Glass base material hanging mechanism

Abstract

Provided is a glass base material hanging mechanism that, when hanging a starting member or a glass base material, can tightly (solidly) connect the hanging shaft tube and the hanging component and can vertically align the hanging component and the center of the glass base material.

Claims

1. A glass base material hanging mechanism that is used in an optical fiber glass base material manufacturing apparatus or an optical fiber drawing apparatus, the glass base material hanging mechanism comprising: a hanging shaft tube that is for hanging a starting member or glass base material and that has a horizontal hole formed in a side portion thereof passing through a central axis thereof; and a hanging component that is positioned above the starting member or glass base material and that has a horizontal hole with an inclined flat surface, wherein the flat surface is formed in a top surface of the horizontal hole in a manner to be inclined relative to a horizontal plane in a cross-sectional plane orthogonal to a direction in which the horizontal hole extends, the hanging component is inserted into the hanging shaft tube, both of the horizontal holes are aligned and a hanging pin is inserted through the horizontal holes to connect the hanging shaft tube and the hanging component such that a side surface of the hanging component is in contact with an inner surface of the hanging shaft tube, and a vertical hole center of the hanging shaft tube is provided at a position offset from an outer diameter center of the hanging shaft tube.

2. The glass base material hanging mechanism according to claim 1, wherein the hanging pin is a cylindrical pillar having a flat surface formed in a portion of a side surface thereof, and the flat surface of the hanging pin is connected to and in contact with the flat surface of the horizontal hole of the hanging component.

3. The glass base material hanging mechanism according to claim 1, wherein the horizontal hole of the hanging component is formed by inserting into a round hole a flat surface forming member having the inclined flat surface.

4. The glass base material hanging mechanism according to claim 1, wherein an angle formed between the horizontal plane and the inclined flat surface in the horizontal hole of the hanging component is no less than 20 degrees and no greater than 60 degrees.

5. A glass base material hanging mechanism that is used in an optical fiber glass base material manufacturing apparatus or an optical fiber drawing apparatus, the glass base material hanging mechanism comprising: a hanging shaft tube that is for hanging a starting member or glass base material and that has a horizontal hole formed in a side portion thereof passing through a central axis thereof; and a hanging component that is positioned above the starting member or glass base material and that has a horizontal hole with an inclined flat surface, wherein the flat surface is formed in a top surface of the horizontal hole in a manner to be inclined relative to a horizontal plane in a cross-sectional plane orthogonal to a direction in which the horizontal hole extends, the hanging component is inserted into the hanging shaft tube, both of the horizontal holes are aligned and a hanging pin is inserted through the horizontal holes to connect the hanging shaft tube and the hanging component, and a vertical hole center of the hanging shaft tube is provided at a position offset from an outer diameter center of the hanging shaft tube.

6. The glass base material hanging mechanism according to claim 5, wherein the vertical hole center of the hanging shaft tube is offset from a center of an outer contour of the hanging shaft tube in a direction opposite a lower side of the flat surface of the horizontal hole of the hanging component.

7. The glass base material hanging mechanism according to claim 1, wherein the optical fiber glass base material manufacturing apparatus is one of a porous glass base material deposition apparatus, a porous glass base material sintering apparatus, a glass base material elongating apparatus, and an optical fiber drawing apparatus.

8. A glass base material hanging method, comprising: in an optical fiber glass base material manufacturing apparatus or an optical fiber drawing apparatus, including a hanging shaft tube for hanging a starting member or glass base material, forming a horizontal hole in a side portion of the hanging shaft tube that passes through a central axis, including a hanging component that is positioned above the starting member or glass base material, forming a horizontal hole passing through a center line of the hanging component with an inclined flat surface in the hanging component, and forming the flat surface in a top surface of the horizontal hole in a manner to be inclined relative to a horizontal plane in a cross-sectional plane orthogonal to a direction in which the horizontal hole extends; inserting the hanging component into the hanging shaft tube; and aligning both horizontal holes and inserting a hanging pin through the horizontal holes to connect the hanging shaft tube and the hanging component such that a side surface of the hanging component is in contact with an inner surface of the hanging shaft tube; wherein a vertical hole center of the hanging shaft tube is provided at a position offset from an outer diameter center of the hanging shaft tube.

