Preparation method of optical fiber preform

Abstract

The invention relates to the technical field of optical fiber preparation, and provides a preparation method of an optical fiber preform, which comprises the following steps: respectively fixing a head tube and a tail tube at two ends of a deposition lathe through a clamp; the deposition pipe is placed between the head pipe and the tail pipe, at least one end of the opposite ends of the head pipe and the deposition pipe and / or at least one end of the opposite ends of the deposition pipe and the tail pipe are heated, the to-be-flared heating ends of the head pipe, the deposition pipe and the tail pipe are subjected to flaring operation through a flaring component, and the flaring part of the flaring component is in a cone shape; welding the opposite ends of the head pipe and the deposition pipe and the opposite ends of the tail pipe and the deposition pipe; then core layers are formed on the head pipe, the deposition pipe and the tail pipe, and a core rod is formed after rod shrinkage; and sleeving the core rod to form the optical fiber preform. According to the invention, the formed flaring end is good in symmetry, so that the welding concentricity of the head pipe, the deposition pipe and the tail pipe is improved, the deposition of a core layer is uniform, and the quality of the optical fiber preform is improved.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber preparation, and in particular to a method for preparing an optical fiber preform. Background Art

[0002] Optical fiber, full name optical fiber, is a fiber made of glass or plastic. Optical fiber is mainly composed of core layer (fiber core), cladding and coating layer. The specific preparation process is to first deposit the core layer in the deposition tube by MCVD or PCVD method, and then melt the deposited deposition tube into a core rod. According to the requirements of the optical fiber core-to-cladding ratio, a sleeve of a certain thickness is placed on the core rod to further melt the core rod and the sleeve into a preform rod. The qualified preform rod is placed on the drawing tower for drawing. During the drawing process, the outer surface of the filament will be evenly coated with the inner coating and coating layer to form an optical fiber. The cladding of the double-clad optical fiber is divided into an inner cladding and an outer cladding. The deposition tube and the sleeve together constitute the inner cladding of the optical fiber, and the inner coating is the outer cladding of the optical fiber; the deposition tube and the sleeve of the single-clad optical fiber together constitute the cladding of the optical fiber.

[0003] In the process of depositing the core layer in the prior art, it is necessary to weld the head tube and the tail tube at both ends of the deposition tube, firstly, to facilitate the connection of the deposition tube with the fixtures at both ends of the deposition lathe, and secondly, to effectively utilize the preform rod and avoid waste. Since the diameters of the deposition tube, the head tube and the tail tube are usually different, before the two ends of the deposition tube are welded with the head tube and the tail tube, it is necessary to expand the deposition tube and / or one end or both ends of the head tube and / or the tail tube, so that the diameters of the ends of the deposition tube, the head tube and the tail tube to be welded after the expansion operation are the same, which is convenient for the concentric welding of the deposition tube, the head tube and the tail tube. Usually, the expansion operation is prone to asymmetric expansion due to errors, which makes it impossible for the head tube, the deposition tube and the tail tube to be welded concentrically, making the deposition tube easily in an inclined state, and the core layer deposition is uneven. In addition, during the deposition process, it is also necessary to detect the temperature of the outer wall of the deposition tube. If the deposition tube is set tilted, the accuracy of the temperature detection by the detection head will be reduced. During the deposition process, the deposition temperature cannot be accurately adjusted according to the needs, which affects the quality of the preform rod, so that the optical fiber cannot meet the customer's requirements, resulting in economic losses.

[0004] Therefore, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0005] The present invention provides a method for preparing an optical fiber preform, aiming to keep a deposition tube, a head tube and a tail tube concentric after fusion, so as to make the core layer deposited evenly, improve the accuracy of detecting the temperature of the outer wall of the deposition tube, and thus improve the quality of the preform.

[0006] The present invention provides a method for preparing an optical fiber preform rod, wherein the optical fiber comprises a deposition tube, a head tube and a tail tube, and the preparation method comprises the following steps: Step 1, fixing the head pipe and the tail pipe at two ends of a deposition lathe by means of a clamp respectively; Step 2, placing the deposition tube between the head tube and the tail tube, heating at least one of the opposite ends of the head tube and the deposition tube and / or at least one of the opposite ends of the deposition tube and the tail tube, and using an expanding component to expand the heated ends to be expanded among the head tube, the deposition tube and the tail tube, so that the ends of the head tube and the tail tube close to the deposition tube have the same diameter as the two ends of the deposition tube, respectively, wherein the expanding portion of the expanding component is in a cone shape; Step 3, welding the opposite ends of the head pipe and the deposition pipe, and welding the opposite ends of the tail pipe and the deposition pipe; Step 4, after the head tube, the deposition tube and the tail tube are fused, a core layer is formed on the head tube, the deposition tube and the tail tube, and the rod is shrunk to form a core rod; Step 5, performing a casing operation on the core rod to form an optical fiber preform.

