JP2000169159A - Device and process for forming glass element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit sink marks from being caused without causing any positional deviation of the molds from each other in the device and process, using a pair of opening/closing type molds that can be abutted on each other. SOLUTION: In this device, of a pair of opening/closing type upper and lower molds 10 and 20, that can be abutted on each other, the lower mold 20 comprises a mold main body consisting of a die plate 21 and die 22, and a core 23 fitted to the mold main body so as to be vertically movable by a lower movement shaft 51 and a movable plate 25. Also, this process comprises placing a glass material 30 between these upper and lower molds 10 and 20, heating the molds 10 and 20 and the glass material 30, thereafter, placing the core 23 at its lowest position and closing the main body of the lower mold 20 and the upper mold 10 by abutting them on each other to perform initial press forming, and in that closed state of the main body of the lower mold 20 and the upper mold 10, elevating the core 23 with the lower movement shaft 51 to perform final press forming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus and a molding method for glass elements such as glass lenses and prisms. More particularly, the present invention relates to a method of arranging a glass material between a pair of openable molds that can abut each other. The present invention relates to a glass element molding apparatus and a molding method for molding a glass element by heating a mold and a glass material and pressing the glass material.

[0002]

2. Description of the Related Art Glass elements such as glass lenses, which require high precision, are manufactured by grinding and polishing a glass material obtained by molding a molten glass into a shape close to a final molded product, and a glass glass which is similarly melted. Can be roughly classified into two types: a glass material molded into a weight and a shape corresponding to the final molded article, and heated (pressed by a precision mold (reheat press)) to finish.

[0003] Manufacturing by grinding and polishing requires more than a dozen steps for forming a curved surface, generates a large amount of glass grinding powder harmful to the operator, and has a high value-added aspherical optical surface. It has drawbacks such as difficulty in mass-producing glass elements having surfaces with the same precision.

On the other hand, the reheat press is a method of transferring a shape of a mold to a glass material to form a glass element, so that only one step of press forming is necessary for forming a curved surface, and at the same time, clean processing is performed. It has the advantage that it can be manufactured in an environment and that once a mold is manufactured, a large number of glass elements conforming to the accuracy of the mold can be manufactured in large quantities.

[0005]

As shown in FIG. 3 (a), an apparatus for forming a glass element used in a reheat press is provided between a pair of openable / closable dies 10, 20 which can be brought into contact with each other. Generally, a method of forming a glass element 31 by arranging a plurality of glass materials 30 and pressing these glass materials 30 with molds 10 and 20 is used. In the cooling step after molding, the glass element 31 shrinks, and as shown in FIG. 3B, a shrinkage gap (commonly referred to as sink) 32 is formed in the molded glass element 31, so that the shape of the mold is completely transferred. Can not do it.

In FIG. 3, reference numerals 11 and 21 denote metal die plates, and reference numerals 12 and 22 denote metal dies. Reference numerals 13 and 23 denote core portions made of ceramic, cemented carbide, or the like, have molding surfaces 13a and 23a, and are integrally held in the dies 12 and 22 by the die plates 11 and 21. 14 is a positioning pin and 24 is a positioning hole.

As a method of improving the sink mark, there is a method in which the mold has a so-called barrel-shaped structure, and the upper and lower molds provided in the barrel are continuously pressed even during the cooling step. However, since the molding device having the body-shaped structure can mold only one glass element in one molding, there is a problem in tact time, and
It has drawbacks such as difficulty in carrying in and out of the glass material and the formed glass element with respect to the mold.

Further, the openable molds 10 and 20 shown in FIG.
In the press forming by using
Leave a small gap without completely closing 0, 20,
There is also a molding method in which the generation of sinks is suppressed by applying a pressing force during the cooling process to the vicinity of the transition point in the subsequent cooling step, but in this case, the guide portions for opening and closing the dies 10 and 20 have a small amount. Since there is a gap in the direction perpendicular to the guide direction, the mold 10 and the mold 20 are displaced as shown in FIG.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress the occurrence of sink marks in a glass element forming apparatus and a forming method using a pair of openable and closable molds which can be brought into contact with each other as described above, without causing displacement of the molds. .