9. The glass base material hanging mechanism according to claim 1, wherein the inclined surface of the horizontal hole of the hanging component spans a center line of the hanging component.

10. The glass base material hanging method according to claim 8, wherein the inclined surface of the horizontal hole of the hanging component is formed to span the center line of the hanging component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic vertical cross-sectional view of the glass base material hanging mechanism of the present invention.

(2) FIG. 2 is a schematic view of an exemplary hanging component according to the present invention.

(3) FIG. 3 is a schematic view of an exemplary hanging shaft tube according to the present invention.

(4) FIG. 4 is a schematic view of an exemplary hanging pin according to the present invention.

(5) FIG. 5 is a schematic vertical cross-sectional view of a conventional glass base material hanging mechanism.

(6) FIG. 6 is a schematic vertical cross-sectional view of a conventional glass base material hanging mechanism.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) Hereinafter, an embodiment of the present invention will be described, but the embodiment does not limit the invention.

(8) A glass base material hanging mechanism includes a hanging shaft tube that is for hanging a starting member or glass base material and that has a horizontal hole formed in a side portion thereof passing through a central axis thereof, and a hanging component that is positioned above the starting member or glass base material, the hanging component having a horizontal hole with an inclined flat surface. The flat surface is formed in a top surface of the horizontal hole in a manner to be inclined relative to a horizontal plane in a cross-sectional plane orthogonal to a direction in which the horizontal hole extends, the hanging component is inserted into the hanging shaft tube, and both horizontal holes are aligned and a hanging pin is inserted through the horizontal holes to connect the hanging shaft tube and the hanging component.

(9) In this way, the flat surface formed within the horizontal hole of the hanging component is formed in the top surface of the horizontal hole in a manner to be inclined relative to a horizontal plane in a cross-sectional plane orthogonal to the direction in which the horizontal hole extends. As a result, when the hanging pin is inserted, the load placed on the hanging pin causes the hanging component to be pressed along the inner surface of the hanging shaft tube. Therefore, the vertical line passing through the center of mass of the glass base material passes through the center of the hanging pin, and so the hanging shaft tube and the hanging component can be tightly connected without tilting the glass base material.

(10) The hanging pin is a cylindrical pillar having a flat surface formed by removing a portion of a side surface thereof, and the flat surface of the hanging pin contacts the flat surface of the horizontal hole of the hanging component. In this way, the contact between the hanging pin and the hanging component changes from linear contact to surface contact, thereby reducing stress and preventing damage to the contacting portions. Furthermore, the inclined surface of the horizontal hole of the hanging component is preferably formed to span the center line of the hanging component. In this way, the surface area of the contact surface with the flat surface of the hanging pin can be increased, thereby reducing the pressure on the flat surface. As a result, small cuts that cause damage in the flat surface of the hanging pin and the hanging component are less likely to occur.

(11) The hanging component includes a circular hole in the side surface thereof, and the round hole preferably has therein a flat surface forming member that is a cylindrical pillar from which a portion of the side surface is removed to form a flat surface. The hanging component is made of the same quartz glass as the glass base material, and therefore complex machining of the hanging component requires significant effort and cost. By using this method, only the simple processes of machining the round hole in the side surface of the quartz glass rod and removing the portion to form the flat surface forming member from the quartz glass rod are necessary, and therefore the cost and effort can be decreased.

(12) The angle between the horizontal plane and the inclined flat surface formed in the horizontal hole of the hanging component is set within a prescribed range. The threshold values for the range of are set in consideration of two features, which are the pressing force exerted on the inner surface of the hanging shaft tube by the hanging component and the prevention of shrinkage fitting.

