A low-loss preform rod cone head processing method

Abstract

The present invention provides a low-loss preform cone head processing method, which relates to the field of optical fiber production technology. First, the optical fiber preform to be tapered is passed through a heating furnace in a horizontal state and clamped on a chuck; then, the blowtorch 1 is turned on and the timing is started, and the blowtorch 2 is turned on after 5 minutes to form a double-lamp temperature field to preheat the optical fiber preform; then, the taper is pulled, and the double-lamp temperature field is first used for heating during the taper pulling process, and the blowtorch 2 is turned off after 30 minutes, and the blowtorch 1 forms a single-lamp temperature field to heat the taper pulling position; after the taper is pulled to a double-cone head length of 30cm, the blowtorch 1 is turned off; then the heating furnace is moved to the middle of the taper pulling position, and the optical fiber preform is cooled and kept warm for 40 minutes; finally, the optical fiber preform is cut off from the middle position of the taper pulling to obtain two optical fiber preforms with cone heads. The present invention controls the shape of the produced cone head by controlling the temperature field range during the cone head processing process, so that the slope of the produced cone head becomes larger and the length becomes shorter, thereby reducing the loss generated during the processing of the cone head of a large-diameter optical fiber preform.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber production, and in particular to a method for processing a low-loss preform rod cone head. Background Art

[0002] The drawing production of optical fiber preform rods mainly uses a drawing furnace to heat the optical fiber preform rods, so that the optical fiber preform rods are stretched out from the lower end in a molten state. At the beginning of the drawing, in order to form a quartz lump at the lower end of the quartz rod, pull out qualified optical fiber with the core layer and cladding of the optical fiber preform rod, and make the ratio of the optical fiber core layer and cladding the same as that of the optical fiber preform rod, before the optical fiber preform rod is drawn, a streamlined cone head needs to be produced at the starting end of the optical fiber preform rod drawing.

[0003] With the continuous development of optical fiber drawing technology, in order to improve production efficiency and expand production capacity, the outer diameter of optical fiber preform is also developing towards larger diameter. The outer diameter of large-diameter optical fiber preform is generally 150mm. As the outer diameter of optical fiber preform increases, the loss of the starting part of the cone head on the optical fiber preform in the initial stage of drawing also increases. Among them, the shape of the cone head of the optical fiber preform has a direct impact on the loss caused by the cone head processing. If the cone head is too flat or too long, it will cause a large waste of glass. Summary of the invention

[0004] The object of the present invention is to provide a low-loss preform rod cone head processing method, by controlling the temperature field range during the cone head processing process to control the shape of the produced cone head, so that the slope of the produced cone head becomes larger and the length becomes shorter, thereby reducing the loss generated during the processing of the cone head of a large-diameter optical fiber preform rod.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A low-loss preform cone head processing method specifically comprises the following steps:

[0007] S1: loading; passing the optical fiber preform to be tapered through the heating furnace in a horizontal state, and clamping the two ends of the optical fiber preform on the chucks on the lathe respectively, wherein the chucks include a fixed left chuck and a movable right chuck; the position of the optical fiber preform to be tapered is located in the middle of the heating furnace, and the first and second blowtorches are arranged in parallel on one side of the position of the optical fiber preform to be tapered;

[0008] S2: preheating; turn on the first torch and start timing, turn on the second torch after 5 minutes, and the first and second torches form a double-lamp temperature field to preheat the optical fiber preform rod. The double-lamp preheating time is 20 minutes;

[0009] S3: taper; after preheating is completed, the right chuck is released, and the right chuck is driven to move the optical fiber preform 10mm to the right and then locked; after 3 minutes, the right chuck is released, and the right chuck is driven to move the optical fiber preform 20mm to the right and then locked, and the heating furnace is moved to the taper position of the optical fiber preform; after 2 minutes, the second blowtorch is turned off, and the first blowtorch forms a single-lamp temperature field to heat the taper position of the optical fiber preform; after 2 minutes, the right chuck is released, and the right chuck is driven to move the optical fiber preform 10mm to the right and then locked, and the heating furnace is moved to the middle position of the taper; thereafter, the right chuck is driven to move the optical fiber preform 10mm to the right every 1 minute, and the heating furnace is moved to the middle position of the taper; after repeating this 25 times, the first blowtorch is turned off, and the right chuck is driven to move the optical fiber preform 10mm to the right;

