Glass molding machine and glass molding method

Abstract

A glass molding machine includes a shaping die, a temperature controller, a die assembling state, a glass molding stage and a die disassembling stage. The shaping die includes a first, second and body molds. The die assembling stage feeds a glass material to the first mold with the body mold being fitted to the exterior of the first mold. The die assembling stage fits the second mold to the body mold to assemble the shaping die. The glass molding stage heats and molds the glass material. The die disassembling stage removes the second mold from the body mold after the molding, to remove the molded glass product. The temperature controller provides a temperature difference so that a temperature of the body mold is higher than a temperature of the second mold in the die assembling stage and in the die disassembling stage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing an overall configuration of a glass molding machine according to an embodiment of the invention.

FIG. 2 is a front view of the machine in FIG. 1.

FIG. 3 is a schematic section view explaining operations of a die assembling/disassembling device.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Exemplary embodiments of the invention will be explained below in detail while referring appropriately to the drawings.

In the drawings to be referred to, FIG. 1 is a schematic plan view showing an overall configuration of a glass molding machine according to an embodiment of the invention, and FIG. 2 is a front view of the machine in FIG. 1.

In this embodiment, the case where an optical lens L as a glass product is manufactured by a glass molding machine 1 will be explained by way of example.

As shown in FIG. 1, the glass molding machine 1 according to the embodiment of the invention includes a molding machine main body 2 as a heating/molding machine, a die assembling/disassembling device 3 that assembles and disassembles (i) a lower mold D1 and a body mold D3 and (ii) an upper mold D2 (shaping die D, see FIG. 2), a shaping-die conveying device 4 that carries the shaping die D between the die assembling/disassembling device 3 and the molding machine main body 2, and a feeding/removing device 5 that feeds a glass material G (see FIG. 2) and removes a glass product.

Here, the feeding/removing device 5 is provided with a robot hand, for example. Also, a glass material feeding device that feeds the glass material G (see FIG. 2) and a glass product removing device that removes the molded optical lens L are integrated to constitute the single feeding/removing device 5. However, the feeding/removing device 5 is not limited to this configuration. The glass material feeding device and the glass product removing device may be constructed as individual devices, and may be placed in separate locations.

As shown in FIG. 1, the molding machine main body 2 has, for example, a loading/unloading stage ST0 that loads and unloads the shaping die D (see FIG. 2), a heating stage ST1 that heats the shaping die D and the glass material G (see FIG. 2) fed into a cavity of the shaping die D, pressurizing/molding stages ST2, ST3 that heat and mold the glass material G while applying pressure thereto, an slowly cooling stage ST4 that curing the glass material G while slowly cooling the glass material G, and a cooling stage ST5 that cools the glass material G naturally to a temperature at which a composition of the glass stables.

Also, the molding machine main body 2 molds the optical lens L (see FIG. 2) as the glass product from the glass material G (see FIG. 2), while forwarding the shaping die D that is put on a turntable 21 to the respective stages sequentially.

Next, steps performed in the respective stages will be explained briefly below.

The shaping die D is moved from the loading stage ST0 to the heating stage ST1 according to a movement of the turntable 21. In this heating stage ST1, a temperature of the shaping die D is increased rapidly by a heating unit 22 (see FIG. 2) to exceed the transition point (e.g., 620° C.) of the glass material G or more. In the pressurizing/molding stages ST2, ST3, the optical lens L is molded by a pressurizing device 23 (see FIG. 2) while the temperature of the shaping die D is kept at the transition point or more. In the slowly cooling stage ST4, the molding temperature is decreased gently to the vicinity of the transition point while the shaping die D is heated so that the molding temperature does not fall suddenly. Then, in the cooling stage ST5, the shaping die D is naturally cooled to the temperature at which a composition of the glass is stabilized. Then, the shaping die D is moved to the unloading stage ST0.

In this embodiment, the above stage configuration is employed. However, the invention is not limited to this configuration. The configuration may be changed in response to the material of the glass material G and a product shape. Also, in this embodiment, the turntable system is employed. However, the invention is not limited to this configuration. The linear moving system may be employed.

