A device for expanding and stretching circular diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery.

Abstract

This invention discloses an expansion and stretching device for circular diameter expanded polytetrafluoroethylene (ePTFE) monofilament sutures used in medical surgery. The device includes an expansion heating device and a stretching heating device arranged sequentially, with a front air-cooling zone and a rear air-cooling zone between them. The expansion heating device includes a first heating cavity with first guide wheels on both sides and a first heating plate with guide grooves inside. The stretching heating device includes a second heating cavity with a second heating plate inside. This invention can manufacture medical ePTFE sutures with a diameter of 0.05-0.30 mm. The material has good chemical stability, is non-rejecting, does not breed bacteria, and is compatible with human tissues. Furthermore, it prevents suture splitting during use, reducing postoperative residue due to suture twisting, thus improving patient comfort and reducing the risk of bacterial infection.

Description

Technical Field

[0001] This invention relates to the field of medical suture device technology, specifically to an expansion and stretching device for a circular diameter expanded polytetrafluoroethylene monofilament suture for medical surgery. Background Technology

[0002] Currently, polytetrafluoroethylene (PTFE), a high-molecular polymer, is widely used in the medical field, such as in expanded PTFE (ePTFE) artificial blood vessels, artificial skin, heart valves, fillers for breast and nose augmentation, and non-absorbable surgical sutures. PTFE products can be used for extended periods within a very wide temperature range (-196~260℃) and exhibit excellent chemical corrosion resistance, remaining unaffected by concentrated sulfuric acid, concentrated hydrochloric acid, and caustic soda. In terms of physical properties, it has a very low coefficient of friction (the coefficient of friction for fiber materials is <0.1) and is unaffected by ultraviolet radiation. Long-term testing has also revealed that expanded PTFE materials (pudding) possess biocompatibility. The expansion of PTFE refers to the fact that due to the long and unbranched molecular chains of PTFE, under certain temperature conditions, the molecular chains in its high-elasticity region are stretched and oriented, forming gaps (micropores in the industry) between the molecular chains. This gives PTFE materials elasticity and softness. Furthermore, microporous structures can appear after high-multidirectional stretching.

[0003] In 1969, the American company Gore invented ePTFE and certified that, in addition to the inherent stability, chemical resistance, heat resistance, UV resistance, and good abrasion resistance and low friction properties of PTFE, expanded polytetrafluoroethylene (ePTFE) has broadened its application range due to improved creep resistance and abrasion resistance. It can be used as a high-performance medical polymer material in human medical applications and the manufacture of medical devices. Due to its extremely stable chemical resistance (non-decomposition), without carcinogenic or sensitizing side effects, human tissue cells and blood vessels can grow into its expanded micropores, forming tissue connections, just like autologous tissue. This tissue healing method is superior to the traditional method of tissue healing encapsulated with silicone rubber fibers. Currently, expanded polytetrafluoroethylene is widely used in artificial blood vessels, sutures, and facial implants. Multiple studies show that ePTFE is a biocompatible and chemically stable medical biomaterial.

[0004] Polytetrafluoroethylene (PTFE) is one of the few substances that does not exhibit liquid flowability in its molten state. Therefore, fibers made from this material cannot be produced using melt spinning technology to create products such as monofilaments. Currently, these monofilaments are primarily produced using two methods: "paste plunger extrusion" and "paste roll-to-film slitting." The former produces round monofilaments, while the latter produces flat filaments. Currently, imported products used clinically include non-absorbable sutures produced by foreign companies such as Gore & Braun (USA) and others (brand names GORE-BRAUN). The product (registration number 20172021669) is made of expanded polytetrafluoroethylene (ePTFE). However, in clinical use, doctors have reported that this suture tends to fork during use. Close inspection reveals that the suture's cross-section resembles that of a rolled-up membrane. Further analysis confirms that sutures produced by companies like Gore are manufactured using a splitting process. This forking causes difficulties for surgeons, creating resistance and causing discomfort to patients. Furthermore, the twisting during suturing can lead to the formation of interlayers, easily trapping blood, bodily fluids, and other substances, ultimately becoming dirt and causing bacterial infection of the wound.

