Manufacturing method for glass substrate

Abstract

To provide a method for manufacturing a glass preform that can preferably form the glass preform even when lowering a flow rate of a raw material gas in a manufacturing process.SOLUTION: A method for manufacturing a glass preform includes: a first flow rate condition comprising a first raw material gas flow rate that is a flow rate of a raw material gas jetted from a raw material gas port and a first inert gas flow rate that is a flow rate of an inactive gas jetted from an inert gas port; and a second flow rate condition comprising a second raw material gas flow rate that is a flow rate of the raw material gas jetted from the raw material gas port and a second inert gas flow rate that is a flow rate of the inactive gas jetted from the inert gas port, where the first flow rate condition and the second flow rate condition can be switched; the first raw material gas flow rate is larger than the second raw material gas flow rate; and the first inert gas flow rate is smaller than the second inert gas flow rate.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a glass preform.

Background Art

[0002] A method for manufacturing a glass preform as described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes a method for manufacturing a glass preform in which an inert gas is ejected between a source gas, a combustion gas, and a combustion-supporting gas to form a glass preform. Further, the method for manufacturing a glass preform described in Patent Document 1 includes a deposition mode in which glass fine particles are deposited on a target member by a burner, and a non-deposition mode in which glass fine particles are not deposited on the target member, and it is described that the flow rate of the source gas is reduced in the non-deposition mode.

[0005] When the source gas is ejected into the flame formed by the combustion gas and the combustion-supporting gas, the source gas undergoes a flame hydrolysis reaction to generate glass fine particles, and the glass fine particles are deposited on the target member. By the way, in a state where the flow rate of the source gas is lowered, the flow velocity of the source gas ejected from the burner is reduced. In this state, when the reaction of the source gas occurs near the burner, glass fine particles are generated near the burner and adhere to the tip of the burner, and it may be impossible to form a glass preform in a desired shape.

[0006] This disclosure provides a method for manufacturing a glass matrix that can form a good glass matrix even if the flow rate of the raw material gas is reduced during the manufacturing process. [Means for solving the problem]

[0007] A method for manufacturing a glass base material according to one aspect of this disclosure is: A method for manufacturing a glass matrix, comprising generating glass microparticles by injecting a raw material gas into a flame formed by a burner, and depositing the glass microparticles onto a target member, The aforementioned burner, A raw material gas port from which the aforementioned raw material gas is ejected, An inert gas port is provided adjacent to and surrounding the aforementioned raw material gas port, and is used to eject an inert gas. A flame-forming port is provided around the aforementioned inert gas port and ejects combustion gas and combustion-supporting gas, Equipped with, The method for manufacturing the glass base material is as follows: A first flow rate condition consisting of a first raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a first inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port, The second flow rate condition includes a second raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a second inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port. It is possible to switch between the first flow rate condition and the second flow rate condition. The flow rate of the first raw material is greater than the flow rate of the second raw material, and the flow rate of the first inert gas is less than the flow rate of the second inert gas. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a method for manufacturing a glass matrix that can form a good glass matrix even if the flow rate of the raw material gas is reduced during the manufacturing process. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example of a glass substrate manufacturing apparatus capable of manufacturing a glass substrate using the glass substrate manufacturing method according to the embodiment of this disclosure. [Figure 2] This figure shows an example of a burner used for glass synthesis. [Figure 3] This figure shows an example of the flow rate conditions for each gas ejected from the burner. [Figure 4] This figure shows an example of the flow rate conditions for each gas at the start of glass nanoparticle deposition. [Figure 5] This is a schematic diagram showing a modified example of a glass substrate manufacturing apparatus. [Modes for carrying out the invention]