[0007] According to the method for preparing an optical fiber preform provided by the present invention, the flaring component comprises a first conical cylinder and a second conical cylinder, and the diameters of the first conical cylinder and the second conical cylinder are different, and the bottoms of the first conical cylinder and the second conical cylinder are fixedly connected at a preset angle; In step 2, the step of using a flaring component to flare the heating ends to be flared in the head pipe, the deposition tube and the tail pipe includes: inserting the top end of the first conical column or the second conical column of the flaring component into the heating ends to be flared in the head pipe, the deposition tube and the tail pipe, so that the heating ends form corresponding flared ends.

[0008] According to the method for preparing an optical fiber preform provided by the present invention, in the step 2, before heating at least one of the opposite ends of the head tube and the deposition tube and / or at least one of the opposite ends of the deposition tube and the tail tube, the method further includes the following steps: A concentric component is placed at a position corresponding to the deposition tube, and the head tube, the deposition tube and the tail tube are arranged along the same axis through the concentric component.

[0009] According to the method for preparing an optical fiber preform provided by the present invention, in said step 2, after placing the concentric component at the position corresponding to said deposition tube and before the expansion operation, the method further comprises the following steps: The expansion component is fixed on the concentric component, and by adjusting the position of the concentric component, the first conical cylinder or the second conical cylinder is coaxially arranged with one of the head pipe, the deposition tube and the tail pipe to be expanded, and the head pipe, the deposition tube and the tail pipe are coaxially arranged at the same time.

[0010] According to the method for preparing an optical fiber preform provided by the present invention, the flaring component further comprises a handle, a first handle slot and a second handle slot are respectively provided at the center positions of the bottoms of the first conical cylinder and the second conical cylinder, a third handle slot is provided at the bottom of the connection between the first conical cylinder and the second conical cylinder, and the handle is connected to the first conical cylinder and / or the second conical cylinder through one of the first handle slot, the second handle slot and the third handle slot; In step 2, when the top end of the first conical cylinder is inserted into the heating ends to be expanded in the head pipe, the deposition tube and the tail pipe, the handle is fixed on the first conical cylinder through the first handle slot, and the handle is coaxially arranged with the first conical cylinder; when the top end of the second conical cylinder is inserted into the heating ends to be expanded in the head pipe, the deposition tube and the tail pipe, the handle is fixed on the second conical cylinder through the second handle slot, and the handle is coaxially arranged with the second conical cylinder; During non-expanding operation, if the head pipe, the tail pipe or the deposition tube needs support, the handle is fixed at the connection between the first conical cylinder and the second conical cylinder through the third handle slot, and the head pipe, the tail pipe or the deposition tube is supported by the angle between the first conical cylinder and the second conical cylinder.

[0011] According to the method for preparing an optical fiber preform provided by the present invention, the concentric component comprises a base, two supports and two half-buckle rings, the base is installed on the deposition lathe, the two supports are vertically arranged on the base and are respectively located on opposite sides of the base; the two half-buckle rings are respectively arranged on the top of the two supports, and the deposition tube is clamped on the concentric component by the two half-buckle rings; The two half-buckles are rotatably connected to the two supports respectively, the fixture is rotatably connected to the deposition lathe, the half-buckle is used to drive the deposition tube to rotate, the two fixtures are used to drive the head tube and the tail tube to rotate respectively, and the half-buckle and the fixture rotate in the same direction and at the same speed; In the step 2, when the expansion operation is performed, at least one of the head pipe, the deposition pipe and the tail pipe that needs to be expanded rotates at a constant speed on the deposition lathe; In the step 3, when the welding operation is performed, the head tube, the deposition tube and the tail tube are all rotated at a constant speed on the deposition lathe.

