JP2836230B2 - Lens molding equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens forming apparatus for forming a lens on an optical glass material by pressing means, and more particularly, to a method for uniformly heating the optical glass material during the forming. The present invention relates to a lens forming apparatus described above.

[Prior art] In recent years, optical glass lenses have been used for conventional grinding and grinding.
In addition to the method of processing by polishing, the method of directly pressing the molten optical glass with the mold, or the method of press molding by softening the optical glass material preformed in advance to a shape close to the final shape in the mold The system which does it is coming to be used. Among these methods, the press molding method is advantageous from the viewpoint of labor-saving production, automation, and the like. In particular, the method of press molding using a preformed optical glass material is simple in terms of processing. Most promising in the future.

Here, in order to form a lens from a preform glass material by a pressing method, usually, each of the steps of atmosphere replacement, heating, pressing, and cooling is performed while the glass material is loaded in a molding die. is necessary.

Atmosphere replacement is to replace at least on and near the molding surface of the mold with an inert gas atmosphere composed of, for example, nitrogen gas, in order to prevent an oxide film from depositing on the molding surface of the preform mold. . The whole of the thus-replaced mold is heated in a heating chamber to soften the glass material loaded in the mold into a uniform state. Thereafter, the glass material is formed by applying a pressing force to the molding die, and the molded product is cooled and taken out of the die.

The molding die is usually composed of a fixed lower die, an upper die that can be displaced up and down in a direction approaching and separating from the lower die, and a body die that guides the elevating operation of the upper die. A molding section into which the glass material is loaded is defined between the upper mold and the upper mold. The mold is set on a transport plate and transported sequentially to each of the steps described above. Also,
The transfer plate is formed of a plate having extremely good thermal conductivity in order to efficiently heat the glass material by transmitting heat from a heater provided in the heating chamber to the mold.

[Problems to be Solved by the Invention] One of the most important conditions in molding using the preform glass material described above is that the entire glass material is heated to a uniform state. For this purpose, not only the glass material but also the entire mold is heated so that both the mold and the glass material have the same temperature. Therefore, as a mold for glass material,
Generally, a member having a high thermal conductivity, such as tungsten carbide, is preferably used.

By the way, the above-mentioned heating chamber for heating the glass material has a certain amount of space. In this space, no matter how many heaters are provided, the entire chamber is heated to a uniform temperature. It is difficult to keep in state and there is an uneven distribution of heat in this chamber. Since the mold is exposed in the heating chamber, a partial temperature difference occurs in the mold due to the uneven distribution of heat in the chamber. When such a temperature difference occurs, it causes uneven heating of the glass material, and has a drawback such that distortion or the like occurs at the time of molding to deteriorate the quality.

The present invention has been made in view of the above points, and an object of the present invention is to provide a lens forming apparatus capable of heating an entire glass material to an extremely uniform state. .

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a configuration in which a heat-insulating cylinder surrounding a body die of a molding die with a predetermined gap is arranged on a conveying plate of the molding die. The feature is that it is.

[Operation] With this configuration, the inside of the heat insulating cylinder is formed into a very small small chamber in the heating chamber. Therefore, the temperature distribution of the molding die located inside the small chamber, particularly, the temperature distribution of the portion where the glass material is loaded is almost uniform. As a result, the entire glass material is heated uniformly, and the molding accuracy can be significantly improved.

And, in order to further uniform the temperature of the small chamber formed in the heat insulating cylinder and to heat it more efficiently, as close as possible to the upper mold, as long as the movement of the mold is not hindered. What is necessary is just to arrange in a position.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, FIG. 3 shows a schematic configuration of the entire lens forming apparatus.

In the drawing, 1 is a work set part, 2 is an atmosphere replacement part, 3 is a heating part, 4 is a press part, 5 is a cooling part, and 6 is a product take-out part.

The preformed optical glass material 10 is to be loaded into the lens forming unit shown in FIGS. 1 and 2. The lens forming unit includes a transfer plate 11 made of a rectangular plate and a mold 12 installed on the transfer plate 11. Where the transport plate
Reference numeral 11 denotes a member having a high thermal conductivity so that heat from a heater (not shown) provided in the heating unit 3 and the pressing unit 4 can be efficiently transmitted to the molding die 12. Is formed. This transport plate 11 is transported by an appropriate transport method,
For example, the workpiece is transported along an endless transport path, or is transported from the work setting section 1 to the product take-out section 6 through each section sequentially by feeding the frames.

The molding die 12 is a lower die fixedly installed on the transport plate 11.
12a, an upper die 12b that can be displaced up and down in a direction to approach and separate from the lower die 12a, and a trunk die 12c that guides the upper die 12b.
The optical glass material 10 is loaded into a molding portion 13 formed between the lower mold 12a and the upper mold 12b. Therefore, the molding die 12 and the transport plate 11 constitute a molding die unit.

