JPH0710568A - Extrusion molding method for polarizing glass and extrusion molding device - Google Patents

Abstract

PURPOSE:To rapidly and inexpensively obtain molded products of polarizing glass by producing gaseous flow in a region where heated moldings pass and controlling this gaseous flow to form a temp. gradient for cooling and solidifying, thereby cooling and solidifying glass while preventing the respheroidization of polarizing particles and the failure of the glass and while maintaining the orientation state of the polarizing particles. CONSTITUTION:A die 4 provided with a nozzle 4a having a desired sectional shape is mounted in a container 5 and is housed in a housing 2. A billet 6 of raw material glass to be molded is installed in the container 5 and a punch 7 is placed thereon. A temp. controller (not shown in Fig.) is set at a desired temp. (e.g. 610 deg.C) and band heaters 8, 9, 10 are energized. A cooling gas (e.g.: gaseous nitrogen) is controlled to a desired flow rate: e.g.: 20ml per minute) by using a constant flow rate valve (not shown in Fig.) and is fed into an air feed pipe 12. A hydraulic device (not shown in Fig.) is set at desired load (e.g.: 760kg/cm<2>) and extrusion is started by applying load to a punch 7. The raw material softened by heating is extruded from the nozzle 4a and is cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion molding method of polarizing glass for producing a polarizing glass used in a micro optical isolator used in the field of optical communication and the like, and an extrusion molding apparatus used in this method. .

[0002]

2. Description of the Related Art For example, a method using an extrusion molding method has been conventionally known as a method for producing a polarizing glass used for a micro optical isolator used in the field of optical communication and the like (for example, See Japanese Patent Publication No. 63-63499).

This method utilizes a usual extrusion molding method, and in addition to the usual purpose of molding a glass into a desired shape, it is included in a raw material glass for forming a polarizing property. It also has the purpose of stretching spherical particles (polarizing particles) made of CuCl or the like and orienting them in one direction.

Further, the extrusion molding apparatus used for carrying out this method is roughly classified into a forward extrusion system for extruding the molding raw material in the same direction as the advancing direction of the pressure tool which is an extruding means for extruding the molding raw material. There is a backward extrusion method in which the forming raw material is extruded in a direction opposite to the traveling direction of the pressure tool, but the forward extrusion method is generally used.

FIG. 7 is a sectional view showing a schematic structure of a conventional extrusion molding apparatus. In FIG. 7, a billet 60 as a forming raw material is heated and softened in a container 50 as a forming raw material accommodating portion to a viscosity capable of being extruded by a heater (not shown) or the like, and a load is applied to a punch 70 as an extruding means from above. Nozzle of extrusion die barrel 40 (extrusion port)
Is pushed out from. The molding raw material is flowed out from the nozzle of the die 40 and molded, and then naturally cooled according to a temperature gradient peculiar to the apparatus or, if necessary, gradually cooled by passing through a heat retaining device.

[0006]

By the way, in order to obtain a polarizing glass by using the above-mentioned conventional extrusion molding apparatus, when the molding raw material containing the polarizing particles is extruded from the extrusion port, the polarizing particles are stretched. It is necessary to orient it in the direction and solidify by cooling while maintaining that state.

However, when the stretched polarizing particles are kept at a high temperature even after being extruded, they tend to re-spheroidize to return to their original shape. The re-sphericalization rate becomes higher as the temperature becomes higher than the strain point of glass. The glass including the re-sphericalized polarizing particles has a significantly deteriorated polarizing property. When a conventional extrusion molding apparatus is used, the glass extruded from the die may be exposed to a high temperature for a sufficient time for the polarized particles to be re-spheroidized.

Therefore, the above-mentioned Japanese Patent Publication No. 63-63499 discloses a method in which extrusion is carried out at a temperature as low as possible so that the speed of re-spheroidization is extremely slowed, and a glass extruded from a die is cooled with a cooling liquid. It describes how to use it to cool quickly. However, the former method requires a very high pressure for extrusion, which requires a large apparatus and has a drawback that the extrusion speed is very slow and the productivity is low. In the latter method, since the cooling liquid having a large heat capacity and a high heat transfer coefficient is brought into direct contact with the high temperature glass immediately after being extruded, the glass may be broken if the temperature difference between the two is more than a predetermined value. It is expensive, and in order to avoid this, a temperature control mechanism that precisely controls the cooling liquid to a predetermined temperature is required. Furthermore, a cooling liquid supply mechanism and a recovery mechanism are also required, which makes the device significantly complicated. There is.