[0012] According to the method for preparing an optical fiber preform provided by the present invention, a plurality of scaled slide grooves are provided on the base, the plurality of slide grooves extend along the length direction and the width direction of the base respectively, the slide grooves extending along the length direction and the width direction of the base are arranged crosswise with each other, the two supports are both slidably installed in the slide grooves, and the heights of the two supports in the vertical direction are adjustable; Among them, the step of arranging the head pipe, the deposition tube and the tail pipe along the same axis through the concentric components includes: adjusting the positions of the two supports in the slide groove to adjust the position of the deposition tube relative to the head pipe and the tail pipe in the horizontal direction; and / or adjusting the heights of the two supports to adjust the position of the deposition tube relative to the head pipe and the tail pipe in the vertical direction, so that the head pipe, the deposition tube and the tail pipe are arranged along the same axis.

[0013] According to the method for preparing an optical fiber preform provided by the present invention, the diameters of the two half-buckle clamps can be adjusted, and each of the half-buckle clamps consists of two identical half rings, one end of the two half rings is movably connected, and the other end of the two half rings can be locked or opened by a buckle.

[0014] According to the method for preparing an optical fiber preform provided by the present invention, in step 1, the two clamps respectively clamp and fix the opposite ends of the head tube and the tail tube at the two ends of the deposition lathe, and the head tube and the tail tube are arranged along the same axis.

[0015] According to the method for preparing an optical fiber preform provided by the present invention, in step 3, the steps of fusing the opposite ends of the head tube and the deposition tube, and fusing the opposite ends of the tail tube and the deposition tube include: Heating at least one of the opposite ends of the head tube and the deposition tube to a molten state, and then contact-welding the opposite ends of the head tube and the deposition tube; At least one of the opposite ends of the tail pipe and the deposition tube is heated to a molten state, and then the opposite ends of the tail pipe and the deposition tube are contact-welded.

[0016] The above technical solution of the present invention has the following beneficial effects: The preparation method of the optical fiber preform provided by the present invention, by designing the flaring part of the flaring component into a cone shape, using the flaring component to flare the heating ends in the head tube, deposition tube and tail tube, can make the formed flared end symmetrical, so that the concentricity of the three-tube fusion of the head tube, deposition tube and tail tube can be improved, and this high degree of concentricity ensures that the core layer material can be evenly distributed on the tube walls of the deposition tube, head tube and tail tube during the deposition process, avoiding the quality fluctuation caused by uneven deposition, and significantly improving the uniformity and consistency of the core layer. Since the uniformity of the core layer deposition is significantly improved, the prepared optical fiber preform is also more uniform in structure, reducing internal defects and stress concentration points, thereby improving the overall quality of the optical fiber preform. In addition, since the concentricity of the three-tube fusion of the head tube, deposition tube and tail tube can be guaranteed, the accuracy of the temperature detection by the detection head can be further improved during the deposition process, thereby further improving the quality of the preform. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for preparing an optical fiber preform provided by an embodiment of the present invention; Figure 2 is a schematic diagram of an operating platform for an optical fiber preform provided by an embodiment of the present invention; Figure 3 A schematic cross-sectional view of a flaring component provided in an embodiment of the present invention; Figure 4 A front view of a first conical cylinder or a second conical cylinder of a flaring component provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of the base structure of the concentric components provided in an embodiment of the present invention.

[0019] Reference numerals: 1. head pipe; 2. flared end of head pipe; 3. tail pipe; 4. flared end of tail pipe; 5. deposition tube; 6. first clamp; 7. second clamp; 8. base; 9. first support; 10. second support; 11. first half-buckle; 12. second half-buckle; 13. first buckle; 14. second buckle; 15. first conical column; 16. second conical column; 17. handle; 18. first handle slot; 19. second handle slot; 20. third handle slot; 100. flaring component; 801. slide groove. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Combine the following Figure 1-Figure 5 The method for preparing the optical fiber core layer of the present invention is described in detail.

[0022] like Figure 1 and Figure 2 As shown, the optical fiber includes a deposition tube 5, a head tube 1 and a tail tube 3. The method for preparing the optical fiber core layer of the present invention includes the following steps: Step 1, fix the head pipe 1 and the tail pipe 3 on both ends of the deposition lathe by using a clamp; Step 2, placing the deposition tube 5 between the head tube 1 and the tail tube 3, heating at least one of the opposite ends of the head tube 1 and the deposition tube 5 and / or at least one of the opposite ends of the deposition tube 5 and the tail tube 3, and using the expanding component 100 to expand the heated ends to be expanded among the head tube 1, the deposition tube 5 and the tail tube 3, so that the ends of the head tube 1 and the tail tube 3 close to the deposition tube 5 have the same diameter as the two ends of the deposition tube 5, wherein the expanding portion of the expanding component 100 is conical; Step 3, welding the opposite ends of the head pipe 1 and the deposition pipe 5, and welding the opposite ends of the tail pipe 3 and the deposition pipe 5; Step 4, after the head tube 1, the deposition tube 5 and the tail tube 3 are fused, a core layer is formed on the head tube 1, the deposition tube 5 and the tail tube 3, and the rod is shrunk to form a core rod; Step 5, performing casing operation on the core rod to form an optical fiber preform rod.