Also, in this embodiment, the loading/unloading stage ST0 for the shaping die D provided in the molding machine main body 2 is constructed as a common stage. However, the invention is not limited to this configuration. The loading stage and the unloading stage may be provided separately in an inlet side and an exit side, respectively.

Next, the shaping die D used in the glass molding machine 1 will be explained below.

As shown in FIG. 2, the shaping die D includes the lower mold D1 and the upper mold D2, which are assembled with facing each other, and the body mold D3 fitted to exteriors of the lower mold D1 and the upper mold D2 to position the lower mold D1 and the upper mold D2. Then, in a state where the shaping die D is closed, the lower mold D1, the upper mold D2 and the body mold D3 form the cavity and the optical lens L is heated and molded therein.

Also, the lower mold D1, the upper mold D2 and the body mold D3 constituting the body mold D3 are made of a hard metal for a precision mold as molding materials, and have substantially the same coefficient of linear expansion. Therefore, even if a temperature of the shaping die D is changed, the clearance can be maintained constant as it is so long as the lower mold D1, the upper mold D2, and the body mold D3 are held at the same temperature.

In this embodiment, the shaping die D is constructed by the lower mold D1, the upper mold D2, and the body mold D3, and also the body mold D3 is fixed on the lower mold D1 side. However, the invention is not limited to this configuration. The body mold D3 may be fixed on the upper mold D2 side. Also, in this embodiment, the body mold D3 is constructed as a separate body from the lower mold D1 and the upper mold D2. However, the invention is not limited to this configuration. The body mold D3 may be integrated with the lower mold D1 or the upper mold D2.

As shown in FIG. 2, the die assembling/disassembling device 3 is arranged on the outside of the loading/unloading stage ST0 of the molding machine main body 2 and is adjacent to the molding machine main body 2 with being arranged across the shaping-die conveying device 4 from the molding machine main body 2.

The die assembling/disassembling device 3 includes a mold table 31 on which the lower mold D1 is put on, a heating/temperature-retention device 32 which may serve as a heating/heat-retention device of a temperature controller and which are arranged so as to heat the body mold D3, and an elevating device 33 that can move up and down the upper mold D2 in the vertical direction.

Also, a lower clamping device 34 that clamps the lower mold D1 is arranged on the mold table 31, and an upper clamping device 35 that clamps the upper mold D2 is arranged on an elevating plate 33a of the elevating device 33.

A high frequency heating device of the non-contact high frequency induction heating system may be employed as an example of the heating/temperature-retention device 32. This high frequency heating device is suitable because it can heat directly the body mold D3 as a heated object. Of course, the heating/temperature-retention device is not limited to the high frequency heating device. A heat block, a lamp heating system, or the like may be employed.

Also, the heating/temperature-retention device is not limited to the heating device. A heat-retention device that uses a heat insulation material such as glass wool may be employed. For example, in a state where a heat still remained after the shaping die D passes through the cooling stage ST5 (FIG. 1), only the temperature of the lower mold D1 side may be retained while the upper mold D2 side is cooled naturally to thereby provide a temperature difference between the body mold D3 and the upper mold D2.

The elevating device 33 includes the elevating plate 33a to which the upper mold D2 is fitted, a motor 33b as a driving source that moves the elevating plate 33a up and down, and a feed screw mechanism 33c that converts a rotation force of the motor 33b into a reciprocating motion.

In this embodiment, the elevating device 33 is configured so that the upper mold D2 is moved up and down with respect to the lower mold D1 to taken out/put in the upper mold D2. However, the invention is not limited to this configuration. The elevating device 33 may be configured so that the lower mold D1 and the body mold D3 are moved up and down with respect to the upper mold D2 to taken out/put in the upper mold D2.

The shaping-die conveying device 4 includes, for example, a driving device (not shown) and a carrying guide. For example, a fluid cylinder such as an air cylinder is employed as the driving device. The shaping-die conveying device 4 may be constructed by providing a linear guiding mechanism to this fluid cylinder. However, the invention is not limited to this configuration. Also, a servo motor, or the like may be employed as the driving source, and the shaping-die conveying device 4 may be constructed by combining this servo motor with the ball screw and the linear guiding mechanism. In short, various modes of the shaping-die conveying device 4 may be employed adequately in response to the configurations of the loading/unloading stage ST0 and the die assembling/disassembling device 3.