The present invention has been made under the background described above, and provides an extrusion molding method and an extrusion molding apparatus for polarizing glass, which enables extrusion molding of polarizing glass with a relatively simple structure. This is the purpose.

[0010]

In order to solve the above-mentioned problems, an extrusion molding method for polarizing glass according to the present invention comprises: (Structure 1) A polarizing glass containing polarizing particles heated to a temperature at which extrusion molding is possible. A molding material is extruded from a polarizing glass, which is obtained by extruding from a extrusion port of an extrusion mold and then cooling and solidifying to obtain a molded product of polarizing glass in which the polarizing particles contained in the molding material are stretched and oriented in one direction. In the method, for forming a gas flow in a region through which the heated molding extruded from the extrusion port passes, and controlling the gas flow to cool and solidify the heated molding in the region through which the heated molding passes. By forming a temperature gradient, the heated molded product is cooled and solidified while maintaining the orientation state of the polarized particles in the heated molded product extruded from the extrusion port to obtain a molded product of polarizing glass. In addition, the extrusion molding apparatus according to the present invention is configured as follows: (Structure 2) A molding raw material storage part and a molding raw material that is connected to the molding raw material storage part and stored in the molding raw material storage part are extruded and molded. An extrusion molding die having an extrusion port for heating, a heating means for heating the molding raw material stored in the molding raw material accommodating portion, and a molding raw material accommodated in the molding raw material accommodating portion is extruded from the extrusion opening of the extrusion molding die. In the extrusion molding apparatus provided with a molding raw material extrusion means for forming a gas flow for forming a temperature gradient for cooling the heating molding in a region through which the heating molding extruded from the extrusion port of the extrusion molding mold passes. The gas flow forming means for generating is provided.

[0011]

According to the above configuration 1, a gas flow is formed in a region through which the heated molded product extruded from the extrusion port of the extrusion mold passes, and the gas flow is controlled so that the heated molded product passes through the region. Since a temperature gradient for cooling and solidifying the heat-molded product is formed, a relatively simple structure prevents re-spheroidization of the polarizing particles and at the same time prevents the glass from being broken, and from the extrusion port. It has become possible to obtain a molded product of polarizing glass by cooling and solidifying the heated molded product while maintaining the oriented state of the polarizing particles in the extruded heated molded product.

That is, the heat-molded product extruded from the extrusion port of the extrusion mold contacts the gas flow and is cooled when passing through the region where the gas flow is formed. In that case, the gas has a significantly smaller heat capacity and a smaller heat transfer coefficient than liquid refrigerants, etc. The risk of breakage can be significantly reduced, and a sufficient cooling effect can be obtained to obtain the effect of preventing re-sphericalization. Furthermore, since the formation of the gas flow can be controlled by, for example, selecting the direction of ejection from the ejection nozzle or the ejection flow rate or flow velocity thereof, it is significantly easier to control as compared with a liquid, so that an optimal temperature gradient for cooling and solidification can be obtained. It is also easy to form. Further, the gas is not necessarily required to be recovered like the liquid, and hence it is easy to handle. Therefore, the device for forming the gas flow can also be configured by a relatively simple device such as a jet nozzle or a flow rate adjusting valve.

Further, at this time, since it is not necessary to cool the extrusion molding die itself, a sufficient extrusion speed can be secured, and an apparatus for cooling the extrusion molding die is not necessary.

Further, according to the constitution 2, it is possible to obtain an extrusion molding apparatus which can carry out the method of the constitution 1.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a sectional view of a main part of an extrusion molding apparatus according to a first embodiment of the present invention. Hereinafter, referring to FIG. 1, the first
An extrusion molding apparatus according to an embodiment will be described, and then an example in which the extrusion molding method for polarizing glass according to the present invention is performed using the extrusion molding apparatus will be described.

In FIG. 1, reference numeral 1 is a pedestal. A cylindrical housing 2 is fixed on the pedestal 1, and a support cylinder 3 is installed in the housing 2 so as to ride on the pedestal 1. A ceiling portion 3b having a through hole 3a in the central portion is formed at the upper end portion of the support cylinder 3, and a die 4 is installed on the ceiling portion 3b.