[0010]

According to a first aspect of the present invention, there is provided an apparatus for forming a glass element, comprising the steps of: placing a glass material between a pair of openable and closable dies; In a glass element forming apparatus for forming a glass element by heating and pressing a glass material, at least one of the pair of molds has a mold body and a molding surface and is movable back and forth in the pressing direction. A mold opening and closing device for opening and closing the other of the pair of dies and the mold body, and pressing the core against the mold body. And a control unit for controlling the operation of the mold opening / closing device and the core unit driving device for moving back and forth in the direction and pressing toward the other mold.

According to this apparatus, the mold can be closed without generating a large pressing force by retracting the core portion and closing the one mold body and the other mold by the mold opening / closing device. Can be closed without displacement. Further, the core section can be operated independently of the mold closing by the core section driving device operated by the control section, thereby suppressing the occurrence of sink in the cooling step.

The mold body is fixed, and the other mold is configured to be moved back and forth in the pressing direction with respect to the mold body by a mold opening / closing device. It is preferable to be configured to move back and forth and press.

Further, in the method for forming a glass element according to the present invention for achieving the above object, a glass material is disposed between a pair of openable and closable molds which can contact each other, and the mold and the glass material are heated. Thereafter, the core portion is placed at the retracted position, the mold body and the other mold are closed by a mold opening / closing device to perform initial press molding, and then the core portion is closed with the mold body and the other mold closed. It is advanced by a drive device to perform final press molding.

According to this molding method, a highly accurate glass element having no displacement and having no sink can be formed by a glass element molding apparatus using an openable / closable mold that can abut against each other.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, a servo motor 41 is used as a drive source on an upper portion of a frame 40,
A driving device (mold opening / closing device) 4 such as a screw jack for converting the rotational motion of the servo motor 41 into a linear motion thrust.
2 are installed. An upper moving shaft 44 is attached to the driving device 42 via a load detecting device 43.
A mold (upper mold) 10 similar to the mold 10 shown in FIGS. 3 and 4 is attached to the lower end of the upper moving shaft 44 in FIG. 1 via a heat insulating cylinder 45 made of ceramic.

An intermediate plate 40a on the lower side of the frame 40
Is provided with a mold mounting seat 46.
Is connected to the lower mold 20 via a heat insulating cylinder 47 similar to the heat insulating cylinder 45.
Is attached. The lower mold 20 has a die plate 21, a die 22, a plurality of cores 23, and a positioning hole 24 as shown in FIG. 2A in an enlarged manner. It is the same as the conventional mold 20 except that the core part 23 in the present apparatus is a die plate 21.
The die 22 is movably mounted in the pressing direction, that is, in the vertical direction in FIG. The lower end of the core portion 23 in FIG.
It is supported by a movable plate 25 that is vertically movable inside.

Returning to FIG. 1, at the bottom of the frame 40,
The servo motor 48 is used as a drive source.
A drive device (core drive device) 49 such as a screw jack that converts the rotational motion of the motor into a linear motion thrust is attached, and a lower moving shaft 51 is attached to the drive device 49 via a load detection device 50. In FIG. 1, the upper end of the lower drive shaft 51 is connected to the movable plate 25.

A bracket 52 which is vertically moved by a driving device (not shown) is movably engaged with the upper moving shaft 44, and a transparent quartz tube 53 surrounding the molds 10 and 20 is attached to the bracket 52. I have. This transparent quartz tube 5
3 has a lower end in contact with the upper surface of the mold mounting seat 46, and
An airtight molding chamber 54 is formed around 0. The bracket 52 includes a mold 10 surrounding the transparent quartz tube 53.
A lamp unit 55 for heating the glass material 30 shown in FIG.

The upper and lower moving shafts 44 and 51 are provided with a molding chamber 54.
Supply path 5 for supplying an inert gas in order to make the inside an inert gas atmosphere and to cool molds 10 and 20
6, 57 are provided. In addition, the mold mounting seat 46 includes:
A supply path 58 for similarly supplying an inert gas is provided between the lower heat insulating cylinder 47 and the lower moving shaft 51, and an exhaust port 59 for exhausting air and an inert gas from the molding chamber 54 is provided. Is provided.

