Endoscope Insertion Tube Extrusion Process

Abstract

The invention relates to an endoscope insertion tube extrusion process, which uses TPU as a base material to prepare an endoscope insertion tube with better performance and quality, and the insertion tube includes an inner layer, an outer layer and an intermediate layer. The TPU inner layer and the TPU outer layer are both prepared by a single-screw extruder with different die sets; the stainless steel flat wire braided layer is obtained by braiding with a medical braiding machine; the extruded TPU inner layer mainly plays a lubricating role in the insertion tube; the stainless steel flat wire braided layer plays a supporting role in the insertion tube, and the tube body strength and overall toughness and elasticity can be changed by adjusting the specifications and density of the stainless steel flat wire; the extruded outer layer TPU is the outermost layer in the insertion tube, and mainly has the characteristics of high tension, high tensile force, strong toughness, lubricity and aging resistance. When the stainless steel flat wire braided layer is extruded through the outer layer, the TPU is melted at high temperature and then compounded with the inner layer and the outer layer to obtain a finished endoscope insertion tube. In addition, when preparing the endoscope insertion tube, the POM hard tube lining plays a supporting role.

Description

Technical Field

[0001] The invention relates to the technical field of endoscopes, and in particular to an endoscope insertion tube extrusion process. Background Art

[0002] The insertion tube of the existing endoscope is generally made of PEBAX, PE, PTFE materials, which have good lubrication performance and low friction coefficient, but also have the disadvantages of low strength and easy aging.

[0003] TPU has excellent high tension, high tensile force, strong and aging resistance characteristics. It is a mature environmentally friendly material. It has many excellent functions that other plastic materials cannot match, such as high strength, good toughness, wear resistance, cold resistance, oil resistance, water resistance, aging resistance, and weather resistance. Therefore, the insertion tube of the endoscope made of TPU as the main material has the characteristics of high tension, high tensile force, strong toughness, high lubricity and aging resistance, which greatly improves the quality and performance of the insertion tube of the endoscope. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide an endoscope insertion tube extrusion process, which can prepare an endoscope insertion tube with TPU material as the base material, and the insertion tube includes an inner layer, an outer layer and a middle layer; the inner layer and the outer layer are obtained by extruding the TPU material, and the middle layer is a flat wire stainless steel braided layer obtained by a medical braiding machine, and the stainless steel flat wire braided layer is arranged between the inner layer and the outer layer. When the middle layer is extruded through the outer layer, the TPU is melted at high temperature and compounded with the inner layer and the outer layer.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: the extrusion process comprises the following steps:

[0006] ① Extrusion of lined POM hard tube: Put the POM raw material into the extruder feeding device, and set it according to the characteristics of POM material: the temperature of main zone 1 is 160℃~170℃, the temperature of main zone 2 is 160℃~170℃, the temperature of main zone 3 is 160℃~170℃, the temperature of main flange is 165℃~175℃, the temperature of main head is 160℃~170℃, and the temperature of main mold is 165℃~175℃. Wait for the temperature of each area to rise to the set value, start the extruder, start the screw, adjust the screw speed to 3~4r / min, and clean the residual material in the screw and the die; after the residual material is cleaned, adjust the screw speed to 10-12r / min, observe the discharge of the die and adjust the uniformity of the discharge of the die. After adjusting the uniformity of the discharge of the die, the molten pom is extruded into the POM hard tube through the die, sizing sleeve, cooling device, traction device and winding device;

[0007] ② Extruding the inner TPU film: Put the TPU raw material into the oven for baking, the baking temperature is set to 90℃, the baking time is 2-3h, and then pour it into the extruder feeding device; replace the extruder head and die for extruding the inner TPU film; set the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head and main mold according to the characteristics of the TPU material, start the extruder, start the screw, adjust the screw speed, extrude the inner TPU film, and adjust the screw speed after extrusion to control the extrusion thickness of the TPU. Put the extruded inner TPU film on the outside of the extruded POM hard tube, and unwind the POM hard tube. The unwinding speed is synchronized with the extrusion speed of the inner TPU film;

[0008] ③ Weaving and winding of stainless steel flat wire: After the inner TPU inner membrane is installed on the outer surface of the POM hard tube, a medical braiding machine is used to weave and wind the stainless steel flat wire on the outer side of the inner TPU inner membrane to form a semi-finished insertion tube;