[0023] It should be noted that the opposite ends of the head pipe 1 and the deposition tube 5 refer to one end of the head pipe 1 close to (or facing) the deposition tube 5 and one end of the deposition tube 5 close to (or facing) the head pipe 1; similarly, the opposite ends of the tail pipe 3 and the deposition tube 5 refer to one end of the tail pipe 3 close to (or facing) the deposition tube 5 and one end of the deposition tube 5 close to (or facing) the tail pipe 3.

[0024] Specifically, Figure 2 As shown, in this embodiment, the fixture includes a first fixture 6 and a second fixture 7, and the first fixture 6 and the second fixture 7 are respectively arranged at two ends of the deposition lathe. In step 1, the first fixture 6 and the second fixture 7 respectively clamp and fix the opposite ends of the head pipe 1 and the tail pipe 3 (i.e., the ends of the head pipe 1 and the tail pipe 3 that are away from each other), and the head pipe 1 and the tail pipe 3 are arranged along the same axis.

[0025] It is understandable that the diameters of the head tube, deposition tube and tail tube are not necessarily the same. The purpose of the expansion operation is to make the two tubes that are fused to each other maintain the same diameter at the fusion point, so as to better complete the fusion and improve the uniformity of the core layer deposition. The expansion operation can be to expand the smaller diameter of the two adjacent tubes, or to expand both adjacent tubes, which is not limited here.

[0026] Combination Figure 3 and Figure 4 As shown, the flaring component 100 includes a first conical cylinder 15, a second conical cylinder 16 and a handle 17. The diameters of the first conical cylinder 15 and the second conical cylinder 16 are different. The bottoms of the first conical cylinder 15 and the second conical cylinder 16 are fixedly connected at a preset angle. The first and second conical cylinders 15 and 16 are provided with a first handle slot 18 and a second handle slot 19 at the center of the bottom, respectively. The bottom of the connection between the first and second conical cylinders 15 and 16 is provided with a third handle slot 20. The handle 17 is connected to the first conical cylinder 15 and / or the second conical cylinder 16 through one of the first handle slot 18, the second handle slot 19 and the third handle slot 20. Of course, in other embodiments, the handle 17 can also be connected to the first conical cylinder 15 and / or the second conical cylinder 16 in other ways.

[0027] Combination Figure 2-Figure 4 As shown, in the above step 2, the step of using the expanding component 100 to expand the heating ends to be expanded in the head pipe 1, the deposition tube 5 and the tail pipe 3 includes: inserting the top end of the first conical column 15 or the second conical column 16 of the expanding component 100 into the heating ends to be expanded in the head pipe 1, the deposition tube 5 and the tail pipe 3, so that the heating ends to be expanded form corresponding expanded ends.

[0028] Specifically, when the top end of the first conical cylinder 15 is inserted into the heating end to be expanded in the head pipe 1, the deposition tube 5 and the tail pipe 3, the handle 17 is fixed on the first conical cylinder 15 through the first handle clamping groove 18, and the handle 17 is coaxially arranged with the first conical cylinder 15. When the top end of the second conical cylinder 16 is inserted into the heating end to be expanded in the head pipe 1, the deposition tube 5 and the tail pipe 3, the handle 17 is fixed on the second conical cylinder 16 through the second handle clamping groove 19, and the handle 17 is coaxially arranged with the second conical cylinder 16.

[0029] When at least one of the opposite ends of the head pipe 1 and the deposition tube 5 is expanded, at least one of the head pipe 1 and the deposition tube 5 that needs to be expanded rotates at a uniform speed on the deposition lathe, and the end of the head pipe 1 and the deposition tube 5 that needs to be expanded is heated by the lathe heating flame torch. When the end of the head pipe 1 and the deposition tube 5 that needs to be expanded is in a molten state, a expanding component is used to perform the expanding operation to form a uniformly symmetrical expanded end.