Reference numeral 60 denotes a control unit, which is a load detecting device 43;
50 and the outputs of the thermocouples 61 attached to the lower mold 20. The servo motors 41 and 48 are driven by these outputs and a separately provided program to drive the speeds of the upper and lower moving shafts 44 and 51, The position and the pressing force are controlled, and the output of the lamp unit 55 and the supply of the inert gas are controlled to perform desired molding.

Next, the method of forming a glass element according to the present invention will be described together with the operation of the present apparatus. The lower moving shaft 51 is lowered to move the movable plate 25 as shown in FIG.
In the retracted position. In this state, the glass material 30 is placed on the core portion 23 of the lower mold 20, a molding chamber 54 is formed by a transparent quartz tube 53, and an inert gas is supplied from supply paths 56, 57, 58 to form the inside of the molding chamber 54. Into an inert gas atmosphere, and the lamp unit 55 is used to form the molds 10, 20 and the glass material 3
Heat 0.

When the temperature of the mold 20 is stabilized at a predetermined press temperature, the upper moving shaft 44 is lowered, and as shown in FIG. 2 (b), the molds 10 and 20 are completely closed and the initial press is started. Do. At this time, since the core portion 23 of the lower mold 20 is at the retracted position, the glass material 30 is not completely crushed. Therefore, only a light load acts between the mold 10 and the mold 20, and the two molds 10 and 20 are accurately positioned by the positioning pins 14 and the positioning holes 24 without any positional displacement.

Next, the lower moving shaft 51 is raised while maintaining the mold closing force of the upper moving shaft 44 at a predetermined level, and the movable plate 25 is pushed up as shown in FIG. I do.

Next, the output of the lamp unit 55 is reduced, and the supply amount of the inert gas from the supply paths 56, 57, 58 is controlled to lower the temperatures of the dies 10, 20 at a predetermined temperature gradient, and the process proceeds to a cooling step. However, even during this cooling step, the pressing by the core portion 23 is continued while controlling the pressing force by the lower moving shaft 51.

When the temperature of the mold 20 has decreased to near the transition point temperature, the pressing force of the lower moving shaft 51 is released, and when the temperature of the mold 20 further decreases, the molds 10 and 20 are opened and the molding chamber 54 is opened. The supply of inert gas to the
The molding chamber 54 is opened and the glass element 31 is taken out.

In the above description, an example in which the final pressing by the core portion 23 is performed before shifting to the cooling step has been described. However, since the final pressing may be performed at a pressable temperature, the final pressing is performed after shifting to the cooling step. You may. Further, in the above-described embodiment, an example is described in which the die plate 21 and the die 22 that are the die main bodies of the lower die 20 are fixed to the intermediate plate 40a of the frame 40, and the core part 23 and the upper die 10 of the lower die 20 are moved. As shown, the die plate 11 and the die 12 which are the main body of the upper die 10 are fixed, and the core 13 and the lower die 20 of the upper die 10 are fixed.
Is moved, or the entire upper mold 10 is fixed, and the lower mold 20 is moved.
The die plate 21 and the die 22, which are the main bodies of the mold, and the core part 23 are separately moved, and, on the contrary, the entire lower mold 20 is fixed. Each of them may be moved separately.

Example A spherical lens having a diameter of 13 mm and a double-sided R (radius) of 27 mm was molded using an eight-cavity mold. The shape accuracy of the molding surfaces 13a, 23a of the cores 13, 23 of the dies 10, 20 is λ
/ 8, and the glass material used was BK-7 (manufactured by OHARA CORPORATION, transition point 565 ° C., yield point 624 ° C.).

After the temperature of the mold 20 was stabilized by heating to 690 ° C., the upper moving shaft 44 was moved to close the molds 10 and 20, and an initial pressing was performed by applying a pressing force of 800 kgf. Next, the lower moving shaft 51 is raised to
To perform a final press, and press the lower moving shaft 51 with a pressing force of 30 to a temperature near the transition point during the cooling process.
It was kept at 0 kgf.