[0009] ④ Extrusion of outer layer TPU: Mix TPU raw material and masterbatch in a ratio of 100:6 and evenly mix them with the braided semi-finished insertion tube into an oven for baking. The baking temperature is set to 90°C. After baking for 2-3 hours, pour the mixed raw material into the extruder feeding device, and place the semi-finished insertion tube on the winding device in front of the extruder; replace the extruder head and die for extrusion of the outer layer TPU; reset the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head, main mold and spare oven according to the characteristics of TPU material, start the extruder, start the screw, adjust the screw speed, extrude the outer layer of TPU, adjust the screw speed to control the thickness of the outer layer TPU, compound the outer end of the extruded outer layer TPU on the end of the semi-finished insertion tube, start the winding device, control the extrusion speed and winding speed of the outer layer TPU synchronously so that the outer layer TPU is completely compounded on the outside of the semi-finished insertion tube, heat-melt the inner layer and outer layer TPU, and compound the inner layer and outer layer TPU with the middle stainless steel flat wire to make a finished insertion tube.

[0010] Preferably, the barrel length of the extruder is divided into three sections: main zone 1, main zone 2 and main zone 3, corresponding to the feeding section, compression section and metering section; the main head temperature is the temperature of the extruder head, the main mold temperature is the temperature of the mold in the head, and the main flange temperature is the temperature of the connecting flange between the extruder and the head; in step ②, when extruding the inner layer TPU inner film, set the temperature of main zone 1 to 200℃~220℃, the temperature of main zone 2 to 200℃~220℃, and the temperature of main zone 3 to 20 0℃~220℃, main flange temperature 200℃~220℃, main head temperature 200℃~220℃, main mold temperature 205℃~225℃; in step ④, when extruding the outer layer TPU, set the main zone 1 to 190℃~220℃, the main zone 2 to 190℃~220℃, the main zone 3 to 200℃~220℃, the main flange temperature to 190℃~220℃, the main head temperature to 190℃~220℃, and the main mold temperature to 190℃~225℃.

[0011] Preferably, in step ①, the POM hard tube is cooled by water, and the cooling device is a 3-meter vacuum cooling water tank, and the water temperature is controlled between 20 and 23°C by a fan.

[0012] Preferably, in step ①, after the extrusion of the POM hard tube is completed, the extruder screw, die, and die are cleaned of residual materials. The residual materials are first emptied and then deep cleaning is performed. For deep cleaning, 3-5 kg ​​of PC or PVC is put into the barrel to clean the residual materials in the extruder first. The screw speed is set to 20-50 r / min. The temperature during PVC cleaning is 150°C. After the cleaning is completed, the die, die, and screw are removed and the inside of the whole machine is cleaned. Sharp iron tools cannot be used during cleaning, and copper rods must be used for cleaning.

[0013] Preferably, in step ②, start the extruder, and after starting the screw, adjust the screw speed to 3-4r / min, and first clean the residual material in the screw and the die head; after the residual material is cleaned, adjust the screw speed to 10-12r / min, observe the discharge of the die and adjust the uniformity of the discharge of the die, and adjust the screw speed to 3-4r / min after the discharge of the die is uniform, and prepare for extrusion; the inner layer TPU inner film after extrusion is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

[0014] Preferably, in steps ①②④, a cutting device is provided in front of the winding device, and a contour detection device for real-time thickness detection is provided between the cutting device and the traction device.

[0015] Preferably, in step ③, on the medical braiding machine, the number of spindles is set to 16, the number of segments is 35PPI, the braiding angle is 122.92°, and the size of the stainless steel flat wire is: 0.05*0.127mm for 380C / 500C and 0.076*0.23mm for 580C; wherein, the number of segments can be adjusted according to actual conditions, and the braiding angle can be adjusted accordingly according to the number of segments.

[0016] Preferably, in step ④, start the extruder, start the screw, adjust the screw speed to 10-15r / min, and extrude the remaining material in the screw, die head and die; after cleaning the remaining material, adjust the screw speed to 10-12r / min, adjust the uniformity and color of the die discharge, and adjust the uniformity of the die discharge, pay attention to the flow state of the material, adjust the screw speed to 3-4r / min after the die discharge is uniform, and prepare for extrusion; the extruded outer layer TPU is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

[0017] Preferably, the inner diameter of the sizing sleeve is 0.8% to 1.2% larger than the inner diameter of the die.