[0005] The applicant possesses a mature technology for producing PTFE monofilament using plunger extrusion, holding invention patents "A Method for Producing Continuous Filaments" (ZL 201610621069.5), "A Stroke-Segmented Hydraulic Plunger Extrusion Method" (ZL202111054621.4), and utility model patent "A Heating and Degreasing Device for Polytetrafluoroethylene Monofilament" (ZL 202222117953.9), among other original production technologies using plunger extrusion to produce PTFE monofilament. The oil-containing PTFE raw filament extruded using this technology is inherently round and has a very smooth surface. After undergoing special temperature-controlled degreasing, expansion, and stretching processes different from non-expanded PTFE sewing thread, a round-diameter expanded ePTFE monofilament can be obtained. By using different stretching speed ratios, monofilaments of different diameters can be produced. After medical treatment, it can be used as a non-absorbable expanded polytetrafluoroethylene (ePTFE) surgical suture for medical use.

[0006] The device for which this invention patent is applied is a device specifically designed to achieve the purpose of round diameter, expansion and softness based on various PTFE monofilament manufacturing processes. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an expansion and stretching device for circular diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery, which can manufacture medical expanded polytetrafluoroethylene sewing thread with a thread diameter of 0.05-0.30mm. The material has good chemical stability, is non-rejecting, does not breed bacteria, and has good compatibility with human tissues. At the same time, the sutures do not split during use, reducing the possibility of residual dirt due to thread twisting after surgery. This reduces the chance of bacterial infection while making the patient more comfortable.

[0008] To address the aforementioned technical problems, this invention provides an expansion and stretching device for circular diameter expanded polytetrafluoroethylene (ePTFE) monofilament sewing thread used in medical surgery. The device comprises an expansion heating device and a stretching heating device arranged sequentially, with a front air-cooling zone and a rear air-cooling zone between them. The expansion heating device includes a first heating cavity, with first guide wheels on both sides of the first heating cavity, and a first heating plate inside the first heating cavity, with guide grooves on the first heating plate. The stretching heating device includes a second heating cavity, with a second heating plate inside the second heating cavity.

[0009] Furthermore, both the first heating cavity and the second heating cavity are equipped with a sliding cover mechanism.

[0010] Furthermore, the guide wire groove is provided with three identical grooves, namely the first groove, the second groove and the third groove. The arc angle of the first guide wire wheel is not greater than 180°. The parameters of the first heating cavity are as follows: thickness 3-5mm, built-in heat insulation cotton, inner cavity space width 10-30cm, height 8-12cm, length 80-120cm, the first heating plate is placed in the cavity from the bottom, and the length and width of the inner cavity space are adapted to the size of the above-mentioned space, and the height is 5-8cm.

[0011] With the middle part of the inner cavity as the reference and the intersection of the left and right three equal parts as the center point, a 1-2cm hole is opened through the first heating cavity and an electric heating rod is inserted as a heat source.

[0012] The first, second, and third grooves are 1-1.5cm wide and 0.8-1.2cm deep; and the two ends of the cavity are sealed and equipped with three corresponding U-shaped openings.

[0013] Furthermore, metal plates extending 5-10cm from the bottom surfaces of both ends of the first heating cavity are installed on the right end of the first groove and the middle part of the second groove, and the diameter of the first guide wheel is equal to the distance between the center lines of the first groove and the second groove.

[0014] A first guide wheel of the same size is also provided between the second and third slots. The first guide wheel is driven by a coaxial motor with adjustable speed.

[0015] Furthermore, the second heating plate is an arc-shaped chrome-plated heating plate, the edge of the second heating plate is flush with the openings on both sides of the second heating cavity, and the heating wires on the second heating plate are attached to the heating plate and travel an S-shaped path.