This molding method was performed 100 times, and the shape accuracy of the formed glass element 31 was measured. As a result, it was λ / 8, and the accuracy of the mold, that is, the molding surface 13 of the core portions 13 and 23 was measured.
It was confirmed that the shape precisions of a and 23a were almost completely transferred, and no displacement of the optical axes of both lens surfaces due to the displacement of the mold 10 and the mold 20 was observed.

On the other hand, when the molding was performed under the same conditions as in the above embodiment except for the single-stage press using the conventional mold shown in FIG. 3, sink marks appeared, the shape accuracy was about λ / 2, and Transferability was insufficient. In addition, as shown in FIG.
In the case where the pressing was continued to the vicinity of the transition point without completely contacting 0, the shape accuracy could be greatly improved to about λ / 6, but since the positioning pin 14 did not function, the optical axis was shifted. Was observed.

[0031]

As described above, according to the present invention, it is possible to obtain a plurality of glass elements, which is an advantage of a glass element molding apparatus using a pair of openable and closable molds which can be brought into contact with each other. In addition, while taking advantage of the advantage that the glass element can be easily loaded and unloaded, an effect is obtained in which high-precision molding can be performed by suppressing both the generation of sink marks and the displacement of the mold, which are the drawbacks.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a glass element forming apparatus according to the present invention.

2 is an enlarged view of a mold portion of the device shown in FIG. 1,
(A) is a figure which shows a mold open state, (b) is an initial press state which closed only the mold main body, (c) is a figure which shows the final press state by a core part.

3A and 3B are enlarged views of a mold portion of a conventional glass element forming apparatus, wherein FIG. 3A shows a mold open state and FIG. 3B shows a mold closed state.

FIG. 4 is a view showing a state of displacement of the mold shown in FIG. 3;

[Explanation of symbols]

10 Upper mold 11 Die plate
12 die 13 core part 14 positioning pin 20 lower die 21 die plate
22 die 23 core part 24 positioning hole
25 movable plate 30 glass material 31 glass element
32 sink 40 frame 41 servo motor
42 drive device 43 load detection device 44 upper moving axis
45 Insulated cylinder 46 Type mounting seat 47 Insulated cylinder
48 Servo motor 49 Driving device 50 Load detecting device
51 Lower moving shaft 53 Transparent quartz tube 54 Molding chamber
55 Lamp unit 56, 57, 58 Supply path of inert gas
59 exhaust port 60 control unit 61 thermocouple

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takashi Matsumoto 2068-3 Ooka, Numazu-shi, Shizuoka Pref. Toshiba Machine Co., Ltd. Numazu Office

Claims (3)

[Claims] An apparatus for forming a glass element, wherein a glass material is arranged between a pair of openable and closable molds that can be brought into contact with each other, and the glass element is formed by heating the mold and the glass material and pressing the glass material. In at least one of the pair of molds, a mold body and a core portion having a molding surface and attached to the mold body so as to be movable back and forth in a pressing direction, A mold opening and closing device for opening and closing the other mold and the mold body; and a core part driving device for moving the core part back and forth in the pressing direction with respect to the mold body and pressing the core part toward the other mold. And a control unit for controlling operations of the mold opening / closing device and the core unit driving device. 2. The mold body is fixed, and the other mold is configured to move back and forth in the pressing direction with respect to the mold body by a mold opening / closing device, and the core part is a core part in the mold body. The apparatus for forming a glass element according to claim 1, wherein the apparatus is configured to be moved back and forth and pressed by a driving device. 3. A glass material is arranged between a pair of openable and closable molds that can be brought into contact with each other, and after the mold and the glass material are heated, the core is placed in a retracted position and the mold body and the other of the mold main body are placed in a retracted position. The mold is closed by a mold opening and closing device to perform initial press molding, and then the core portion is advanced by a core portion driving device while the mold main body and the other mold are closed to perform final press molding. 3. A method for forming a glass element using the apparatus for forming a glass element according to 1 or 2.