[0030] From the perspective of saving process and simplifying the manufacturing process, when the diameters of the head tube 1 and the deposition tube 5 are different, the one with the smaller diameter can be expanded. For example, when the diameter of the head tube 1 is smaller than the diameter of the deposition tube 5, before the head tube 1 and the deposition tube 5 are welded, the end of the head tube 1 close to the deposition tube 5 is expanded as needed to form the expanded end 2 of the head tube, so that the diameter of the expanded end 2 of the head tube is consistent with the diameter of the opposite side of the deposition tube 5, so that the head tube 1 and the deposition tube 5 can be better welded.

[0031] When expanding at least one of the opposite ends of the tail pipe 3 and the deposition tube 5, at least one of the tail pipe 3 and the deposition tube 5 that needs to be expanded rotates at a uniform speed on the deposition lathe, and the end of the tail pipe 3 and the deposition tube 5 that needs to be expanded is heated by the lathe heating flame torch. When the end of the tail pipe 3 and the deposition tube 5 that needs to be expanded is in a molten state, the expanding operation is performed to form a uniformly symmetrical expanded end.

[0032] From the perspective of saving process and simplifying the manufacturing process, when the diameters of the tail pipe 3 and the deposition tube 5 are different, the one with the smaller diameter can be expanded. For example, when the diameter of the tail pipe 3 is smaller than the diameter of the deposition tube 5, before the tail pipe 3 and the deposition tube 5 are welded, the end of the tail pipe 3 close to the deposition tube 5 is expanded as needed to form the tail pipe expanded end 4, so that the tail pipe 3 and the deposition tube 5 can be better welded.

[0033] During non-expanding operation, if the head pipe 1, the tail pipe 3 or the deposition tube 5 needs support, the handle 17 is fixed at the connection between the first conical column 15 and the second conical column 16 through the third handle slot 20, and the head pipe 1, the tail pipe 3 or the deposition tube 5 is supported by the angle between the first conical column 15 and the second conical column 16.

[0034] In this embodiment, the top end (tip) of the first conical cylinder or the second conical cylinder in the expanding component is inserted into the heating ends to be expanded in the head tube, the deposition tube and the tail tube. Since the first conical cylinder and the second conical cylinder are both cone-shaped, the expanded ends formed have good symmetry, thereby improving the concentricity of the fusion of the head tube, the deposition tube and the tail tube, making the core layer deposited evenly, thereby improving the quality of the optical fiber preform.

[0035] In one embodiment, before heating at least one of the opposite ends of the head pipe 1 and the deposition pipe 5 and / or at least one of the opposite ends of the deposition pipe 5 and the tail pipe 3 in the above step 2, the following steps are also included: A concentric component is placed at a position corresponding to the deposition tube 5, and the head pipe 1, the deposition tube 5 and the tail pipe 3 are arranged along the same axis through the concentric component.

[0036] like Figure 2As shown, the concentric component can be arranged below the deposition tube 5. The concentric component includes a base 8, two supports (i.e., a first support 9 and a second support 10) and two half-buckle rings (i.e., a first half-buckle ring 11 and a second half-buckle ring 12). The base 8 is mounted on a deposition lathe, and the first support 9 and the second support 10 are both vertically arranged on the base 8 and are respectively located on opposite sides of the base 8. The first half-buckle ring 11 and the second half-buckle ring 12 are respectively arranged on the top of the first support 9 and the second support 10, and the deposition tube 5 is clamped on the concentric component by the first half-buckle ring 11 and the second half-buckle ring 12.

[0037] Among them, the first half-buckle clamp 11 and the second half-buckle clamp 12 are rotatably connected to the first support 9 and the second support 10 respectively, the first clamp 6 and the second clamp 7 are rotatably connected to the deposition lathe respectively, the first half-buckle clamp 11 and the second half-buckle clamp 12 are both used to clamp the deposition tube 5 and jointly drive the deposition tube 5 to rotate, and the first clamp 6 and the second clamp 7 are respectively used to drive the head pipe 1 and the tail pipe 3 to rotate.

[0038] In the above step 2, when the expansion operation is performed, at least one of the head pipe 1, the deposition pipe 5 and the tail pipe 3 that needs to be expanded is rotated at a constant speed on the deposition lathe, and a well-symmetrical expanded end can be formed by using the expansion component.

[0039] Further, combined with Figure 2 and Figure 5 As shown, the base 8 is provided with a plurality of graduated slide grooves 801, which extend along the length direction and the width direction of the base 8 respectively, and the slide grooves 801 extending along the length direction and the width direction of the base 8 are arranged crosswise with each other, and the first support 9 and the second support 10 are both slidably installed in the slide grooves 801, and the first support 9 and the second support 10 can move forward, backward, left and right on the base 8 through the slide grooves 801. In addition, the height of the first support 9 and the second support 10 in the vertical direction is adjustable. Among them, the height adjustment method of the first support 9 and the second support 10 is not limited here.