In order to prevent an oxide film from being formed on the surface of the optical glass material when performing lens molding, particularly during heating and pressing, the inside of the heating unit 3, the pressing unit 4, and the cooling unit 5 are It is placed under an inert gas atmosphere.

In the optical glass material setting section 1, the transport plate 11
The optical glass material 10 is loaded into the molding portion 13 of the molding die 12 provided above, and is first sent to the atmosphere replacement portion 2, and air is discharged from the molding portion 13 in which the optical glass material 10 is loaded, Replace with an inert gas atmosphere. Next, the mold unit is conveyed and sent to the heating unit 3, where the optical glass material 10 is heated to a predetermined temperature in a heating chamber constituting the heating unit 3 and softened. After that, it is conveyed to the press section 4 where the upper die 12 is pressed.
The optical glass material 10 softened by pressing b
Press molding. Then, after the press molding is completed, the upper mold 12b is separated from the optical glass material 10, cooled by the cooling unit 5, moved to the product removal unit 6, and the molded product is removed from the molding die 12.

Here, in forming the optical glass material 10 described above, the heating unit 3 heats the optical glass material 10 to a predetermined temperature.
It is necessary to control so that the temperature of the whole 10 becomes uniform. If the temperature is too high or too low, the quality cannot be stabilized, and if the heating is not uniform, the shape will be distorted and the quality will deteriorate. .

Therefore, in order to enable uniform heating of the optical glass material 10, the heat insulating cylinder 14 is provided on the transport plate 11 outside the body mold 12c so as to surround the body mold 12c. The heat insulating cylinder 14 is made of a member having good heat insulating properties such as stainless steel and ceramics, and the heat insulating cylinder 14 is, for example, 1 mm or less with respect to the body mold 12c,
They are arranged with a very small gap 15. Then, the gap 15 is maintained in a uniform state over the entire
Insulation tube 1
4 has an inward cut portion 14a formed at the lower end thereof.
By closely fitting a to the outer surface of the trunk mold 12c, the centering between the heat insulating cylinder 14 and the trunk mold 12c is performed. As a result, the mold 12 is placed in a very small chamber.

Therefore, in the relatively wide chamber of the heating unit 3,
Even if there is uneven distribution of temperature inside this chamber, it is defined by the heat insulating cylinder 14 and the mold 12 is formed inside.
The heat is prevented from being dissipated to the outside by the heat insulating cylinder 14 and the gas interposed between the heat insulating cylinder 14 and the body mold 12c. The state is maintained, and the entire optical glass material 10 is uniformly heated. Thus, when the optical glass material 10 is pressed to form a lens, no distortion or the like occurs in the lens.

Further, in the heating section 3 described above, the upper heater 16
Is provided. The upper heater 16 is arranged at a position as close as possible to the upper mold 12b as long as the molding die 12 does not interfere with the passage, for example, at an upper position with a gap of about 1 mm or less from the upper surface of the upper mold 12b. It is provided to be able to ascend and descend so that it can be installed.

Therefore, the transfer plate 11 with which the mold 12 is in direct contact
Is heated from below, and the upper heater 16 heats the molding die 12 from a position immediately above the molding die 12.
12 can be heated, and the heat from these upper and lower heat sources is
As a result, the optical glass material 10 can be heated very efficiently and uniformly as a whole, and the quality of the lens molded product can be further improved.

[Effects of the Invention] As described above, the present invention has a configuration in which the heat insulating cylinder surrounding the body with a predetermined gap is provided outside the body of the mold, so that the arrangement of the mold is provided. The portion can be a very small chamber that is thermally isolated from the outside, and the entire glass material can be heated to an extremely uniform state.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention, wherein FIG. 1 is an external view showing an entire configuration of a lens forming unit, FIG. 2 is a sectional view of FIG. 1, and FIG. FIG. 3 is an explanatory diagram showing a configuration. 1: Optical glass material setting part, 2: Atmosphere replacement part, 3: Heating part, 4: Press part, 5: Cooling part, 6: Product take-out part, 10: Optical glass material, 11: Transport plate, 12: Mold , 12a: lower mold, 12b: upper mold, 12c: trunk mold, 13: molded part, 14: heat insulating cylinder, 15:
Gap, 16: upper heater.

Claims (2)

(57) [Claims] 1. A mold having an upper mold, a lower mold, and a body mold is set on a transfer plate having thermal conductivity, and an optical glass material loaded between the upper mold and the lower mold is heated and softened. Let me
A lens forming apparatus for performing lens forming by applying pressure, wherein a heat insulating cylinder surrounding the body mold at a predetermined interval is disposed on the transport plate. 2. An apparatus according to claim 1, wherein the upper heater is disposed in the heating chamber so as to be located at a position facing the upper mold with a slight gap. Lens molding equipment.