Next, operations of the glass molding machine 1 according to the embodiment of the invention configured as above will be explained below with reference to FIG. 3 mainly. FIG. 3 is a schematic section view explaining operations of the die assembling/disassembling device.

In the glass molding machine 1 according to the embodiment of the invention, as shown in FIG. 1, the shaping die D is carried into the loading/unloading stage ST0 from the die assembling/disassembling device 3. Then, when the turntable 21 is turned in the turning direction R, the shaping die D is transferred in sequence from the heating stage ST1 to the pressurizing/molding stages ST2, ST3, the slowly cooling stage ST4, and the cooling stage ST5. As a result, the optical lens L is molded. Thus, the shaping die D circulates through the respective stages ST0 to ST5, and again reaches the loading/unloading stage ST0.

When the shaping die D reaches the loading/unloading stage ST0 through the respective stages ST0 to ST5, the lower mold D1, the body mold D3 and the upper mold D2 are closed as shown in FIG. 2, and the optical lens L is molded in the closed cavity. Then, the shaping die D that has reached the loading/unloading stage ST0 in this manner is conveyed to the die assembling/disassembling unit 3 by the shaping-die conveying device 4.

As shown in FIG. 3A, when the shaping die D is conveyed to the die assembling/disassembling device 3, the shaping die D is fixed in a predetermined position of the mold table 31 while the lower mold D1 is being clamped by the lower clamping device 34 with the molds being closed. Here, in a state where the shaping die D is closed, the clearance between the upper mold D2 and the body mold D3 is set to the minimum (for example, about 0.5 to 2 μm) in order to increase a molding accuracy.

Then, as shown in FIG. 3B, when the optical lens L is to be removed from the mold by pulling the upper mold D2 off the body mold D3, the heating/temperature-retention device 32 is operated to heat the body mold D3 so that a temperature of the body mold D3 is increased higher than a temperature of the upper mold D2, to thereby provide a temperature difference (temperature gradient) therebetween.

Specifically, the temperature difference between the upper mold D2 and the body mold D3 is set to about 200° C., for example. The upper mold D2 can be removed smoothly if a temperature difference is set a range of 150° C. to 250° C. For example, even if such a strict molding accuracy is required that the clearance of the shaping die D should be set to 0.5 μm, the following relation is established so long as the temperature difference is set to 150° C. It is assumed that a coefficient of linear expansion of the molding material is α=5.2×10⁻⁶ and that an inner diameter of the body mold D3 is 10 mm. A total clearance (δ) can be given as

$\begin{array}{c}\delta =0.5+5.2\times {10}^{-6}\times 150\times 10\times {10}^3\\ =8.3\left[\mathrm{\mu m}\right]\end{array}$

Similarly, if the temperature difference is set to 250° C., a total clearance (δ) can be given as

$\begin{array}{c}\delta =0.5+5.2\times {10}^{-6}\times 250\times 10\times {10}^3\\ =13.5\left[\mathrm{\mu m}\right]\end{array}$

As a result, the necessary clearance can be ensured.

In this manner, the upper mold D2 is clamped by the upper clamping device 35 and then lifted upward by the elevating device 33 under the condition that the temperature difference (including a temperature gradient) is provided by heating the body mold D3 so that the temperature of the body mold D3 is set higher than the temperature of the upper mold D2. Thereby, the upper mold D2 can be removed smoothly from the body mold D3 (see FIG. 3C).

That is, according to the glass molding machine 1 according to this embodiment, the heating/temperature-retention device 32 is provided in the die assembling/disassembling device 3 to provide the temperature difference so that the temperature of the body mold D3 is set higher than the temperature of the upper mold D2. Thus, the inner diameter of the body mold D3 as a hole side becomes larger than the outer diameter of the upper mold D2 as a core side due to a thermal expansion caused by this temperature difference. Therefore, the clearance between the body mold D3 and the upper mold D2 can be expanded.

As a result, not only a molding accuracy can be ensured by keeping a predetermined minimum clearance at a time of molding, but also the die assembling/disassembling operations can be carried out smoothly by expanding the clearance at a time of assembling/disassembling the mold.

