 21 are formed one after another. When there are no more glass bulbs in the hopper 21, the heater 25 is deenergized, the vacuum valve is closed, and the inside of the housing 1 is When cooled, air is introduced into the interior through suitable pipe means, then the door 2 is opened and the molded article is removed.

Using this molding device, from the glass type 5F14, as shown in Fig. 4, an outer diameter of 5 mm, a center thickness of 3.02 mm, an aspheric surface between the first surfaces, a reference R = 4.198, and a spherical surface on the second surface. R=
3.075, and a focal length f=5.51 was molded. This lens had the desired high precision optical properties.

As described above, the molding apparatus according to the present invention can continuously manufacture optical elements with high precision.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a molding apparatus according to the invention. FIG. 2 is a fragmentary plan view showing an enlarged feed screw portion of the molding device shown in FIG. 1. FIG. 3 is a sectional view taken along the line -m in FIG. 2. FIG. 4 is a diagram showing an example of a molded lens. In the drawings, 1... heat insulation housing, 2... door, 3... caster, 4... base, 6... holder,
7...Vertical hole, 8...Horizontal hole. 11... Upper mold member, 12... Air cylinder, 13.
...Lower die member, 16...Material supply means, 17...Feed screw, 18...Drive shaft, 19...Drive device, 21
...Hopper, 24...Reflector, 23...-Heater agent Patent attorney Seki Yamashita Figure 1 Figure 2 1!7 Figure 3 Figure 4I! L

Claims (2)

[Claims] (1) A sealable heat insulating housing, upper and lower mold means disposed within the heat insulating housing and cooperating to form a desired mold cavity, and relatively driving these upper and lower mold means; a material supply means installed in the housing for feeding a material between the upper and lower mold means when they are separated from each other; An apparatus for manufacturing an optical element, comprising: means for heating the mold before being placed between the mold means; and means located within the housing for receiving the molded article. (2) In the optical element manufacturing apparatus according to claim 1, the material supply means is between a hopper containing a plurality of materials, and an area between the discharge port of the hopper and the upper and lower mold means. 1. An optical element manufacturing apparatus comprising: a heat-resistant feed screw means extending in the direction of the feed screw, and capable of supplying materials at regular intervals.