[0016] The second heating plate is 10-30cm wide, 5-8cm thick, and 80-120cm long. In the length direction, the surface of the second heating plate is a parabolic arc with an angle of 5°-8°. It is chrome-plated and polished.

[0017] Furthermore, it includes a stretching device system, which comprises a gripping roller group and a dragging roller group.

[0018] Furthermore, the gripping roller assembly includes a power-driven main roller, and a combination of a pressure roller and a splitting roller that form a pair with the main roller;

[0019] The main roller and the driven pressure roller are made of fluorosilicone rubber surface layer;

[0020] The splitting roller has 8-10 wire grooves machined on its surface. The wire grooves are semi-circular and have a depth between 0.2-0.5 mm.

[0021] The beneficial effects of this invention are:

[0022] 1. Both heating chambers are heated internally with heat preservation, the temperature is controllable, the line is heated evenly, heat loss is reduced, and energy loss is reduced; the sliding cover opens automatically to prevent employees from being burned and to protect their safety.

[0023] 2. The first heating plate adopts a groove-shaped expanded heating plate, which is conducive to wire guiding, can avoid wire tangling, and improve winding efficiency.

[0024] 3. The two guide wheels are folded at an arc (α) ≤ 180° with the contact surface of the yarn to avoid excessive stretching of the yarn in an incompletely expanded state under large arc conditions, which would cause the yarn to deform. The guide wheels are driven by a micro motor, which can also reduce the friction caused by the passive rotation and folding of the yarn, thus preventing it from deforming under force.

[0025] 4. The pre-cooling zone and post-cooling zone before entering the gripping roller and drawing roller can effectively cool the heated yarn, allowing the molecular structure to solidify and form quickly, preventing irreversible deformation caused by the clamping and squeezing of the gripping roller.

[0026] 5. The gripping roller group at the front end of the drafting device system consists of a main roller, a pressure roller, and a splitting roller. Its features include: ① To increase and stabilize the gripping force and overcome the weakness of slippage due to the low coefficient of friction of PTFE, the main roller and pressure roller are designed with a fluorosilicone rubber coating. This solves the problem of stable gripping force and also reduces the squeezing pressure on the yarn due to the moderate softness of the fluorosilicone rubber, thereby reducing yarn deformation. Simultaneously, a splitting roller is used on the side of the main roller. The yarn, constrained by the grooves of the splitting roller, can be evenly distributed on the main roller surface, preventing entanglement and compression deformation.

[0027] 6. The second heating plate of the stretching heating device is designed with a slightly convex arc shape, and the second guide wheels at both ends are slightly lower than the plate surface, so as to give the wire a certain tension and make it heat evenly during the stretching process; while the smooth chrome-plated surface of the second heating plate can protect the wire from scratches or fuzzing due to friction.

[0028] 7. The design of the combination of the main roller and the splitting roller, as well as the drawing roller and the splitting roller, utilizes an irregular ellipse formed by two unequal circles to increase and stabilize the cohesion between the yarn and the roller; while the grooves that can be embedded in the yarn are engraved on the auxiliary roller, which not only increases the friction of the yarn roller, but also protects the roundness of the yarn diameter, and at the same time plays a role in splitting the yarn, preventing the yarn from getting tangled and squeezed on the drawing roller. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the puffing heating device of the present invention.

[0030] Figure 2 This is a schematic diagram of the first heating cavity structure of the present invention.

[0031] Figure 3 This is a schematic cross-sectional view of the first heating cavity of the present invention.

[0032] Figure 4 This is a schematic diagram of the tensile heating device of the present invention.

[0033] Figure 5 This is a schematic diagram of the second heating plate structure of the present invention.

[0034] Figure 6 This is a schematic diagram of the operating structure of the gripping roller assembly of the present invention.

[0035] Figure 7 This is a schematic diagram of the structure of the rear air-cooled unit, the drawing roller group, and the take-up cylinder of the present invention.