[0010] (Description of the embodiments of this disclosure) First, the embodiments of this disclosure will be listed and described. A method for manufacturing a glass base material according to one aspect of this disclosure is: (1) A method for manufacturing a glass matrix, comprising generating glass microparticles by injecting a raw material gas into a flame formed by a burner and depositing the glass microparticles onto a target member, The aforementioned burner, A raw material gas port from which the aforementioned raw material gas is ejected, An inert gas port is provided adjacent to and surrounding the aforementioned raw material gas port, and is used to eject an inert gas. A flame-forming port is provided around the aforementioned inert gas port and ejects combustion gas and combustion-supporting gas, Equipped with, The method for manufacturing the glass base material is as follows: A first flow rate condition consisting of a first raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a first inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port, The second flow rate condition includes a second raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a second inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port. It is possible to switch between a first flow rate condition and a second flow rate condition, the first raw material flow rate is larger than the second raw material flow rate, and the first inert gas flow rate is smaller than the second inert gas flow rate. According to the above manufacturing method, since the first raw material flow rate is larger than the second raw material flow rate and the first inert gas flow rate is smaller than the second inert gas flow rate, when switching from the first flow rate condition to the second flow rate condition, the flow rate of the raw material gas decreases, and the flow rate of the inert gas ejected between the raw material gas, the combustion gas, and the combustion-supporting gas increases. As a result, near the burner, it becomes difficult for the raw material gas, the combustion gas, and the combustion-supporting gas to react, so it becomes difficult for glass fine particles to adhere to the burner itself, and a glass base material can be formed well.

[0011] (2) The manufacturing method of (1) above is a method for manufacturing a glass base material in which the glass base material is formed in a long shape by reciprocally moving the burner relative to the target member, a glass base material is formed under the first flow rate condition with respect to the central portion of the target member, a glass base material may be formed under the second flow rate condition with respect to the end portion of the target member. In order to form the glass base material well, it is desirable to form the glass base material in a state where the flow rate of the raw material gas is reduced at the end portion of the target member compared to the central portion of the target member. By forming the glass base material under the first flow rate condition at the central portion of the target member and forming the glass base material under the second flow rate condition at the end portion of the target member as in the above manufacturing method, it becomes difficult for glass fine particles to accumulate on the burner itself.

[0012] (3) In the deposition start stage where no glass fine particles are deposited on the target member in the manufacturing method of (1) or (2) above, a glass base material may be formed under the second flow rate condition. In the deposition start stage where glass fine particles have not been deposited on the target member, in order to increase the bulk density of the glass fine particles and obtain the strength of the deposited glass base material, it is desirable to reduce the flow rate of the source gas. According to the above manufacturing method, in the deposition start stage, since the glass base material is formed under the second flow rate condition, even when the flow rate of the source gas is reduced in the deposition start stage, it is difficult for glass fine particles to adhere to the burner.

[0013] (4) In the second flow rate condition of the manufacturing method according to any one of (1) to (3) above, the ejection flow rate of the inert gas at the inert gas port may be greater than the ejection flow rate of the source gas at the source gas port. When the flow rate of the inert gas decreases near the burner tip, a reaction is likely to occur between the source gas, the combustion gas, and the combustion-supporting gas, and glass fine particles are likely to deposit on the burner tip and the glass fine particles already adhering to the burner tip. According to the above manufacturing method, in the second flow rate condition, the ejection flow rate of the inert gas at the inert gas port is greater than the ejection flow rate of the source gas at the source gas port, so it is difficult for a reaction to occur between the source gas, the combustion gas, and the combustion-supporting gas near the port.

[0014] (5) In the manufacturing method according to any one of (1) to (4) above, the flow rate regulator for adjusting the flow rate of the source gas supplied to the burner may be of the normally open type. A normally open type flow rate regulator is more difficult to control in a low flow rate range than a normally closed type flow rate regulator. For this reason, in the normally open type flow rate regulator, a hunting phenomenon in which the flow rate periodically rises and falls in a low flow rate range is likely to occur, and it may be difficult to maintain a constant flow rate. According to the above manufacturing method, even when the flow rate of the source gas is reduced by the normally open type flow rate regulator, it is difficult for glass fine particles to adhere to the burner, so a good manufacturing state of the glass base material can be maintained.

[0015] (Details of Embodiments of the Present Disclosure) Specific examples of methods for manufacturing glass substrates according to the embodiments of this disclosure will be described below with reference to the drawings. However, the present invention is not limited to these examples, and is intended to include all modifications within the meaning and scope of the claims, as defined by the claims.

[0016] Figure 1 is a schematic diagram showing an example of a glass base material manufacturing apparatus 1 capable of manufacturing a glass base material using the glass base material manufacturing method according to the embodiment of this disclosure. As shown in Figure 1, the glass base material manufacturing apparatus 1 comprises a reaction vessel 10 that houses a rotating target member 11, and a glass synthesis burner 20 that sprays glass fine particles toward the target member 11.