[0010] S4: Cooling; moving the heating furnace to the middle of the taper position, the optical fiber preform is cooled and kept warm for 40 minutes;

[0011] S5, cutting; after cooling, the heating furnace is removed to expose the taper position of the optical fiber preform, and the optical fiber preform is cut from the middle position of the taper to obtain two optical fiber preforms with taper heads.

[0012] Furthermore, in step S1, the straight-line distance between the lamp heads of the first and second blowtorches and the outer wall of the optical fiber preform is 6.5 cm-12.5 cm.

[0013] Furthermore, in step S2 and step S3, blowtorch 1 and blowtorch 2 are heated by burning propane plus oxygen; in step S2, the flow rates of blowtorch 1 and blowtorch 2 are both 75 L / min for propane and 320 L / min for oxygen; in step S3, when blowtorch 1 and blowtorch 2 are working at the same time, their flow rates are both 75 L / min for propane and 320 L / min for oxygen; when blowtorch 1 is working and blowtorch 2 is turned off, the flow rate of blowtorch 1 is 50 L / min for propane and 250 L / min for oxygen.

[0014] Further, in the step S3, the single-lamp temperature field is circular and covers the tapered position of the optical fiber preform, and the single-lamp temperature field includes a single-lamp high heat zone, a single-lamp medium heat zone, and a single-lamp low heat zone from the inside to the outside; in the steps S2 and S3, the double-lamp temperature field is elliptical and covers the tapered position of the optical fiber preform, and the double-lamp temperature field includes a double-lamp high heat zone, a double-lamp medium heat zone, and a double-lamp low heat zone from the inside to the outside.

[0015] Furthermore, the range of the high heat zone of the single lamp is a radius of 1 cm, the range of the medium heat zone of the single lamp is a radius of 1 cm-3 cm, and the range of the low heat zone of the single lamp is a radius of 3 cm-5 cm.

[0016] Furthermore, the range of the high heat zone of the double lamps is 3cm in the long axis and 1.5cm in the short axis, the range of the medium heat zone of the double lamps is 3cm-6cm in the long axis and 1.5cm-3cm in the short axis, and the range of the low heat zone of the double lamps is 6cm-8.5cm in the long axis and 3cm-5cm in the short axis.

[0017] Furthermore, in the steps S2 to S4, the optical fiber preform always rotates at a constant speed of 45 rpm.

[0018] Furthermore, in step S1, the outer diameter of the optical fiber preform to be tapered is 150 mm; in step S3, after the taper is completed, the cone head is a double-cone structure, the total length of the double-cone head is 30 cm, the diameter at the middle position of the double-cone head is the smallest, and the diameter at this position is 10 mm.

[0019] Furthermore, in step S4, after the heating furnace keeps the cone head of the optical fiber preform warm for 40 minutes, the outer surface temperature of the cone head of the optical fiber preform is 200° C.-300° C.

[0020] Furthermore, the specifications of the heating furnace are 60*60*60cm.

[0021] In summary, the present invention has the following beneficial effects:

[0022] In the preheating stage, the present invention first turns on the first blowtorch for preheating to avoid a sudden increase in the temperature of the optical fiber preform. Then, the second blowtorch is turned on to use double lamps for heating to form a double lamp temperature field for preheating. The first half of the taper is also heated by using the first and second blowtorches to form a double lamp temperature field. In the double lamp temperature field state, the double lamp high heat zone has a wide range, which is used to heat the entire area of ​​the optical fiber preform that needs to be reduced in diameter, and to perform preliminary taper reduction on the optical fiber preform. At this time, the cone head formed by the taper has a gentle slope. After half an hour, the second blowtorch is turned off, and only the first blowtorch is used to form a single lamp temperature field. The range of the single lamp high heat zone is narrowed, and the flame flow of the first blowtorch is reduced, so that the range of the single lamp high heat zone is further narrowed. Only the narrow middle area of ​​the optical fiber preform taper position is softened, and the rest of the parts are relatively firm. The cone head pulled out in the subsequent taper process will have a large slope.