[0036] Figure 8 This is a schematic diagram of the rear air-cooling zone and the traction roller assembly of the present invention.

[0037] The following are the labels in the diagram: 1. Expansion heating device; 2. Stretching heating device; 3. First heating chamber; 4. First guide roller; 5. First heating plate; 6. First groove; 7. Second groove; 8. Third groove; 9. Second heating chamber; 10. Second guide roller; 11. Second heating plate; 12. Sliding cover mechanism; 13. Main roller; 14. Pressure roller; 15. Dividing roller; 16. Coaxial motor. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0043] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0044] Reference Figures 1 to 8 As shown, an embodiment of the expansion and stretching device for circular diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery according to the present invention includes an expansion heating device 1 and a stretching heating device 2 arranged sequentially, with a front air-cooling zone and a rear air-cooling zone between the expansion heating device 1 and the stretching heating device 2; the expansion heating device 1 includes a first heating cavity 3, with first guide wheels 4 arranged on both sides of the first heating cavity 3, and a first heating plate 5 arranged inside the first heating cavity 3, with guide grooves arranged on the first heating plate 5; the stretching heating device 2 includes a second heating cavity 9, with second guide wheels 10 arranged on both sides of the second heating cavity 9, and a second heating plate 11 arranged inside the second heating cavity 9.

[0045] Both the first heating cavity 3 and the second heating cavity 9 are equipped with a sliding cover mechanism 12; the guide wire groove has three identical structures, namely the first groove 6, the second groove 7, and the third groove 8; the arc angle of the first guide wire wheel 4 is not greater than 180°; the parameters of the first heating cavity 3 are as follows: thickness 3-5mm, built-in insulation cotton, inner cavity space width 10-30cm, height 8-12cm, length 80-120cm, the first heating plate is placed in the cavity from the bottom, and the length and width of the inner cavity space are adapted to the above-mentioned size, with a height of 5-8cm; the inner cavity... The center point is the intersection of the middle part (based on height) and the three equal parts on the left and right sides. A 1-2cm hole is opened through the first heating cavity 3 to insert an electric heating rod as a heat source. The dimensions of the first groove 6, the second groove 7, and the third groove 8 are 1-1.5cm wide and 0.8-1.2cm deep. The two ends of the cavity are sealed and three corresponding U-shaped openings are provided. A 5-10cm metal plate extends from the bottom surface of each end of the first heating cavity 3. The first guide wheel 4 is installed at the right end of the first groove 6 and the middle part of the second groove 7. 4. The diameter is equal to the distance between the center lines of the first groove 6 and the second groove 7; a first guide wheel 4 of the same size is also provided between the second groove 7 and the third groove 8, and the first guide wheel 4 is driven by a coaxial motor 16 with adjustable speed control; the second heating plate 11 is an arc-shaped chrome-plated heating plate, and the edge of the second heating plate 11 is flush with the openings on both sides of the second heating cavity 9. The heating wire on the second heating plate 11 is attached to the heating plate and travels an S-stroke; the second heating plate 11 is 10-30cm wide, 5-8cm thick, and 80-10cm long. 20cm; along its length, the surface of the second heating plate 11 is a parabolic arc with an included angle of 5°-8°, chrome-plated and polished; it includes a stretching device system, which includes a holding roller group and a traction roller group; the holding roller group includes a power-driven main roller 13, a pressure roller 14 and a splitting roller 15 forming a pair with the main roller 13; the main roller 13 and the driven pressure roller 14 are made of fluorosilicone rubber; the splitting roller 15 has 8-10 wire grooves machined on its surface, the wire grooves are semi-circular, and their depth is between 0.2-0.5mm.