[0017] A through-hole (not shown) is provided in the upper wall of the reaction vessel 10, and a rod-shaped target member 11 is positioned so as to be inserted vertically through this through-hole. The upper end of the target member 11 is held by a holding part 12 of a rotary chuck 13. The rotary chuck 13 is movable vertically and is configured to rotate the holding part 12 around its axis. The rotary chuck 13 is configured to transmit a signal corresponding to its height position to the control unit (not shown) of the manufacturing apparatus. In addition, an exhaust pipe 14 is provided in the reaction vessel 10 on the side opposite to the burner 20, with the target member 11 in between. The exhaust pipe 14 exhausts a predetermined amount of gas and removes glass particles that float in the reaction vessel 10 without accumulating on the target member 11 to the outside.

[0018] Burner 20 generates glass nanoparticles by the hydrolysis reaction of a flame using various raw material gases such as SiCl4 and GeCl4 as a doping agent, for example, H2 gas as the combustion gas, O2 gas as the auxiliary combustion gas, and an inert gas such as N2 gas or Ar gas as the carrier gas or sealing gas. Here, the raw material gas refers to a gas containing various raw material gases. That is, it may be a mixed gas of various raw material gases such as SiCl4 and GeCl4 with other gases, or it may be the various raw material gases alone. The other gas may be, for example, a combustion gas or an auxiliary combustion gas, or it may be a gas containing an inert gas in addition to the combustion gas or auxiliary combustion gas. The burner 20 ejects the generated glass microparticles toward the target member 11, while the target member 11 rotates and moves back and forth in the vertical direction, thereby depositing the glass microparticles in a predetermined area of ​​the target member 11.

[0019] Figure 2 is a view of the burner 20 from the gas ejection side, that is, a view of the burner 20 from the glass base material 15 side in Figure 1. As shown in Figure 2, the burner 20 is composed of a raw material gas port 21 located in the center, an inert gas port 22 located adjacent to the raw material gas port 21 and surrounding the raw material gas port 21, and a flame forming port 25 located around the inert gas port 22. The flame forming port 25 is composed of a combustion gas port 23 located adjacent to the inert gas port 22 and surrounding the inert gas port 22, and a combustion aid gas port 24. The combustion aid gas port 24 is composed of an external combustion aid gas port 24b located adjacent to the combustion gas port 23 and surrounding the combustion gas port 23, and a plurality of internal combustion aid gas ports 24a (eight in this example) arranged within the combustion gas port 23 to surround the inert gas port 22. Note that inert gas may be supplied to the external combustion aid gas port 24b instead of combustion aid gas.

[0020] As shown in Figure 1, the burner 20 is connected to a gas supply device 26 via pipes 121, 122, 123, and 124 to supply each of the gas ports 21, 22, 23, and 24 described above. In addition, each of the pipes 121, 122, 123, and 124 is equipped with a flow regulator 27 (27a, 27b, 27c, 27d) to adjust the flow rate of each gas supplied from the gas supply device 26 to the burner 20.

[0021] Of the flow regulators 27, at least the raw material gas flow regulator 27a, which adjusts the flow rate of the gas supplied to the raw material gas port 21, is a normally open type regulator that is open when the power is off. The flow regulators 27 control the flow rate of each gas supplied to the burner 20 based on a control signal from the control unit (not shown) of this manufacturing apparatus.

[0022] Thus, the glass base material manufacturing apparatus 1 according to the embodiment of this disclosure is used in an OVD (external deposition) method in which glass fine particles are deposited on the target member 11 by relatively reciprocating a burner 20 and a target member 11 that rotates around an axis.

[0023] Next, a method for manufacturing the glass base material 15 using the glass base material manufacturing apparatus 1 will be described with reference to Figures 3 and 1. Figure 3 is a diagram showing the change in gas flow rate ejected from each gas port 21, 22, 23, and 24 of the burner 20 during the manufacturing of the glass base material 15.

[0024] As shown in Figure 3, a first flow rate condition and a second flow rate condition are set for the gas flow rates ejected from each gas port 21, 22, 23, and 24. The first flow rate condition is set so that the flow rate of the raw material gas ejected from the raw material gas port 21 becomes the first raw material gas flow rate A1, and the flow rate of the inert gas ejected from the inert gas port 22 becomes the first inert gas flow rate B1. The second flow rate condition is set so that the flow rate of the raw material gas ejected from the raw material gas port 21 becomes the second raw material gas flow rate A2, and the flow rate of the inert gas ejected from the inert gas port 22 becomes the second inert gas flow rate B2.