[0040] Among them, the step of arranging the head pipe 1, the deposition tube 5 and the tail pipe 3 along the same axis through concentric components includes: adjusting the positions of the first support 9 and the second support 10 in the slide groove 801, thereby adjusting the position of the deposition tube 5 relative to the head pipe 1 and the tail pipe 3 in the horizontal direction; and / or adjusting the height of the first support 9 and the second support 10, thereby adjusting the position of the deposition tube 5 relative to the head pipe 1 and the tail pipe 3 in the vertical direction, so that the head pipe 1, the deposition tube 5 and the tail pipe 3 can be arranged along the same axis, thereby avoiding the problem of unequal welding of the deposition tube, the head pipe and the tail pipe due to errors such as manual visual operation.

[0041] In this embodiment, on the basis of the above embodiment, a concentric component is combined, which can avoid the problem of unequal welding of the deposition tube, the head tube and the tail tube due to manual operation, and can make the deposition tube, the head tube and the tail tube remain concentric after welding, so as to make the core layer deposition more uniform, improve the quality of the preform rod, reduce the defective rate of the optical fiber, and save costs.

[0042] Furthermore, in the above step 2, after placing the concentric component at the position corresponding to the deposition tube and before the expansion operation, the following steps are also included: The expansion component is fixed on the concentric component, and by adjusting the position of the concentric component, the first conical column or the second conical column is coaxially arranged with one of the head pipe, deposition tube and tail pipe to be expanded, and the head pipe, deposition tube and tail pipe are coaxially arranged at the same time.

[0043] By fixing the expanding component on the concentric component, when using the concentric component to adjust the concentricity of the head tube, deposition tube and tail tube, the first conical column or the second conical column can be adjusted to be coaxial with one of the head tube, deposition tube and tail tube to be expanded. In this way, the symmetry of the expanded ends formed by the head tube, tail tube and deposition tube can be further improved in the subsequent expanding operation, the concentricity of the three tubes after fusion is optimized, the core layer is deposited evenly, and the quality of the optical fiber preform is further improved.

[0044] Furthermore, a plurality of concentric components may be provided. When the deposition tube is expanded, one concentric component is used to fix the deposition tube, and another concentric component is used to fix the expanding component.

[0045] like Figure 2 As shown, in one embodiment, the diameters of the first half buckle type snap ring 11 and the second half buckle type snap ring 12 are adjustable. Specifically, each half buckle type snap ring is composed of two identical half rings, which are buckled relative to each other, wherein one end of the two half rings is movably connected, and the other end of the two half rings can be locked or opened by a buckle (the first buckle 13 or the second buckle 14).

[0046] In the above step 2, after placing the concentric components under the deposition tube 5, first adjust the inner diameters of the first half buckle snap ring 11 and the second half buckle snap ring 12 to make them the same as the diameter of the deposition tube 5; then open the first half buckle snap ring 11 and the second half buckle snap ring 12, place the deposition tube 5 in the first half buckle snap ring 11 and the second half buckle snap ring 12, close the first half buckle snap ring 11 and the second half buckle snap ring 12, and fix the first half buckle snap ring 11 through the first buckle 13 and the second buckle 14. and locked with the second half-buckle clamp 12; then, by adjusting the height and position of the first support 9 and the second support 10, the head pipe 1, the deposition tube 5 and the tail pipe 3 are placed concentrically; finally, the rotation direction and rotation speed of the first half-buckle clamp 11 and the second half-buckle clamp 12 are set through the control system, so that the first half-buckle clamp 11 and the second half-buckle clamp 12 drive the deposition tube 5 to rotate in the same direction and rotation speed as the first clamp 6 and the second clamp 7 during the welding operation.

[0047] Furthermore, the control system is connected to the driving components of the first half-buckle clasp 11 and the second half-buckle clasp 12 and the driving components of the first clamp 6 and the second clamp 7, so as to control the first half-buckle clasp 11 and the second half-buckle clasp 12 to rotate in the same direction and speed as the first clamp 6 and the second clamp 7 at both ends of the deposition lathe, thereby ensuring that the deposition tube 5, the head tube 1, and the tail tube 3 rotate in the same direction and speed, further improving the concentricity of the three-tube welding.

