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CN-224226902-U - Square optical fiber perform extrusion die

CN224226902UCN 224226902 UCN224226902 UCN 224226902UCN-224226902-U

Abstract

The utility model provides a square optical fiber preform extrusion die which comprises a sleeve, a piston, a nozzle, a fixing ring, a funnel-shaped through hole, a discharge hole, a round cross section, a concave circular arc-shaped cylinder and a glass fiber transmission beam, wherein the inside of the sleeve is sequentially divided into a filling cavity, a clamping groove and a fixing groove, the piston is arranged in the filling cavity, the nozzle is arranged in the clamping groove, the fixing ring is arranged in the fixing groove and is detachably connected with the fixing groove, the funnel-shaped through hole is formed in the nozzle, the upper end of the through hole is a feed port, the lower end of the through hole is a discharge port, the cross section of the feed port is circular, the four sides of the discharge port are approximate squares of concave circular arcs, when softened glass is discharged from the nozzle, the cross section of the discharge port is a cylinder with the four sides of which are approximate squares of concave circular arcs, and therefore when the glass is expanded outwards along the radial direction due to the surface tension, the concave circular arc is filled, and when the through hole is cooled and solidified, the optical fiber preform which is more approximate to the square is formed.

Inventors

  • QI SISHENG
  • REN HE
  • YANG ZHIYONG
  • QIU YU
  • JIANG YIGUANG
  • ZHANG LONG

Assignees

  • 中国科学院上海光学精密机械研究所

Dates

Publication Date
20260512
Application Date
20250509

Claims (6)

  1. 1. A square optical fiber preform extrusion die, comprising: The sleeve (1), the inside of the sleeve (1) is divided into a filler cavity (11), a clamping groove (12) and a fixing groove (13) from top to bottom in sequence; the piston (2) is arranged in the filler cavity (11) and slides up and down along the central shaft of the sleeve (1); A nozzle (3) provided inside the clamping groove (12); The fixing ring (4) is arranged in the fixing groove (13), and the side wall of the fixing ring is detachably connected with the fixing groove (13) through threads; wherein a funnel-shaped through hole is formed in the nozzle (3), the upper end of the through hole is provided with a feed inlet (31), and the lower end of the through hole is provided with a discharge outlet (32); The section of the feed port (31) is circular, and the diameter of the feed port is the same as the inner diameter of the filler cavity (11); The cross section of the discharge hole (32) is approximately square, four sides of the discharge hole are concave circular arcs, and the arc length and the curvature radius of the four concave circular arcs are the same.
  2. 2. The extrusion die for square optical fiber preform as claimed in claim 1, wherein, The inner diameters of the filler cavity (11), the clamping groove (12) and the fixing groove (13) are sequentially increased.
  3. 3. The extrusion die for square optical fiber preform as claimed in claim 1, wherein, The lower part of the nozzle (3) extends out of the clamping groove (12) to the inside of the fixing groove (13).
  4. 4. The extrusion die for square optical fiber preform as claimed in claim 1, wherein, The aperture of the fixed ring (4) is larger than the diagonal length of the discharge hole (32).
  5. 5. The extrusion die for square optical fiber preform as claimed in claim 1, wherein, The outer diameter length of the piston (2) is matched with the inner diameter length of the filler cavity (11), and the upper part of the piston (2) is provided with an internal threaded hole for being connected with the output end of the pushing device of the extruder.
  6. 6. The extrusion die for square optical fiber preform as claimed in claim 1, wherein, The sleeve (1), the piston (2), the nozzle (3) and the fixing ring (4) are all made of stainless steel.

Description

Square optical fiber perform extrusion die Technical Field The utility model relates to the technical field of preparation of optical fiber preforms, in particular to a square optical fiber preform extrusion die. Background The optical fiber image transmission beam is a passive image transmission device capable of being bent at will, and is formed by regularly arranging a plurality of tiny optical fiber monofilaments with certain length, wherein each optical fiber monofilament is used as independent transmission of one pixel without mutual interference, and enough pixels enable an image to be transmitted from one end of the optical fiber beam to the other end. The main properties of the fiber optic image-carrying beam include resolution and transmittance. And the transmittance is related to the monofilament loss and the packing fraction. The filling coefficient refers to the ratio of the occupied area of the fiber cores to the whole sectional area in the fiber bundle, and the transmittance of the fiber bundle can be effectively increased by increasing the ratio of the single fiber cores to the cladding (core-to-cladding ratio) and reducing the gaps between the fibers. However, at present, the conventional round optical fibers have unavoidable gaps when being arranged, so that even if the optical fiber bundle prepared by using the round optical fibers with large core-to-cladding ratio is used, the filling coefficient of the optical fiber bundle is reduced due to the influence of the gaps. The square section optical fiber is used to reduce the gap between the optical fibers, so that the influence of the optical fiber gap on the filling coefficient is eliminated, and the high-filling coefficient optical fiber image transmission beam is prepared. Generally, a square-section optical fiber preform with a large core-to-cladding ratio is prepared by a lamination extrusion process. At present, the publication number is CN108751694B, the name is the prior Chinese patent of a preparation method of an infrared chalcogenide glass optical fiber image transmission bundle with high filling coefficient, firstly, a lamination extrusion method is used for preparing a composite rod with a three-layer coaxial structure and a square cross section, the composite rod sequentially comprises fiber core chalcogenide glass, inner cladding chalcogenide glass and outer cladding thermoplastic polymer from inside to outside, then four composite rods with the same length are bundled and heat-treated into a 2X 2 array optical fiber preform rod, the 2X 2 array optical fiber is drawn into a 2X 2 array optical fiber, then the 2X 2 array optical fiber is piled up according to a square arrangement mode and heat-treated into an array optical fiber bundle rod, the array optical fiber multifilament is drawn into an array optical fiber multifilament bundle according to a square arrangement mode, and two ends of the array optical fiber multifilament bundle are heat-glued and wax-sealed, so that the infrared chalcogenide glass optical fiber image transmission bundle with high filling coefficient is obtained. However, in order to prevent breakage of the extruded glass during the production process, the extruded glass needs to be cooled to a temperature near the glass transition temperature for annealing treatment. Before reaching the annealing temperature, the glass is still in a softened state, and the square section of the optical fiber preform has a tendency to change towards a round shape due to factors such as surface tension and the like, so that the round arc shape of the four-sided microprotrusions is finally formed. This results in the optical fiber bundle prepared in this manner, while the arrangement is being prepared, there is still a fiber gap, affecting the improvement of the filling factor. Disclosure of utility model The utility model aims at solving the technical problems of the prior art, and provides a square optical fiber preform extrusion die, wherein a nozzle is clamped into the tail end of a sleeve, softened glass can enter from a feed inlet of the nozzle and is discharged from a discharge outlet when a piston extrudes a filler cavity in the sleeve, at the moment, the softened glass is extruded into a cylinder with a cross section of which four sides are concave circular arcs, the cross section of the cylinder is approximately square, the concave circular arcs are filled in the concave circular arcs when the glass expands outwards along the radial direction due to the surface tension, and the optical fiber preform is just formed to be more similar to the square optical fiber preform when the glass is cooled and solidified. In order to solve the technical problems, the utility model adopts the following technical scheme: a square optical fiber preform extrusion die, comprising: the inside of the sleeve is sequentially divided into a filler cavity, a clamping groove and a fixing groove from top to bottom; the piston is arranged in