[0025] Under the first flow rate condition, the flow rate A1 of the first raw material gas injected is greater than the flow rate A2 of the second raw material gas injected under the second flow rate condition. Under the first flow rate condition, the flow rate B1 of the first inert gas injected is less than the flow rate B2 of the second inert gas injected under the second flow rate condition.

[0026] Furthermore, under the second flow rate condition, when comparing the ejection velocity of the inert gas ejected from the inert gas port 22 with the ejection velocity of the raw material gas ejected from the raw material gas port 21, the ejection velocity of the inert gas is greater than the ejection velocity of the raw material gas. The ejection velocity is the average flow velocity at the outlet of each gas port 21, 22, 23, and 24 of the burner 20, and is a value calculated from the flow rate / cross-sectional area of ​​each gas port 21, 22, 23, and 24.

[0027] Furthermore, under the second flow rate condition, when comparing the second inert gas flow rate B2 ejected from the inert gas port 22 with the second raw material gas flow rate A2 ejected from the raw material gas port 21, the second inert gas flow rate B2 is greater than the second raw material gas flow rate A2. Also, under the first flow rate condition, when comparing the first raw material gas flow rate A1 ejected from the raw material gas port 21 with the first inert gas flow rate B1 ejected from the inert gas port 22, the first raw material gas flow rate A1 is greater than the first inert gas flow rate B1.

[0028] Furthermore, comparing the second combustion gas flow rate C2, which is the flow rate of combustion gas ejected from the combustion gas port 23 under the second flow rate condition, with the first combustion gas flow rate C1, which is the flow rate of combustion gas ejected from the combustion gas port 23 under the first flow rate condition, the second combustion gas flow rate C2 is greater than the first combustion gas flow rate C1. Similarly, comparing the second auxiliary combustion gas flow rate D2, which is the flow rate of auxiliary combustion gas ejected from the auxiliary combustion gas port 24 under the second flow rate condition, with the first auxiliary combustion gas flow rate D1, which is the flow rate of combustion gas ejected from the auxiliary combustion gas port 24 under the first flow rate condition, the second auxiliary combustion gas flow rate D2 is greater than the first auxiliary combustion gas flow rate D1. Note that, of the two combustion gases, only the flow rate of the combustion gas may be increased under the second flow rate condition, while the flow rate of the auxiliary combustion gas may be kept constant under both the first and second flow rate conditions.

[0029] [Table 1]

[0030] As an example, as shown in Table 1, the raw material gas flow rate may be set to a ratio of 1:0.5 for the first flow rate condition and 1:0.5 for the second flow rate condition. The inert gas flow rate may be set to a ratio of 1:2 for the first flow rate condition and 1:1.2 for the second flow rate condition. The combustion gas flow rate may be set to a ratio of 1:1.2 for the first flow rate condition and 1:1.2 for the second flow rate condition. Furthermore, the total amounts of the raw material gas flow rate, inert gas flow rate, combustion gas flow rate, and auxiliary combustion gas flow rate under the first flow rate condition may be set to differ from the total amounts of the raw material gas flow rate, inert gas flow rate, combustion gas flow rate, and auxiliary combustion gas flow rate under the second flow rate condition.

[0031] The first flow rate condition is a flow rate condition in which glass microparticles are ejected to the center of the target member 11 in the longitudinal direction to form the effective portion of the glass base material 15. The effective portion is the part from which optical fibers, which will become the product, can be manufactured from the glass base material 15. The second flow rate condition is a flow rate condition in which glass microparticles are ejected to both ends of the target member 11 in the longitudinal direction to form the ineffective portion of the glass base material 15. For example, in the elongated glass base material 15 shown in Figure 1, the region from position Y1 to position Y2 in the longitudinal direction of the target member 11 is the center (effective portion), and the region from position Y2 to position Y3 and the region from position Y1 to position Y4 are the ends (ineffective portions).