[0023] The present invention switches the working states of blowtorch 1 and blowtorch 2 to form a double-lamp temperature field and a single-lamp temperature field, and adjusts the flame flow rate to control the temperature field range during the cone head processing process, thereby controlling the shape of the produced cone head, making the slope of the produced cone head larger and the length shorter, thereby reducing the loss generated during the processing of the cone head of a large-diameter optical fiber preform, and the flame flow rate adjustment can reduce the cost of gas use. The present invention sets special taper process parameters in conjunction with the temperature field range adjustment, so that the cone head shape produced is optimal and the loss generated is minimal, thereby improving the quality of the taper and reducing the cost of the taper. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of a method for processing a preform cone head with low loss;

[0025] Figure 2 It is a schematic diagram of the double-lamp temperature field in a low-loss preform cone processing method;

[0026] Figure 3 It is a schematic diagram of the temperature field of a single lamp in a low-loss preform cone processing method;

[0027] Figure 4 It is a schematic diagram of a cone head of an optical fiber preform rod with an outer diameter of 150 mm in the prior art;

[0028] Figure 5 The figure is a schematic diagram of an optical fiber preform cone head with an outer diameter of 150 mm produced by a low-loss preform cone head processing method.

[0029] In the figure, 1. Double-lamp temperature field; 11. Double-lamp high-heat zone; 12. Double-lamp medium-heat zone; 13. Double-lamp low-heat zone; 2. Single-lamp temperature field; 21. Single-lamp high-heat zone; 22. Single-lamp medium-heat zone; 23. Single-lamp low-heat zone. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] A low-loss preform cone head processing method, such as Figure 1 As shown, the specific steps include:

[0032] S1: Loading; The optical fiber preform to be tapered is passed through the heating furnace in a horizontal state, and the two ends of the optical fiber preform are respectively clamped on the chucks on the lathe. The chucks include a fixed left chuck and a movable right chuck. When taper is pulled, the right chuck drives one end of the optical fiber preform to move for taper. The position of the optical fiber preform to be tapered is located in the middle of the heating furnace. The inner wall of the heating furnace is provided with two blowtorches arranged side by side on one side of the optical fiber preform. The blowtorches include blowtorch 1 and blowtorch 2, and blowtorch 1 and blowtorch 2 correspond to the position of the optical fiber preform to be tapered. Among them, when installing the optical fiber preform to be tapered, it is necessary to ensure that the straight-line distance between the lamp heads of blowtorch 1 and blowtorch 2 and the outer wall of the optical fiber preform is 6.5cm-12.5cm, preferably 8.5cm. The outer diameter of the optical fiber preform to be tapered is a large diameter of 150mm, the specifications of the heating furnace are 60*60*60cm, and quartz bricks are laid inside the heating furnace for insulation.

[0033] S2: Preheating; turn on the blowtorch 1 and start timing, first use the blowtorch 1 to heat the optical fiber preform to avoid a sudden increase in the temperature of the optical fiber preform. Turn on the blowtorch 2 after 5 minutes, and the blowtorch 1 and the blowtorch 2 form a double-lamp temperature field 1 to preheat the optical fiber preform. The double-lamp preheating time is 20 minutes, and the total preheating time is 25 minutes. Among them, the blowtorch 1 and the blowtorch 2 are heated by the combustion method of propane plus oxygen, and during the preheating process, the flow rates of the blowtorch 1 and the blowtorch 2 are 75L / min for propane and 320L / min for oxygen for the first five minutes when the blowtorch 1 works alone and the last 20 minutes when the blowtorch 1 and the blowtorch 2 work simultaneously.