(13) If the force of friction is ignored, the pressing force exerted on the inner surface of the hanging shaft tube by the hanging component is expressed as W.Math.sin .Math.cos , with W representing the weight of the glass base material. When is less than 20 degrees or more than 70 degrees, the pressing force is weak, and a gap occurs between the inner wall of the hanging shaft tube and the inner surface of the hanging component. Accordingly, in order to achieve sufficient pressing force, is preferably set to always be no less than 20 degrees and no greater than 70 degrees.

(14) On the other hand, when is greater than 60 degrees, the heating and cooling cycle causes the hanging shaft tube, hanging component, or hanging pin to be damaged or causes the hanging pin to become stuck to the hanging shaft tube and hanging component. This phenomenon is referred to as shrinkage fitting. Shrinkage fitting occurs when the thermal expansion coefficient of the hanging shaft tube is greater than the thermal expansion coefficient of the hanging component. The hanging shaft tube that expands further due to the high temperature contracts when cooled, and presses on the hanging component positioned therein. This force is represented as F. This force causes the hanging component to press up on the inclined surface of the hanging pin, and the magnitude of this force is F.Math.cos . In contrast to this force, a gravitational force of W.Math.sin presses down on the inclined surface. Accordingly, the difference between these forces (F.Math.cos W.Math.sin ) is the magnitude of the force pressing up on the inclined surface. Accordingly, if F.Math.cos W.Math.sin is greater than 0, the hanging component is pressed by the contracting hanging shaft tube during cooling and moves within the hanging shaft tube, and therefore shrinkage fitting does not occur. Here, the magnitude of F is the result of natural forces and cannot be changed by people, and therefore an actual performance evaluation is difficult. Accordingly, values of that fulfill the above mathematical expression were sought experimentally. As a result, it was found that is preferably kept at 60 degrees or less.

(15) Based on the above, the range of is preferably no less than 20 degrees and no greater than 70 degrees when considering the pressing force exerted on the inner surface of the hanging shaft tube by the hanging component and no greater than 60 degrees when considering prevention of shrinkage fitting, and therefore is preferably no less than 20 degrees and no greater than 60 degrees when considering both of these characteristics.

(16) The ideal value for differs depending on the weight of the glass base material, the diameter of the hanging component, the material of the hanging shaft tube, and the like, but if the weight of the glass base material is from 80 kg to 150 kg, the diameter of the hanging component is 40 mm, and silicon nitride ceramic is used for the hanging shaft tube and the hanging pin, for example, then shrinkage fitting can be avoided and suitable pressing can be achieved by setting to be no less than 20 degrees and no more than 60 degrees.

(17) By sandwiching a shock absorbent material between contacting portions of the flat surfaces of the hanging pin and the horizontal hole of the hanging component, the occurrence of shrinkage fitting can be further reduced. The shock absorbent material should act as a heat resistant cushion, and suitable materials include an expandable graphite sheet, a C/C composite sheet, or a Teflon sheet (registered trademark), for example. In particular, due to the sintering, elongating, and drawing steps that use high temperatures, high temperature resistance and high staining resistance are desired characteristics, and therefore an expandable graphite sheet or a C/C composite sheet that has been highly purified can be used as needed.

(18) If the hanging component is tilted when the hanging shaft tube and the hanging component are combined, in order to align the center of the hanging component with the center of the hanging shaft tube, the center of the vertical hole of the hanging shaft tube, i.e. the insertion hole for the hanging component, can be offset from the outer diameter center of the hanging shaft tube in a direction opposite the lower side of the flat surface of the horizontal hole of the hanging component.

(19) Examples of apparatuses that can serve as the glass base material manufacturing apparatus of the present embodiment include a porous glass base material deposition apparatus, a porous glass base material sintering apparatus, a glass base material elongating apparatus, and an optical fiber drawing apparatus.