[0032] Next, the change in gas flow rate shown in Figure 3 will be explained in relation to the production of the glass base material 15 by the glass base material manufacturing apparatus 1 shown in Figure 1. In Figure 3, the period from time t1 to time t2 is the period during which the burner 20 moves relatively upward in the region from position Y1 to position Y2 of the target member 11 while depositing glass microparticles, and the period from time t3 to time t4 is the period during which the burner 20 moves relatively downward in the region from position Y2 to position Y1 of the target member 11 while depositing glass microparticles.

[0033] During the manufacturing of the glass base material 15, the rotary chuck 13 sends a signal to the control unit corresponding to the height position of the rotary chuck 13. Based on the signal from the rotary chuck 13, the control unit calculates the height position (i.e., the deposition position) of the target member 11 facing the burner 20. The control unit may calculate the deposition position based not only on the signal from the rotary chuck 13 but also on signals used to control the rotary chuck 13.

[0034] As shown in Figure 1, during the manufacturing of the glass base material 15 by the glass base material manufacturing apparatus 1, the burner 20 is currently at the center of the longitudinal direction of the target member 11, and the burner 20 is moving upward relative to it (the target member 11 is moving downward relative to the burner 20).

[0035] In that state, based on the fact that the deposition position is between Y1 and Y2, the control unit controls the flow rate of each gas supplied from the flow regulators 27a, 27b, 27c, and 27d to the gas ports 21, 22, 23, and 24 respectively to match the gas flow rate of the first flow rate condition.

[0036] Next, after a predetermined time (time t2), when the deposition position reaches position Y2 in the upward movement, the control unit controls the flow rates of the gases supplied from flow regulators 27a, 27b, 27c, and 27d to gas ports 21, 22, 23, and 24 to match the gas flow rate of the second flow rate condition. As a result, gas under the first flow rate condition is ejected from gas ports 21, 22, 23, and 24 to the center of the target member 11 from position Y1 to position Y2 in the longitudinal direction, causing glass particles to be deposited, and at position Y2, the gas flow rate ejected from gas ports 21, 22, 23, and 24 is switched to the second flow rate condition.

[0037] Next, when the position of the burner 20 reaches position Y3, the rotary chuck 13 reverses the direction of movement of the target member 11, controlling the burner 20 to move downward relative to the target member 11 (the target member 11 moves upward relative to the burner 20).

[0038] Next, after a predetermined time (time t3), when the accumulation position by the burner 20 reaches position Y2 in the downward movement, the control unit controls the flow rate of each gas supplied from the flow regulators 27a, 27b, 27c, and 27d to the gas ports 21, 22, 23, and 24 to match the gas flow rate of the first flow rate condition. In this manner, near position Y3, which is the upper end of the target member 11 in the longitudinal direction, gas under the second flow rate condition is ejected from gas ports 21, 22, 23, and 24, causing glass particles to accumulate. Furthermore, at position Y2, the gas flow rate ejected from gas ports 21, 22, 23, and 24 is switched between the first and second flow rate conditions.

[0039] Next, after a predetermined time (time t4), when the deposition position by the burner 20 reaches position Y1 in the downward movement, the control unit controls the flow rate of each gas supplied from the flow regulators 27a, 27b, 27c, and 27d to the gas ports 21, 22, 23, and 24 to match the gas flow rate of the second flow rate condition. As a result, the gas under the first flow rate condition is ejected from the gas ports 21, 22, 23, and 24 to the center of the target member 11 from position Y2 to position Y1 in the longitudinal direction, depositing glass particles, and at position Y1, the gas flow rate ejected from the gas ports 21, 22, 23, and 24 is switched to the second flow rate condition.

[0040] Next, when the position of the burner 20 reaches position Y4, the rotary chuck 13 reverses the direction of movement of the target member 11, controlling the burner 20 to move relatively upward along the target member 11.

[0041] Next, after a predetermined time (time t5), when the accumulation position by the burner 20 reaches position Y1 in the upward movement, the control unit controls the flow rates of each gas supplied from the flow regulators 27a, 27b, 27c, and 27d to the gas ports 21, 22, 23, and 24 to match the gas flow rate of the first flow rate condition. In this manner, near the position of the lower end Y4 in the longitudinal direction of the target member 11, gas under the second flow rate condition is ejected from gas ports 21, 22, 23, and 24, causing glass particles to accumulate. Furthermore, at position Y1, the gas flow rate ejected from gas ports 21, 22, 23, and 24 is switched between the first and second flow rate conditions.