[0046] Step 1:

[0047] The puffing heating device 1 consists of the following components: ① Made of 1-1.5mm thick metal sheet welded together, with a 3mm thick insulation layer for heat preservation and energy saving. It contains aluminum silicate insulation cotton. The internal dimensions of the cavity are 80-120cm in length, 10-30cm in width, and 8-12cm in height. ② The sliding cover mechanism 12 is an independent part, capable of sliding open and closed. An external, suspended, push-pull metal slide rail is installed on the top surface. ③ The first heating cavity 3 and the slide rail are fixed to the metal wall panel. ④ A first heating plate 5 with a guide wire groove is placed inside the cavity. Its length and width dimensions match the internal dimensions of the cavity: 80-120cm in length, 10-30cm in width, and 5-8cm in height. It is placed at the bottom of the cavity, with the top open. Three U-shaped grooves, 2-3cm wide and 1-2cm long, are machined at equal intervals on the surface of the metal plate. ⑤ On both sides of the cavity, a metal plate with a thickness of 0.5-1mm is welded as a support. A torque motor is positioned and installed under the metal plate. Through the metal plate, on the right end, corresponding to the first groove 6 and the second groove 7 of the heating plate, a first guide wheel 4 coaxial with the coaxial motor 16 is installed. The first guide wheel 4 is smooth and has guide grooves on its edge. The arc angle (α) formed by the guide wheel disc of the first guide wheel 4 and the wire contact is ≤180°. The disc must be higher than the lower surface of the wire groove to achieve wire suspension and circulation. Similarly, on the left side of the cavity, corresponding to the second groove 7 and the third groove 8, a first guide wheel 4 is installed. The corresponding angles of the first guide wheel 4 and the wire are the same as those on the right end. The two first guide wheels 4 are linked and controlled synchronously.

[0048] Step Two:

[0049] Stretch heating device 2. ① The material and manufacturing process of the second heating chamber 9, as well as the design and process of the sliding cover mechanism 12, are the same as those of the expansion heating device 1. ② The difference lies in the inclusion of an internal electrically heated metal plate (i.e., the second electric heating plate 11), whose size matches the chamber. The surface needs to be machined into an arc-shaped parabolic surface with an arc angle (α) of 3-5°. The formed metal plate is chrome-plated to achieve a mirror-like finish. ③ Both ends of the chamber are designed with active wire guide wheels (i.e., the second wire guide wheel 10) identical to those of the expansion chamber. The difference is that the guide wheel discs here should ensure close contact between the wire and the surface of the heating plate for uniform heating. ④ This part of the device is also supported by the metal wall panel on the back and is linked with other parts.

[0050] Step 3:

[0051] The holding roller assembly consists of a main holding roller 13, a pressure roller 14, and a yarn separating roller 15, all mounted on a metal wall panel on a vertical surface. The main holding roller 13 is an electrically powered drive wheel, with a motor mounted on the back of the wall panel and driven coaxially with the drive wheel. The pressure roller 14 features a rotatable, lifting design; it is raised for yarn changing and stops at a fulcrum; during use, it is rotated down, its own weight pressing the yarn. The yarn separating roller 15's axis is mounted on the same horizontal line as the drive wheel, with a distance of 25cm between the two roller axes. The drive roller has a diameter of 15cm and a length of 25cm; the yarn separating roller 15 has a diameter of 8cm and a length of 25cm, and is engraved with 10 semi-circular grooves with a depth (R) of 0.2mm.

[0052] Step Four:

[0053] The drawing roller assembly is as follows: Similarly, the main drawing roller and the guide roller are mounted on the same metal wall panel. The main drawing roller is powered by a coaxial motor 16 installed behind the wall panel, serving as the driving roller, while the splitting roller 15 is the driven roller. The axes of the drawing roller and the splitting roller 15 are mounted on the same horizontal line, with a distance of 30cm between the center points of the two roller axes. The main drawing roller has a diameter of 15cm and a length of 25cm. The splitting roller 15 has a diameter of 8cm and a length of 25cm, and is engraved with 10 semi-circular grooves with a depth (R) of 0.2mm.