[0048] In one embodiment, the contact surfaces between the inner sides of the first half-buckle clasp 11 and the second half-buckle clasp 12 and the deposition tube 5 are both soft contact surfaces, so as to avoid damage to the deposition tube 5 when the first half-buckle clasp 11 and the second half-buckle clasp 12 contact the deposition tube 5.

[0049] Combination Figure 2 As shown, in the above step 3, the steps of welding the opposite ends of the head pipe 1 and the deposition pipe 5, and welding the opposite ends of the tail pipe 3 and the deposition pipe 5 include: At least one of the opposite ends of the head pipe 1 and the deposition tube 5 is heated to a molten state, and then the opposite ends of the head pipe 1 and the deposition tube 5 are contact-welded; and at least one of the opposite ends of the tail pipe 3 and the deposition tube 5 is heated to a molten state, and then the opposite ends of the tail pipe 3 and the deposition tube 5 are contact-welded.

[0050] For example, when the head pipe 1 is welded to the deposition tube 5, the head pipe flared end 2 is heated by a lathe heating flame torch, and when the head pipe flared end 2 is in a molten state, it is contact-welded with the deposition tube 5. Since the head pipe 1 is heated once at a high temperature when the head pipe flared end 2 is formed, the time of the welding operation can be shortened by continuing to heat the head pipe flared end 2 during welding. Similarly, when the tail pipe 3 is welded to the deposition tube 5, the tail pipe flared end 4 is heated by a lathe heating flame torch, and when the tail pipe flared end 4 is in a molten state, it is contact-welded with the deposition tube 5.

[0051] During the welding operation, the head pipe 1, the deposition pipe 5 and the tail pipe 3 are all rotated at a constant speed on the deposition lathe.

[0052] The preparation method of the optical fiber preform provided by the present invention designs the expanding part of the expanding component into a cone shape, and uses the expanding component to expand the heating ends of the head tube, the deposition tube and the tail tube, so that the formed expanded end has good symmetry, thereby improving the concentricity of the three-tube fusion of the head tube, the deposition tube and the tail tube, making the core layer deposition uniform, thereby improving the quality of the optical fiber preform. In addition, since the concentricity of the three-tube fusion of the head tube, the deposition tube and the tail tube can be guaranteed, the accuracy of the temperature detection of the detection head can be further improved during the deposition process, thereby further improving the quality of the preform.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an optical fiber preform, characterized in that: The optical fiber comprises a deposition tube, a head tube and a tail tube, and the preparation method comprises the following steps: Step 1, fixing the head pipe and the tail pipe at two ends of a deposition lathe by means of a clamp respectively; Step 2, placing the deposition tube between the head tube and the tail tube, heating at least one of the opposite ends of the head tube and the deposition tube and / or at least one of the opposite ends of the deposition tube and the tail tube, and using an expanding component to expand the heated ends to be expanded among the head tube, the deposition tube and the tail tube, so that the ends of the head tube and the tail tube close to the deposition tube have the same diameter as the two ends of the deposition tube, respectively, wherein the expanding portion of the expanding component is in a cone shape; Step 3, welding the opposite ends of the head pipe and the deposition pipe, and welding the opposite ends of the tail pipe and the deposition pipe; Step 4, after the head tube, the deposition tube and the tail tube are fused, a core layer is formed on the head tube, the deposition tube and the tail tube, and the rod is shrunk to form a core rod; Step 5, performing a casing operation on the core rod to form an optical fiber preform.

2. The method for preparing an optical fiber preform according to claim 1, characterized in that: The flaring component comprises a first conical cylinder and a second conical cylinder, and the diameters of the first conical cylinder and the second conical cylinder are different, and the bottoms of the first conical cylinder and the second conical cylinder are fixedly connected at a preset angle; In step 2, the step of using a flaring component to flare the heating ends to be flared in the head pipe, the deposition tube and the tail pipe includes: inserting the top end of the first conical column or the second conical column of the flaring component into the heating ends to be flared in the head pipe, the deposition tube and the tail pipe, so that the heating ends form corresponding flared ends.

3. The method for preparing an optical fiber preform according to claim 2, characterized in that: In step 2, before heating at least one of the opposite ends of the head pipe and the deposition pipe and / or at least one of the opposite ends of the deposition pipe and the tail pipe, the following steps are also included: A concentric component is placed at a position corresponding to the deposition tube, and the head tube, the deposition tube and the tail tube are arranged along the same axis through the concentric component.