(20) The glass base material hanging apparatus of the present embodiment is described in further detail using FIGS. 1 to 4.

(21) FIG. 1 is a schematic view of an exemplary configuration of the glass base material hanging apparatus according to the present embodiment. FIG. 2 shows an exemplary glass base material hanging component according to the present embodiment.

(22) The horizontal hole 11 is formed in the hanging component 1, and the flat surface 12 is formed in the top surface of the horizontal hole 11 to be inclined at an angle from the horizontal plane within a cross-sectional plane that is orthogonal to the direction in which the horizontal hole 11 extends. In particular, in the present embodiment, the flat surface 12 is inclined at an angle from the horizontal plane within each cross-sectional plane orthogonal to the direction in which the horizontal hole 11 extends. In the present embodiment, the angle is 30 degrees. The flat surface 12 can be formed by connecting the flat surface forming member 13 to the top surface of the circular horizontal hole 11, and the means for connecting the flat surface forming member 13 can be selected from among a heat resistant ceramic adhesive, an epoxy adhesive, and double-sided tape, for example, depending on the temperature to be used and the desired staining resistance.

(23) FIG. 3 shows an exemplary hanging shaft tube of the present embodiment, and the horizontal hole 4 formed in the hanging shaft tube 3.

(24) In order to align the center of the hanging component 1 with the center of hanging shaft tube 3 when combining the hanging shaft tube 3 and the hanging component 1, the vertical hole center 14 of the hanging shaft tube 3 may be offset from the outer diameter center 15 of the hanging shaft tube 3 in a direction opposite the lower side of the flat surface 12 in the horizontal hole 11 of the hanging component 1.

(25) FIG. 4 shows an exemplary hanging pin according to the present embodiment. The hanging pin 5 may be a simple cylindrical pillar, but is preferably a cylindrical pillar from which a portion of the side surface is removed to form the flat surface 16, as shown in FIG. 4.

(26) The hanging component 1 is inserted into the vertical hole of the hanging shaft tube 3, and the hanging pin 5 is inserted into the horizontal hole 11 of the hanging component 1 and the horizontal hole 4 of the hanging shaft tube 3, thereby connecting the hanging component 1 and the hanging shaft tube 3. An expandable graphite sheet or the like may be sandwiched between the contact surfaces of the hanging pin 5 and the horizontal hole 11 of the hanging component 1, to serve as the shock absorbent material.

(27) In the manner described above, by hanging the hanging component 1 in the hanging shaft tube 3, the center of mass 6 of the glass base material is directly below the hanging pin 5, and therefore the glass base material does not tilt. Furthermore, due to the effect of the flat surface 12 provided on the top surface of the horizontal hole of the hanging component 1 at an inclined angle of 30 degrees relative to the horizontal plane, the hanging component 1 is tightly in contact with the inner surface of the hanging shaft tube 3 (the left side surface in FIG. 1), thereby tightly connecting the hanging component 1 and the hanging shaft tube 3.

(28) By using the glass base material hanging mechanism of the present embodiment, the hanging shaft tube and the hanging component can be connected to each other both tightly and vertically. As a result, the eccentricity during the deposition step of the optical fiber glass base material is decreased, the non-circularity, eccentricity, and bending during the sintering process are restricted, the non-circularity and bending during the elongating step are decreased, and the fiber curl, non-circularity, and eccentricity during the drawing step of the optical fiber are restricted.

LIST OF REFERENCE NUMERALS

(29) 1: hanging component, 2: wedge-shaped notch, 3: hanging shaft tube, 4: horizontal hole, 5: hanging pin, 6: center of mass, 7: contact point, 8: horizontal hole, 9: support point, 10: gap, 11: horizontal hole, 12: flat surface, 13: flat surface forming member, 14: vertical hole center, 15: outer diameter center, 16: flat surface