[0034] S3: Tapering; after preheating, start tapering, first loosen the right chuck, drive the right chuck to move the optical fiber preform 10mm to the right, and then lock the right chuck; loosen the right chuck after 3 minutes, drive the right chuck to move the optical fiber preform 20mm to the right, and then lock it, and move the heating furnace to the taper position of the optical fiber preform; turn off the second blowtorch after 2 minutes, and the first blowtorch forms a single lamp temperature field 2 to heat the taper position of the optical fiber preform. In other words, the timing starts from preheating, and the second blowtorch is turned off after 30 minutes, and the total working time of the second blowtorch is 25 minutes. After the blowtorch 1 works independently for 2 minutes, the right chuck is released, and the right chuck is driven to move the optical fiber preform rod to the right by 10mm, and then locked, and the heating furnace is moved to the middle position of the taper; thereafter, the right chuck is driven to move the optical fiber preform rod to the right by 10mm every 1 minute, and the heating furnace is moved to the middle position of the taper; after repeating this 25 times, the blowtorch 1 is turned off, and the right chuck is driven to move the optical fiber preform rod to the right by 10mm. At this time, the taper is completed, and a cone head with a double cone structure is formed in the middle position of the optical fiber preform rod, and the total length of the double cone head is 30cm. The diameter in the middle position of the double cone head is the smallest, and the diameter at this position is 10mm.

[0035] In step S3, when the initial blowtorch 1 and the blowtorch 2 work at the same time during the taper drawing, the flow rates of the blowtorch 1 and the blowtorch 2 are the same as those during preheating, and the flow rates are both 75L / min for propane and 320L / min for oxygen. When only the blowtorch 1 works and the blowtorch 2 is turned off during taper drawing, the flow rates of the blowtorch 1 are 50L / min for propane and 250L / min for oxygen. In this way, by switching the working states of the blowtorch 1 and the blowtorch 2 to form a double-lamp temperature field 1 and a single-lamp temperature field 2, and adjusting the flame flow rate, the temperature field range during the cone head processing process is controlled, thereby controlling the shape of the cone head produced, so that the slope of the cone head produced becomes larger and the length becomes shorter, thereby reducing the loss generated during the processing of the cone head of a large-diameter optical fiber preform, and the flame flow rate adjustment can reduce the cost of gas use.

[0036] In addition, if Figure 2As shown, in step S2 and step S3, the double-lamp temperature field 1 formed when the blowtorch 1 and the blowtorch 2 work simultaneously is elliptical and covers the taper position of the optical fiber preform, and the double-lamp temperature field 1 includes, from the inside to the outside, a double-lamp high-heat zone 11, a double-lamp medium-heat zone 12, and a double-lamp low-heat zone 13. Specifically, the double-lamp high-heat zone 11 has a range of 3 cm in the long axis and 1.5 cm in the short axis, the double-lamp medium-heat zone 12 has a range of 3 cm-6 cm in the long axis and 1.5 cm-3 cm in the short axis, and the double-lamp low-heat zone 13 has a range of 6 cm-8.5 cm in the long axis and 3 cm-5 cm in the short axis.

[0037] like Figure 3 As shown, in step S3, the single-lamp temperature field 2 formed by turning off the second blowtorch and working the first blowtorch is circular and covers the taper position of the optical fiber preform, and the single-lamp temperature field 2 includes, from the inside to the outside, a single-lamp high-heat zone 21, a single-lamp medium-heat zone 22, and a single-lamp low-heat zone 23. Specifically, the single-lamp high-heat zone 21 has a radius of 1 cm, the single-lamp medium-heat zone 22 has a radius of 1 cm-3 cm, and the single-lamp low-heat zone 23 has a radius of 3 cm-5 cm.