[0042] As these processing steps under the first and second flow rate conditions are repeated, a glass base material of the same diameter is formed in the central part under the first flow rate condition, while a glass base material with a smaller diameter towards the ends is formed at both the upper and lower ends under the second flow rate condition.

[0043] Next, the gas flow rate conditions at the deposition start stage in the manufacturing process of the glass base material 15, when the deposition of glass microparticles onto the target member 11 begins, will be explained with reference to Figure 4. Figure 4 shows the changes in the gas flow rate ejected from each gas port 21, 22, 23, and 24 of the burner 20 at the deposition start stage.

[0044] As shown in Figure 4, during the deposition initiation stage when the deposition of glass microparticles on the target member 11 begins, that is, during a predetermined period (time t01 to time t02) when no glass microparticles have been deposited on the target member 11, gas under the second flow rate condition is ejected from gas ports 21, 22, 23, and 24 to deposit glass microparticles on the target member 11. The predetermined period refers to, for example, the period until the surface of the target member 11 is uniformly deposited with glass microparticles with almost no gaps. In other words, during the deposition initiation stage, the glass base material 15 is formed under the second flow rate condition not only at the ends but also in the center of the target member 11, from the lower end Y4 to the upper end Y3 in the longitudinal direction of the target member 11. As described above, under the second flow rate condition, the second inert gas flow rate B2 of the inert gas is set to be greater than the second raw material gas flow rate A2 of the raw material gas.

[0045] Incidentally, when generating glass microparticles by injecting a raw material gas into a flame formed by combustion gas and a combustion-supporting gas, and depositing these glass microparticles onto a target material, reducing the flow rate of the raw material gas reduces the flow velocity of the raw material gas ejected from the burner. In this state, if the reaction of the raw material gas occurs near the burner, glass microparticles may be generated near the burner and adhere to the burner tip, making it difficult to form a glass base material properly. For example, when reducing the flow rate of the raw material gas, the flow rate may overshoot the target flow rate and gradually approach the target flow rate from a flow rate below the target flow rate. When the flow rate overshoots below the target flow rate, the raw material gas, combustion gas, and combustion-supporting gas are particularly likely to react near the burner, and the generated glass microparticles may adhere to the burner itself.

[0046] In contrast, according to the manufacturing method of the glass base material 15 of this embodiment, the first raw material gas flow rate A1 under the first flow rate condition is set to be greater than the second raw material gas flow rate A2 under the second flow rate condition, and the first inert gas flow rate B1 under the first flow rate condition is set to be less than the second inert gas flow rate B2 under the second flow rate condition. Therefore, when the flow rate of the gas ejected from the burner 20 switches from the first flow rate condition to the second flow rate condition, the flow rate of the raw material gas decreases from the first raw material gas flow rate A1 to the second raw material gas flow rate A2, and the flow rate of the inert gas ejected between the raw material gas and the combustion gas and auxiliary combustion gas increases from the first inert gas flow rate B1 to the second inert gas flow rate B2. As a result, the raw material gas and the combustion gas and auxiliary combustion gas do not react easily near the burner 20, so even if the flow rate of the raw material gas is reduced, glass particles do not easily adhere to the burner 20 itself, and the glass base material 15 can be formed well.

[0047] Furthermore, in the method for manufacturing the glass base material, in order to form the glass base material well, it is desirable to form the glass base material with a lower raw material gas flow rate at the ends of the target member than at the center of the target member. In contrast, in the method for manufacturing the glass base material 15 of this embodiment, the glass base material 15 is formed at the first raw material gas flow rate A1 of the first flow rate condition at the center of the target member 11 from position Y1 to position Y2, and the glass base material 15 is formed at the upper end from position Y2 to position Y3 and the lower end from position Y1 to position Y4 with a second raw material gas flow rate A2 of the second flow rate condition. This makes it possible to form the glass base material 15 well while making it difficult for glass particles to accumulate on the burner 20 itself.