Here, a timing at which the upper mold D2 is lifted up by the elevating device 33 becomes an issue. However, this timing giving the clearance through which the upper mold D2 is removed smoothly can be determined based on molding trials that are carried out in advance. Also, the upper mold D2 may be removed by heating the body mold D3 while the elevating device 33 applies a predetermined pull-out force in a direction along which the upper mold D2 is remove to such an extent that the sliding face is not engaged.

Then, the molded optical lens L is removed by the feeding/removing device 5 in a state where the upper mold D2 is removed (see FIG. 3D). Then, the glass material G for the subsequent molding is fed to the lower mold D1 by the feeding/removing device 5 (see FIG. 3E).

In this manner, according to the glass molding machine 1 of this embodiment, the glass material G is fed to the lower mold D1 and then the body mold D3 fitted to this lower mold D1 is heated. Therefore, a heat shock of the glass material G can be lessened by warming the lower mold D1 side to which the glass material G is fed.

Then, in a condition that the temperature difference (temperature gradient) is provided by heating the body mold D3 so that the temperature of the body mold D3 is set higher than the temperature of the upper mold D2, the elevating device 33 puts down the upper mold D2 to insert it into the body mold D3 to perform the die assembling (see FIG. 3F).

Next, a glass molding method according to the embodiment of the invention will be explained below with reference to FIGS. 2 and 3 mainly. In the following explanation, the same reference symbols are affixed to the configurations that are common to those in the glass molding machine 1, and therefore redundant explanations will be omitted herein.

A glass molding method according to the embodiment of the invention heats and molds a glass product L from a glass material G with using a shaping die D. The shaping die D includes a lower mold D1, an upper mold D2 and a body mold D3. The lower and upper molds D1, D2 are to be assembled with facing each other. The body mold D3 is to be fitted to exteriors of the lower and upper molds D1, D2 to position the lower and upper D1, D2. The method includes a die assembling step that feeds the glass material G to the lower mold D1 with the body mold D3 being fitted to the exterior of the lower mold D1 and fits the upper mold D2 into the body mold D3 to assemble the shaping die D; a glass molding step that heats and molds the glass material G; and a die disassembling step that removes the upper mold D2 from the body mold D3 after the molding, to remove the molded glass product G. In the assembling and disassembling steps, the assembling and the removing include providing a temperature difference so that a temperature of the body mold D3 is higher than a temperature of the upper mold D2.

As shown in FIGS. 3A to 3C, the die disassembling step is a step in which the upper mold D2 is removed smoothly from the body mold D3 by clamping the upper mold D2 by the upper clamping device 35 and lifting up it by the elevating device 33 in a condition that the body mold D3 is heated to provide a temperature difference (temperature gradient) so that a temperature of the body mold D3 is increased higher than a temperature of the upper mold D2.

As shown in FIG. 1, the glass molding step is a step that molds the optical lens L by the loading/unloading stage ST0 that loads/unloads the shaping die D (see FIG. 2), the heating stage ST1 that heats the shaping die D and the glass material G (see FIG. 2) fed into the cavity in the shaping die D, the pressurizing/molding stages ST2, ST3 that heat/mold the glass material G while pressurizing it, the slowly cooling stage ST4 that cures the glass material G while cooling it gradually, and the cooling stage ST5 that naturally cools a composition of the glass so as to stabilize it.

As shown in FIGS. 3E and 3F, the die assembling step is a step in which the glass material G is fed to the lower mold D1 by the feeding/removing device 5, and then the upper mold D2 is put down by the elevating device 33 and is pushed into the body mold D3 to perform the die assembling in a condition that the temperature difference (temperature gradient) is provided by heating the body mold D3 so that the temperature of the body mold D3 is set higher than the temperature of the upper mold D2.

The exemplary embodiments of the invention have been explained in detail with reference to the drawings as above. However, the invention is not limited to such embodiments, and the invention may be modified appropriately within a scope that does not depart from a gist of the invention.

For example, in this embodiment, the heating/retaining unit 32 which may serve as the heating/heat-retention device and which heats the body mold D3 is employed as the temperature controller. However, the invention is not limited to this configuration. A cooling device that cools the upper mold D2 by using a nitrogen gas or the like may be provided. Also, both the heating/temperature-retention device 32 that heats the body mold D3 and the cooling device that cools the upper mold D2 may be provided.