[0038] S4: Cooling: After the taper is completed, the heating furnace is moved to the middle of the taper position, and the heating furnace cools and keeps the optical fiber preform warm for 40 minutes until the outer surface temperature of the taper head of the optical fiber preform drops to 200℃-300℃. The heating furnace is used to keep the optical fiber preform warm after the taper is completed to prevent the optical fiber preform from being easily cracked due to rapid cooling from a high-temperature state, and to prevent the temperature from dropping too quickly, causing stress in the glass or directly cracking to release stress.

[0039] Among them, in step S2 to step S4, the optical fiber preform is always rotated at a constant speed of 45 rpm during the preheating, taper and cooling process to ensure that the taper position of the optical fiber preform is heated and cooled uniformly.

[0040] S5, cutting; after cooling, remove the heating furnace to expose the taper position of the optical fiber preform, and cut the optical fiber preform from the middle position of the taper, such as Figure 5 As shown, two independent optical fiber preforms with tapered heads are obtained.

[0041] Working principle and use method of the present invention:

[0042] When the present invention is used for taper drawing, blowtorch 1 and blowtorch 2 are first used to form a double-lamp temperature field 1 for heating. Under the state of the double-lamp temperature field 1, the double-lamp high-heat zone 11 is relatively wide, and is used to heat the entire area of ​​the optical fiber preform that needs to be reduced in diameter, and to perform preliminary taper drawing and diameter reduction on the optical fiber preform. At this time, the slope of the cone head formed by the taper drawing is relatively gentle. During the taper drawing process, blowtorch 2 is turned off, and only blowtorch 1 is used to form a single-lamp temperature field 2. The range of the single-lamp high-heat zone 21 becomes narrower, and at the same time, the flame flow of blowtorch 1 is reduced, so that the range of the single-lamp high-heat zone 21 is further narrowed. Only the narrow middle area of ​​the optical fiber preform taper position is softened, and the rest of the parts are relatively firm. The cone head pulled out in the subsequent taper drawing process will have a larger slope. Compared with the prior art Figure 4 Compared with the optical fiber preform cone head processed by the present invention, the optical fiber preform cone head processed by the present invention is as follows: Figure 5 As shown, the cone head is short and has a large slope, which can effectively reduce losses.

[0043] The present invention switches the working states of blowtorch 1 and blowtorch 2 to form a double-lamp temperature field 1 and a single-lamp temperature field 2, and adjusts the flame flow rate to control the temperature field range during the cone head processing, thereby controlling the shape of the produced cone head, making the slope of the produced cone head larger and the length shorter, thereby reducing the loss generated during the processing of the cone head of a large-diameter optical fiber preform, and the flame flow rate adjustment can reduce the cost of gas use. The present invention sets special taper process parameters in conjunction with the temperature field range adjustment, so that the cone head shape produced is optimal and the loss generated is minimal, thereby improving the quality of the taper and reducing the cost of the taper.