[0048] In the manufacturing method of the glass base material 15 of this embodiment, at the deposition initiation stage when no glass microparticles have accumulated on the target member 11, gas under a second flow rate condition is ejected from the gas ports 21, 22, 23, and 24 of the burner 20 to deposit glass microparticles on the target member 11. At the deposition initiation stage when no glass microparticles have accumulated, it is desirable to increase the bulk density of the glass microparticles accumulated on the target member 11 to increase the strength of the glass microparticle deposit (glass base material 15). To increase the bulk density of the glass microparticles, it is desirable to reduce the flow rate of the raw material gas. With the above manufacturing method, at the deposition initiation stage, the glass base material 15 is formed under a second flow rate condition where the raw material gas is the second raw material gas flow rate A2, so the bulk density of the glass microparticles can be increased, and even when the flow rate of the raw material gas is reduced at the deposition initiation stage, glass microparticles are less likely to adhere to the burner 20.

[0049] In the manufacturing method of the glass base material 15 of this embodiment, under the second flow rate conditions, the ejection velocity of the inert gas at the inert gas port 22 is greater than the ejection velocity of the raw material gas at the raw material gas port 21. When the flow velocity of the inert gas decreases near the tip of the burner 20, a reaction is more likely to occur between the raw material gas and the combustion gas and auxiliary combustion gas, and glass particles are more likely to accumulate at the tip of the burner 20 and on glass particles already attached to the tip of the burner 20. According to the above manufacturing method, under the second flow rate conditions, since the ejection velocity of the inert gas at the inert gas port 22 is greater than the ejection velocity of the raw material gas at the raw material gas port 21, even if the flow rate of the raw material gas decreases, a reaction between the raw material gas and the combustion gas and auxiliary combustion gas near the port is less likely to occur, and glass particles are less likely to adhere to the burner 20.

[0050] In the manufacturing method of the glass base material 15 of this embodiment, the raw material gas flow regulator 27a (one of the flow regulators 27) that adjusts the flow rate of the raw material gas supplied to the burner 20 is a normally open type. Normally open type flow regulators are more difficult to control in the low flow rate range than normally closed type regulators. For this reason, normally open type flow regulators are prone to hunting phenomena in the low flow rate range, where the flow rate rises and falls periodically, making it difficult to maintain a constant flow rate. According to the above manufacturing method, even when the flow rate of raw material gas from the raw material gas port 21 is reduced by a normally open type flow regulator, the flow rate of inert gas from the inert gas port 22 is increased, making it difficult for glass particles to adhere to the burner 20, and thus maintaining a good manufacturing state of the glass base material 15.

[0051] In the manufacturing method of the glass base material 15 of this embodiment, under the second flow rate conditions, the second combustion gas flow rate C2 is greater than the first combustion gas flow rate C1, and the second auxiliary combustion gas flow rate D2 is greater than the first auxiliary combustion gas flow rate D1. In this way, by reducing the flow rate of the raw material gas and increasing the flow rates of the combustion gas and auxiliary combustion gas at the end of the target member 11, the bulk density of the deposited glass fine particles can be increased. This makes it possible to suppress crack formation (soot cracking) at the end of the glass base material 15.

[0052] (modified version) The above example describes the manufacturing of the glass base material 15 by the OVD method with a single burner, but is not limited to this. The glass base material manufacturing method according to the present invention may also use a glass base material manufacturing apparatus 100 equipped with a burner row consisting of a plurality of (e.g., 6) burners 120a, 120b, 120c, 120d, 120e, and 120f, as shown in Figure 5. The target member 11 rotates around its axis and reciprocates up and down relative to each burner 120a, 120b, 120c, 120d, 120e, and 120f as indicated by arrow Q. The range of reciprocation is smaller than that shown in the example in Figure 1. The manufacturing apparatus 100 can carry out a method for manufacturing a glass base material by depositing glass microparticles generated by each burner 120a, 120b, 120c, 120d, 120e, and 120f so as to cover a portion of the longitudinal direction of the target member 11, and by having adjacent burners deposit glass microparticles in a continuous area to form a single glass microparticle deposit. Although not shown in the figures, gas ports 21 to 24 are connected to each burner 120a, 120b, 120c, 120d, 120e, and 120f, respectively. In addition, in the manufacturing apparatus 100 shown in Figure 5, the same reference numerals are used for components that have the same function as those in the manufacturing apparatus 1 shown in Figure 1.