The die 4 has a cylindrical shape with a step and a cross section of a substantially convex shape, and the nozzle 4 extends along the central axis.
a is formed. A cylindrical container 5 is fitted and installed in the small diameter portion of the die 4. This container 5
A glass billet 6 serving as an extrusion molding raw material is housed therein, and a punch 7 for applying pressure to the billet 6 is housed therein.
Is installed. Band heaters 8, 9 and 10 for heating the billet 6 are attached to the outside of the housing 2 and are driven by a temperature adjusting device (not shown).

A gas flow forming device 11 is installed inside the support cylinder 3 and immediately below the ceiling portion 3b.
2 is a sectional view of the gas flow forming apparatus of the first embodiment, and FIG. 3 is a bottom view of the gas flow forming apparatus of the first embodiment. As shown in these drawings, the gas flow forming device 11 has a gas passage 11a inside the ring, and is connected to two gas introduction ports 11b for introducing gas into the gas passage 11a. The cooling gas supplied through the trachea 12 penetrates toward the inclined surface portion 11c below the inner peripheral surface of the ring 11 to form a plurality of ejection ports 11.
The gas is ejected from d to form a downward airflow inside the support cylinder 3, and an optimum temperature gradient is formed for cooling the hot molded glass 6a extruded by the die 4. The gas flow forming device 11 is installed by fixing the air supply pipe 12 to the pedestal 12 by the fixing plate 13. Although not shown, the gas supply pipe 12 is supplied with a cooling gas (a nitrogen gas in this embodiment) whose flow rate is controlled from a high-pressure gas cylinder or the like through a constant flow valve or the like.

Next, an operation procedure for carrying out extrusion molding with the above-mentioned apparatus will be described.

The initial state of this apparatus is a state in which the die 4, the container 5, the billet 6 and the punch 7 are removed. First, a die 6 having a nozzle 4a having a desired cross-sectional shape (circular in this embodiment) is attached to the container 5,
Put it in the housing 2. Next, the billet 6 of the forming raw material glass is placed in the container 5, and the punch 7 is placed thereon.
Put on. Next, a temperature controller (not shown) is set to a desired temperature (610 ° C. in this embodiment), and the band heaters 8, 9 and 10 are energized. Next, the cooling gas (nitrogen gas in this embodiment) is controlled to a desired flow rate (20 milliliters per minute in this embodiment) using a constant flow valve (not shown), and is fed into the air supply pipe 12. Wait until the temperature reaches the set value and stabilizes. Thereafter, a hydraulic device (not shown) is loaded with a desired load (760 Kg / cm ² in this embodiment).
Then, the punch 7 is loaded to start extrusion.
The heated and softened forming raw material glass is extruded from the nozzle 4a of the die 4 and then rapidly cooled in accordance with a controlled temperature gradient therebelow.

Next, an example of manufacturing a polarizing glass using the above-mentioned extrusion molding apparatus will be described.

First, 60.0 wt% of SiO ₂ and AlF
₃ is 2.0 wt%, Al ₂ O ₃ is 6.0 wt%, B ₂ O
₃ is 20.0 wt%, CuCl is 0.9 wt%, NaC
l is 1.0 wt%, Na ₂ O is 10.0 wt%, SnO
Glass having a composition of 0.1 wt% was melted in a 3-liter platinum crucible at about 1450 ° C., poured into a graphite mold, molded, and gradually cooled to room temperature. Heat treatment for 120 minutes at about 16 grains
CuCl particles of 0 nm were deposited.

Next, this is 50 mm in diameter and 25 mm in length.
It was cut into a billet 6 and installed in the container 5 of the extrusion molding apparatus. As the die 4, a die having a nozzle 4a having a circular sectional shape with a diameter of 5 mm was used. In this case, a diameter of about 5.5 mm is provided just below the nozzle 4a.
The guide 14 having the through-holes is arranged.

The gas flow forming device 11 has a nozzle 11d at a position 80 mm below the nozzle 4a of the die 4.
Was placed so that In this case, spout 11d
6 was formed on the slope 11c at substantially equal intervals, and the inner diameter was 1 mm and the ejection direction was 45 ° with respect to the vertical direction.