[0044] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A low-loss preform cone head processing method, characterized in that: The specific steps include: S1: loading; passing the optical fiber preform to be tapered through the heating furnace in a horizontal state, and clamping the two ends of the optical fiber preform on the chucks on the lathe respectively, wherein the chucks include a fixed left chuck and a movable right chuck; the position of the optical fiber preform to be tapered is located in the middle of the heating furnace, and the first and second blowtorches are arranged in parallel on one side of the position of the optical fiber preform to be tapered; S2: preheating; turn on the first torch and start timing, turn on the second torch after 5 minutes, and the first and second torches form a double-lamp temperature field (1) to preheat the optical fiber preform rod. The double-lamp preheating time is 20 minutes; S3: taper; after preheating is completed, release the right chuck, drive the right chuck to move the optical fiber preform 10mm to the right, and then lock the right chuck; after 3 minutes, release the right chuck, drive the right chuck to move the optical fiber preform 20mm to the right, and then lock it, and move the heating furnace to the taper position of the optical fiber preform; after 2 minutes, turn off the second blowtorch, and the first blowtorch forms a single-lamp temperature field (2) to heat the taper position of the optical fiber preform; after 2 minutes, release the right chuck, drive the right chuck to move the optical fiber preform 10mm to the right, and then lock it, and move the heating furnace to the middle position of the taper; thereafter, drive the right chuck to move the optical fiber preform 10mm to the right every 1 minute, and then move the heating furnace to the middle position of the taper; after repeating this 25 times, turn off the first blowtorch, drive the right chuck to move the optical fiber preform 10mm to the right; S4: Cooling; moving the heating furnace to the middle of the taper position, and cooling and keeping the optical fiber preform for 40 minutes; S5, cutting; after cooling, the heating furnace is removed to expose the taper position of the optical fiber preform, and the optical fiber preform is cut from the middle position of the taper to obtain two optical fiber preforms with taper heads; Among them, in step S2 and step S3, blowtorch 1 and blowtorch 2 are heated by burning propane plus oxygen; in step S2, the flow rates of blowtorch 1 and blowtorch 2 are both 75L / min for propane and 320L / min for oxygen; in step S3, when blowtorch 1 and blowtorch 2 are working at the same time, their flow rates are both 75L / min for propane and 320L / min for oxygen; when blowtorch 1 is working and blowtorch 2 is turned off, the flow rate of blowtorch 1 is 50L / min for propane and 250L / min for oxygen.

2. A low-loss preform cone head processing method according to claim 1, characterized in that: In the step S1, the straight-line distance between the lamp heads of the first and second blowtorches and the outer wall of the optical fiber preform is 6.5 cm to 12.5 cm.

3. A low-loss preform cone head processing method according to claim 1, characterized in that: In the step S3, the single-lamp temperature field (2) is circular and covers the taper position of the optical fiber preform, and the single-lamp temperature field (2) includes, from the inside to the outside, a single-lamp high-heat zone (21), a single-lamp medium-heat zone (22), and a single-lamp low-heat zone (23); in the steps S2 and S3, the double-lamp temperature field (1) is elliptical and covers the taper position of the optical fiber preform, and the double-lamp temperature field (1) includes, from the inside to the outside, a double-lamp high-heat zone (11), a double-lamp medium-heat zone (12), and a double-lamp low-heat zone (13).

4. A low-loss preform cone head processing method according to claim 3, characterized in that: The single-lamp high-heat zone (21) has a radius of 1 cm, the single-lamp medium-heat zone (22) has a radius of 1 cm-3 cm, and the single-lamp low-heat zone (23) has a radius of 3 cm-5 cm.

5. A low-loss preform cone head processing method according to claim 3 or 4, characterized in that: The range of the double-lamp high-heat zone (11) is 3 cm in long axis and 1.5 cm in short axis, the range of the double-lamp medium-heat zone (12) is 3 cm-6 cm in long axis and 1.5 cm-3 cm in short axis, and the range of the double-lamp low-heat zone (13) is 6 cm-8.5 cm in long axis and 3 cm-5 cm in short axis.

6. A low-loss preform cone head processing method according to claim 1, characterized in that: In the steps S2 to S4, the optical fiber preform always rotates at a constant speed of 45 rpm.

7. A low-loss preform cone head processing method according to claim 1, characterized in that: In the step S1, the outer diameter of the optical fiber preform to be tapered is 150 mm; in the step S3, after the taper is completed, the cone head is a double-cone structure, the total length of the double-cone head is 30 cm, the diameter at the middle position of the double-cone head is the smallest, and the diameter at the middle position is 10 mm.

8. A low-loss preform cone head processing method according to claim 1, characterized in that: In the step S4, after the heating furnace keeps the cone head of the optical fiber preform warm for 40 minutes, the outer surface temperature of the cone head of the optical fiber preform is 200° C.-300° C.

9. A method for processing a preform rod cone head with low loss according to claim 1, characterized in that: The specification of the heating furnace is 60cm*60cm*60cm.

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