[0053] In the manufacturing apparatus 100 shown in Figure 5, the flow rates of the gases ejected from burners 120a and 120f, located at both ends of the vertical burner row, are switched between a first flow rate condition and a second flow rate condition. In contrast, the flow rates of the gases ejected from burners 120b, 120c, 120d, and 120e are maintained at the first flow rate condition. In the state shown in Figure 5, where the target member 11 has descended relative to the burner row, the flow rate of the gas ejected from burner 120a is switched to the first flow rate condition, and the flow rate of the gas ejected from burner 120f is switched to the second flow rate condition. As a result, the glass base material 15 can be formed at the center of the target member 11 under the first flow rate condition, and at the ends of the target member 11 under the second flow rate condition. In this modified example, as in the embodiments shown in Figures 1 to 4, glass particles are less likely to accumulate on the burner itself.

[0054] In this modified example, at the start of deposition, the glass base material 15 may be formed under the second flow rate conditions for all burners 120a, 120b, 120c, 120d, 120e, and 120f.

[0055] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Furthermore, the number, position, shape, etc. of the components described above are not limited to the above embodiments and can be changed to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0056] For example, in this embodiment, the target member is arranged in the vertical direction, but the manufacturing method described in this disclosure can also be applied when the target member is arranged in the horizontal direction. Furthermore, in this embodiment, glass microparticles may be deposited by the burner moving vertically instead of the target member. Even in this case, the manufacturing method of the present disclosure can be applied. [Explanation of Symbols]

[0057] 1,100 Glass base material manufacturing equipment 11 Target Member 12 Holding part 13 Rotary Chuck 14 Exhaust pipe 15 Glass base material 20,120a~120f Burner 21 Raw material gas port 22 Inert gas ports 23 Combustion gas ports 24. Combustion-supporting gas ports 24a Internal auxiliary combustion gas port 24b External auxiliary combustion gas port 25 Flame-forming ports 26 Gas supply equipment 27,27a,27b,27c,27d Flow regulator 27a Raw material gas flow regulator 27b Inert gas flow regulator 27c Combustion gas flow regulator 27d Combustion auxiliary gas flow rate regulator 121, 122, 123, 124 Piping A1 Primary raw material gas flow rate A2 Second raw material gas flow rate B1 First inert gas flow rate B2 Second inert gas flow rate C1 First combustion gas flow rate C2 Second combustion gas flow rate D1 First auxiliary combustion gas flow rate D2 Second auxiliary gas flow rate

Claims

1. A method for manufacturing a glass matrix, comprising generating glass microparticles by injecting a raw material gas into a flame formed by a burner, and depositing the glass microparticles onto a target member, The aforementioned burner, A raw material gas port from which the aforementioned raw material gas is ejected, An inert gas port is provided adjacent to and surrounding the aforementioned raw material gas port, and is used to eject an inert gas. A flame-forming port is provided around the aforementioned inert gas port and ejects combustion gas and combustion-supporting gas, Equipped with, The method for manufacturing the glass base material is as follows: A first flow rate condition consisting of a first raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a first inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port, The second flow rate condition includes a second raw material flow rate, which is the flow rate of the raw material gas ejected from the raw material gas port, and a second inert gas flow rate, which is the flow rate of the inert gas ejected from the inert gas port. It is possible to switch between the first flow rate condition and the second flow rate condition. The flow rate of the first raw material is greater than the flow rate of the second raw material, and the flow rate of the first inert gas is less than the flow rate of the second inert gas. A method for manufacturing glass substrates.

2. A method for manufacturing a glass base material, wherein the burner is moved back and forth relative to the target member to form a long glass base material, A glass base material is formed in the central part of the target member under the first flow rate conditions. For the end of the target member, a glass base material is formed under the second flow rate conditions. A method for manufacturing a glass base material according to claim 1.

3. A method for manufacturing a glass matrix according to claim 1, wherein a glass matrix is ​​formed under the second flow rate conditions at the deposition initiation stage when glass fine particles have not yet accumulated on the target member.

4. The method for manufacturing a glass base material according to claim 1, wherein, under the second flow rate conditions, the ejection velocity of the inert gas in the inert gas port is greater than the ejection velocity of the raw material gas in the raw material gas port.

5. The method for manufacturing a glass base material according to any one of claims 1 to 4, wherein the flow regulator for adjusting the flow rate of the raw material gas supplied to the burner is of the normally open type.

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