Also, in this embodiment, the body mold D3 is heated directly by the heating/temperature-retention device 32. However, the invention is not limited to this configuration. For example, the body mold D3 may be heated indirectly by heating the lower mold D1 by means of a hot plate in which a heater is built. According to such configuration, the influence of a shape and a size of the shaping die D can be reduced, and the body mold D3 can be heated with a simple configuration even when multiple products are molded simultaneously.

Also, in this embodiment, the timing giving the clearance through which the upper mold D2 can be lifted up by the elevating device 33 and the upper mold D2 can be removed smoothly is determined based on the molding trials that are carried out in advance. However, the invention is not limited to this configuration.

For example, a temperature sensor for sensing temperatures of the upper mold D2 and the body mold D3, which are to be fitted to each other may be provided to the die assembling/disassembling device 3. Then, the temperature of the upper mold D2 may be increased by sensing a temperature by means of this temperature sensor.

Also, a temperature adjusting device that adjusting a temperature difference by controlling the temperature controller based on a molding temperature sensed by the temperature sensor may be provided to manage a temperature difference.

Claims

1. A glass molding machine comprising: a shaping die comprising a first mold,a second mold, the first and second molds to be assembled with facing each other, anda body mold that is to be fitted to exteriors of the first and second molds to position the first and second molds, the glass molding machine that heats and molds a glass product from a glass material by using the shaping die;a temperature controller;a die assembling stage that feeds the glass material to the first mold with the body mold being fitted to the exterior of the first mold, the die assembling stage that fits the second mold to the body mold to assemble the shaping die;a glass molding stage that heats and molds the glass material; anda die disassembling stage that removes the second mold from the body mold after the molding, to remove the molded glass product, wherein:the temperature controller provides a temperature difference so that a temperature of the body mold is higher than a temperature of the second mold in the die assembling stage and in the die disassembling stage.

2. The glass molding machine according to claim 1, wherein the first mold, the second mold and the body mold are formed of a molding material having a substantially identical coefficient of linear expansion.

3. The glass molding machine according to claim 1, wherein the temperature controller comprises a heating/heat-retention device that heats the body mold or keeps the temperature of the body mold.

4. The glass molding machine according to claim 1, wherein the temperature controller comprises a cooling device that cools the second mold.

5. The glass molding machine according to claim 1, wherein: the first mold is a lower mold, andthe second mold is an upper mold.

6. A glass molding machine comprising: a shaping die comprising a first mold,a second mold, the first and second molds to be assembled with facing each other, anda body mold that is to be fitted to exteriors of the first and second molds to position the first and second molds, the glass molding machine that heats and molds a glass product from a glass material by using the shaping die;a glass material feeding device that feeds the glass material to the first mold with the body mold being fitted to the exterior of the first mold;a die assembling device that fits the second mold to the body mold to assemble the shaping die;a heating/molding device that heats and molds the glass material using the shaping die assembled by the die assembling device;a die disassembling device that removes the second mold from the body mold after the heating/molding device heats and molds, to disassemble the shaping die;a glass product removing device that removes the glass product from the first mold and the body mold from which the second mold is removed; anda shaping-die conveying device that carries the shaping die between (i) the die assembling device and the die disassembling device and (ii) the heating/molding device, wherein:the die assembling device and the die disassembling device comprise a temperature controller that provides a temperature difference so that a temperature of the body mold is higher than a temperature of the second mold.

7. A glass molding method of heating and molding a glass product from a glass material with using a shaping die comprising a first mold,a second mold, the first and second molds to be assembled with facing each other, anda body mold that is to be fitted to exteriors of the first and second molds to position the first and second molds,

8. The glass molding method according to claim 7, wherein the providing of the temperature difference comprises heating the body mold or keeping the temperature of the body mold.

9. The glass molding method according to claim 7, wherein the providing of the temperature difference comprises cooling the body mold.

10. The glass molding method according to claim 7, wherein: the glass product is an optical element, andthe temperature difference is in a range of 150° C. to 250° C.

11. The glass molding method according to claim 7, wherein: the first mold is a lower mold, andthe second mold is an upper mold.