[0054] Step 5:

[0055] The front and rear air-cooling zones are essentially the pre- and post-air-cooling devices. Controllable air-coolers, with a power output of 1.5KW-3KW and two separate pipelines, are used to cool the continuous production line before the holding rollers and the drafting rollers in stages. This prevents the line from becoming deformed (flattened) due to its softness caused by heat carrying it into the rollers and being squeezed by the holding rollers or pulled by the drafting rollers. Air cooling primarily serves to solidify and shape the production line at different stages. The air coolers are common industrial refrigerant air coolers that can be adjusted and set according to room temperature changes. The air vents at both cooling points are designed as flat, rectangular vents, 20-30cm long and 2-3cm wide, positioned 5-10cm above the yarn, blowing air downwards.

[0056] Step Six:

[0057] Use a take-up device to take up the yarn, as per standard settings.

[0058] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A device for expanding and stretching circular-diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery, characterized in that, It includes a puffing heating device (1) and a stretching heating device (2) arranged in sequence; The puffing heating device (1) includes a first heating cavity (3), on both sides of the first heating cavity (3) are provided first wire guide wheels (4), and a first electric heating plate (5) is provided inside the first heating cavity (3). The first electric heating plate (5) is provided with wire guide grooves, and the wire guide grooves are provided with three identical grooves, namely the first groove (6), the second groove (7), and the third groove (8). The arc angle of the first wire guide wheel (4) is not greater than 180°. The parameters of the first heating cavity (3) are as follows: thickness 3-5mm, built-in heat insulation cotton, and inner cavity space width 10-30mm. The first heating plate (5) is placed inside the cavity from the bottom, with the length and width matching the size of the cavity space. The height is 5-8cm. The center point is the intersection of the middle part of the cavity height and the left and right three equal parts. A 1-2cm hole is set through the first heating cavity (3) to insert an electric heating rod as a heat source. The dimensions of the first groove (6), the second groove (7) and the third groove (8) are 1-1.5cm wide and 0.8-1.2cm deep. The two ends of the cavity are sealed with three corresponding U-shaped openings. The stretching heating device (2) includes a second heating cavity (9), with second guide wheels (10) on both sides of the second heating cavity (9). A second heating plate (11) is provided inside the second heating cavity (9). The second heating plate (11) is an arc-shaped chrome-plated heating plate. The edge of the second heating plate (11) is flush with the openings on both sides of the second heating cavity (9). The heating wires on the second heating plate (11) are attached to the heating plate and travel an S-shaped stroke. The second heating plate (11) is 10-30cm wide, 5-8cm thick, and 80-120cm long. In the length direction, the surface of the second heating plate (11) is a parabolic arc with an arc angle of 5°-8°. It is chrome-plated and polished. The device includes a stretching device system, which includes a gripping roller group and a drawing roller group. The gripping roller group includes a main roller (13) driven by a power, a pressure roller (14) forming a pair with the main roller (13), and a filament separating roller (15). The main roller (13) and the driven pressure roller (14) are made of fluorosilicone rubber. The filament separating roller (15) has 8-10 filament grooves on its surface. The filament grooves are semi-circular and their depth is between 0.2-0.5 mm. It includes a front air-cooling zone and a rear air-cooling zone, which are the front and rear air-cooling devices, to perform staged cooling of the continuous production line before the gripping roller group and the stretching roller group.

2. The expansion and stretching device for circular diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery as described in claim 1, characterized in that, The first heating cavity (3) and the second heating cavity (9) are both provided with a sliding cover mechanism (12).

3. The expansion and stretching device for circular diameter expanded polytetrafluoroethylene monofilament sewing thread for medical surgery as described in claim 1, characterized in that, Metal plates extending 5-10cm from the bottom surfaces of both ends of the first heating cavity (3) are installed at the right end of the first groove (6) and the middle part of the second groove (7). The diameter of the first guide wheel (4) is equal to the distance between the center lines of the first groove (6) and the second groove (7). A first guide wheel (4) of the same size is also provided between the second groove (7) and the third groove (8). The first guide wheel (4) is driven by a coaxial motor (16) with adjustable speed control.

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