Next, the forming raw material glass in the container 5 is heated to 610 ° C., which is a temperature at which the viscosity becomes about 1 × 10 ⁹ poise, and 20 milliliters / minute of nitrogen gas is flown from the gas flow forming device 11. Was extruded under a load of 760 kg / cm ² .

FIG. 4 is a graph showing the temperature distribution from the upper end of the die to the lower part. In FIG. 4, the vertical axis represents the temperature, the horizontal axis represents the distance from the upper end of the die, and the curve shown by the solid line is the case of the above embodiment in which the gas flow is formed by the gas flow forming device, and the broken line. The curve indicated by is when the gas flow is not formed. According to the solid line curve of FIG. 4, this glass flow formation causes the annealing point (about 5 mm) of the glass at about 50 mm downward from the upper end of the nozzle 4a.
The temperature has dropped to around (00 ° C). Since the extrusion speed at this time was about 2.5 mm / sec, it means that it passed through the guide 14 after about 5 seconds after leaving the lower end portion thereof, which was sufficient to prevent re-sphericalization. On the other hand, according to the broken line curve of FIG. 4, when the gas flow is not formed, the glass is not cooled near the gradual cooling point (about 500 ° C.) until it reaches about 125 mm below the upper end of the nozzle 4a. At a temperature of 100 ° C. and the extruded glass will be exposed to the hot space for about 35 seconds. Therefore, the possibility of re-sphericalization becomes extremely high.

The above extrusion process thus resulting molded glass is about 1000 × without CuCl particles respheriodize
It was confirmed by observation with a transmission electron microscope that the particles were deformed into a shape of 30 nm (aspect ratio 33: 1) and were oriented in almost one direction. This molded glass was polished to a thickness of 1 mm and then reduced in a hydrogen atmosphere at 425 ° C. for 4 hours to obtain an extinction ratio of 50 d at a wavelength of 1.31 μm.
b, a polarizing glass exhibiting 51 db at a wavelength of 1.55 μm could be obtained.

According to the above-mentioned embodiment, a molded glass can be obtained with a relatively simple structure while preventing re-spheroidization of the polarizing particles and at the same time preventing the glass from being damaged, resulting in quenching. It has become possible to quickly and inexpensively and easily obtain a polarizing glass having an excellent ratio.

That is, even if extrusion is performed at a high temperature, re-spheroidization of the polarizing particles can be prevented without causing damage to the glass due to temperature impact by controlling the temperature gradient below the die, so that the polarizing particles having a high aspect ratio can be prevented. It is possible to produce a polarizing glass having a high extinction ratio in the infrared region including a high extrusion rate. Also, the device for that purpose has a simple structure and is easy to handle. Further, since the temperature range that can be used for extrusion is widened, the aspect ratio of the polarizing particles can be easily controlled, and the polarizing glass exhibiting the highest extinction ratio at a desired wavelength can be easily manufactured.

Second Embodiment In this embodiment, as the die 4, a nozzle 4a having a rectangular shape of 2.5 mm × 12.5 mm is used, and the first embodiment has an annular shape. Since it is almost the same as the first embodiment except that a gas flow forming device 21 having a square ring shape is used instead of the gas flow forming device 11 in FIG. The same reference numerals are given and the description thereof is omitted, and hereinafter, the gas flow forming device 21 will be mainly described.

FIG. 5 is a sectional view of the gas flow forming apparatus of the second embodiment, and FIG. 6 is a bottom view of the gas flow forming apparatus of the second embodiment. As shown in these drawings, the gas flow forming device 21 has a gas passage 21a inside a square ring, and two gas introduction ports 2 for introducing gas into the gas passage 21a.
The cooling gas supplied through the air supply pipe 12 connected to 1b is supplied to the pair of facing slope portions 21c at the lower portion of the inner peripheral surface of the square ring.
About 4 downwards from the four jet outlets 11d ₁ and 11d ₂ penetrating toward ₁ and 21c ₂ in the vertical direction.
It is jetted in a direction of 5 ° to form a downward airflow inside the support cylinder 3 to form an optimum temperature gradient for cooling the hot molded glass 6a extruded by the die 4. The other structure is almost the same as that of the first embodiment.

Next, an example of manufacturing a polarizing glass using this apparatus will be described.