4. The method for preparing an optical fiber preform according to claim 3, characterized in that: In step 2, after placing the concentric component at the position corresponding to the deposition tube and before the expansion operation, the following steps are also included: The expansion component is fixed on the concentric component, and by adjusting the position of the concentric component, the first conical cylinder or the second conical cylinder is coaxially arranged with one of the head pipe, the deposition tube and the tail pipe to be expanded, and the head pipe, the deposition tube and the tail pipe are coaxially arranged at the same time.

5. The method for preparing an optical fiber preform according to claim 2, characterized in that: The flaring component further includes a handle, a first handle slot and a second handle slot are respectively provided at the center positions of the bottoms of the first conical cylinder and the second conical cylinder, a third handle slot is provided at the bottom of the connection between the first conical cylinder and the second conical cylinder, and the handle is connected to the first conical cylinder and / or the second conical cylinder through one of the first handle slot, the second handle slot and the third handle slot; In step 2, when the top end of the first conical cylinder is inserted into the heating ends to be expanded in the head pipe, the deposition tube and the tail pipe, the handle is fixed on the first conical cylinder through the first handle slot, and the handle is coaxially arranged with the first conical cylinder; when the top end of the second conical cylinder is inserted into the heating ends to be expanded in the head pipe, the deposition tube and the tail pipe, the handle is fixed on the second conical cylinder through the second handle slot, and the handle is coaxially arranged with the second conical cylinder; During non-expanding operation, if the head pipe, the tail pipe or the deposition tube needs support, the handle is fixed at the connection between the first conical cylinder and the second conical cylinder through the third handle slot, and the head pipe, the tail pipe or the deposition tube is supported by the angle between the first conical cylinder and the second conical cylinder.

6. The method for preparing an optical fiber preform according to claim 3, characterized in that: The concentric component comprises a base, two supports and two half-buckle rings, the base is mounted on the deposition lathe, the two supports are vertically arranged on the base and are respectively located on opposite sides of the base; the two half-buckle rings are respectively arranged on the tops of the two supports, and the deposition tube is clamped on the concentric component by the two half-buckle rings; The two half-buckles are rotatably connected to the two supports respectively, the fixture is rotatably connected to the deposition lathe, the half-buckle is used to drive the deposition tube to rotate, the two fixtures are used to drive the head tube and the tail tube to rotate respectively, and the half-buckle and the fixture rotate in the same direction and at the same speed; In the step 2, when the expansion operation is performed, at least one of the head pipe, the deposition pipe and the tail pipe that needs to be expanded rotates at a constant speed on the deposition lathe; In the step 3, when the welding operation is performed, the head tube, the deposition tube and the tail tube are all rotated at a constant speed on the deposition lathe.

7. The method for preparing an optical fiber preform according to claim 6, characterized in that: The base is provided with a plurality of graduated slide grooves, the plurality of slide grooves respectively extending along the length direction and the width direction of the base, the slide grooves extending along the length direction and the width direction of the base are arranged crosswise with each other, the two supports are both slidably installed in the slide grooves, and the heights of the two supports in the vertical direction are adjustable; Among them, the step of arranging the head pipe, the deposition tube and the tail pipe along the same axis through the concentric components includes: adjusting the positions of the two supports in the slide groove to adjust the position of the deposition tube relative to the head pipe and the tail pipe in the horizontal direction; and / or adjusting the heights of the two supports to adjust the position of the deposition tube relative to the head pipe and the tail pipe in the vertical direction, so that the head pipe, the deposition tube and the tail pipe are arranged along the same axis.

8. The method for preparing an optical fiber preform according to claim 6, characterized in that: The diameters of the two half-buckles are adjustable. Each half-buckle consists of two identical half-rings, one end of the two half-rings are movably connected, and the other end of the two half-rings can be locked or opened by a buckle.

9. The method for preparing an optical fiber preform according to claim 1, characterized in that: In step 1, the two clamps respectively clamp and fix the opposite ends of the head pipe and the tail pipe at two ends of the deposition lathe, and the head pipe and the tail pipe are arranged along the same axis.

10. The method for preparing an optical fiber preform according to claim 1, characterized in that: In step 3, the steps of welding the opposite ends of the head pipe and the deposition pipe, and welding the opposite ends of the tail pipe and the deposition pipe include: Heating at least one of the opposite ends of the head tube and the deposition tube to a molten state, and then contact-welding the opposite ends of the head tube and the deposition tube; At least one of the opposite ends of the tail pipe and the deposition tube is heated to a molten state, and then the opposite ends of the tail pipe and the deposition tube are contact-welded.

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