First, a glass containing CuCl particles having a particle diameter of 160 nm prepared in the same manner as in the first embodiment was used to obtain a glass having a diameter of 50 m.
It was cut into a billet 6 having a length of 25 mm and a length of 25 mm, and the billet 6 was set in the above-described extrusion molding apparatus and extrusion molding was performed under the same extrusion conditions as in the first example.

The molded glass obtained by this extrusion molding had CuCl particles of about 800 × 50 nm without re-sphericalization.
It was confirmed by transmission electron microscope observation that they were transformed into a shape of (aspect ratio 16: 1) and were oriented in almost one direction. After polishing this glass to a thickness of 1 mm,
By performing reduction treatment in a hydrogen atmosphere at 425 ° C. for 4 hours, the extinction ratio was 46 dB at a wavelength of 1.31 μm and a wavelength of 1.
A polarizing glass exhibiting 40 db at 55 μm could be obtained.

Also in this embodiment, the same advantages as in the first embodiment can be obtained.

In each of the above-mentioned embodiments, the presently used main extrusion type molding apparatus is used, but it goes without saying that the present invention can be applied to a rear extrusion type molding apparatus. Further, in this case, the shape of the gas flow forming device, the shape of the ejection port and other conditions are not limited to those shown in the embodiment, and depending on the purpose, for example, the ejection port may have a slit shape. Of course, it can be appropriately modified. further,
The composition of the glass is not limited to that shown in each example.

[0037]

As described above, the method for manufacturing a polarizing glass and the extrusion molding apparatus according to the present invention form a gas flow in a region through which a heat-molded product extruded from an extrusion port of an extrusion mold passes. Since the temperature gradient for cooling and solidifying the heat-molded product is formed in the region where the heat-molded product passes by controlling the gas flow, the re-sphericalization of the polarizing particles is prevented by the relatively simple structure. At the same time, while preventing the possibility of damaging the glass, while maintaining the orientation state of the polarizing particles in the heat-molded product extruded from the extrusion port, the heat-molded product is cooled and solidified to quickly and inexpensively form a polarized glass molded product. It is what made it possible to obtain.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of an extrusion molding apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the gas flow forming device according to the first embodiment.

FIG. 3 is a bottom view of the gas flow forming device according to the first embodiment.

FIG. 4 is a graph showing a temperature distribution from the upper end of the die to the lower side.

FIG. 5 is a sectional view of a gas flow forming device according to a second embodiment.

FIG. 6 is a bottom view of the gas flow forming device according to the second embodiment.

FIG. 7 is a cross-sectional view showing a schematic configuration of a conventional extrusion molding apparatus.

[Explanation of symbols]

1 ... Pedestal, 2 ... Housing, 3 ... Support tube, 4 ... Dice,
4a ... Nozzle, 5 ... Container, 6 ... Billet, 7 ... Punch, 8, 9, 10 ... Band heater, 11, 21 ... Gas flow forming device, 12 ... Air pipe.

Claims (2)

[Claims] 1. A polarizing particle contained in the molding raw material, which is obtained by extruding a polarizing glass molding raw material containing polarizing particles heated to a temperature capable of extrusion molding from an extrusion port of an extrusion mold and then cooling and solidifying the raw material. In the extrusion method of polarizing glass to obtain a molded article of polarizing glass which is stretched and is oriented in one direction, a gas flow is formed in a region where a heated molded article extruded from the extrusion port passes, and the gas flow is By controlling to form a temperature gradient for cooling and solidifying the heat-molded product in a region where the heat-molded product passes, the orientation state of the polarizing particles in the heat-molded product extruded from the extrusion port is maintained. An extrusion molding method for polarizing glass, characterized in that a molded article of polarizing glass is obtained by cooling and solidifying the heated molded article. 2. A molding raw material storage part, an extrusion mold having an extrusion port coupled to the molding raw material storage part for extruding and molding the molding raw material stored in the molding raw material storage part, and the molding raw material storage part. In an extrusion molding apparatus comprising a heating means for heating the molding raw material stored in, and a molding raw material extruding means for extruding the molding raw material stored in the molding raw material storage part from the extrusion port of the extrusion molding die, A gas flow forming means for generating a gas flow for forming a temperature gradient for cooling the heated molded product is provided in a region where the heated molded product extruded from the extrusion port of the extrusion mold passes. Extrusion molding equipment.