[0018] Preferably, the extruder is a single-screw extruder, including a transmission system, a feeding system, an extrusion and plasticizing raw material system, a heating and cooling system, and an electrical control system; the extrusion and plasticizing raw material system includes a die, a barrel, a barrel screw and a connecting flange, the screw diameter of the barrel screw is 30 mm, and the aspect ratio of the barrel screw is 28:1, and a mold is provided in the die, and the mold includes a core and a die.

[0019] The present invention adopts the above technical scheme to prepare an endoscope insertion tube with TPU material as the base material, wherein the POM hard tube, TPU inner layer and TPU outer layer are prepared by a single screw extruder with different die; the stainless steel flat wire braided layer is woven by a medical braiding machine. The inner layer is made of the same TPU material as the outer layer. Since the TPU melt has high viscosity and stickiness, in order to ensure that the TPU melt is fully plasticized and at the same time minimize the viscosity of the product surface, a temperature distribution from low to high is adopted from the screw feeding to the metering section, and a descending temperature distribution is adopted from the die opening in the metering section. A lower die opening temperature can help improve the product strength.

[0020] In step ①, since TPU is thin and light and difficult to support, a POM hard tube lining with good surface lubricity and high hardness is first extruded before the inner layer of TPU is extruded to play a supporting role, and a layer of silicone oil is coated on the surface of the POM to facilitate subsequent separation from the insertion tube body. It should be noted here that the diameter of the inner lining POM hard tube is small, so the sizing sleeve shaping method is used for extrusion sizing. The POM tube is harder and cools faster. A vacuum device is provided at the shaping position to prevent the tube blank from shrinking.

[0021] In step ②, the extruded TPU inner layer mainly plays a lubricating role in the insertion tube.

[0022] In step ③, the stainless steel flat wire braided layer plays a supporting role in the insertion tube. The strength of the tube body and the overall toughness and elasticity can be changed by adjusting the specifications and density of the stainless steel flat wire.

[0023] In step ④, the extruded outer layer of TPU is the outermost layer in the insertion tube, and mainly has the characteristics of high tension, high pulling force, toughness, lubricity and aging resistance.

[0024] In addition, during the insertion and removal process of the tube, the overall toughness, elasticity, deflection and other properties of the tube body can be optimized by adjusting the specifications and models of the inner and outer TPU layers, and the specifications and density of the middle stainless steel flat wire.

[0025] In addition, when the extruder is just started, the screw speed usually needs to be adjusted to a lower level and the amount of material added is also less. After the material is extruded from the die, the speed can be slowly increased to increase the feed amount. At this time, the host current and melt pressure must be closely observed until the set speed is reached. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of a single-screw extruder.

[0027] Figure 2 Extrusion line for endoscope insertion tube.

[0028] Figure 3 for Figure 2 Schematic top view of . DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] Endoscope insertion tube extrusion process, using Figures 1 to 3 The device in implements the following steps:

[0035] ① Extrusion of lined POM hard tube: Put the POM raw material into the extruder feeding device, and set it according to the characteristics of POM material: the temperature of main zone 1 is 160℃~170℃, the temperature of main zone 2 is 160℃~170℃, the temperature of main zone 3 is 160℃~170℃, the temperature of main flange is 165℃~175℃, the temperature of main head is 160℃~170℃, and the temperature of main mold is 165℃~175℃. Wait for the temperature of each area to rise to the set value, start the extruder, start the screw, adjust the screw speed to 3~4r / min, and clean the residual material in the screw and the die; after the residual material is cleaned, adjust the screw speed to 10-12r / min, observe the discharge of the die and adjust the uniformity of the discharge of the die. After adjusting the uniformity of the discharge of the die, the molten pom is extruded into the POM hard tube through the die, sizing sleeve, cooling device, traction device and winding device;

[0036] ② Extruding the inner TPU film: Put the TPU raw material into the oven for baking, the baking temperature is set to 90℃, the baking time is 2-3h, and then pour it into the extruder feeding device; replace the extruder head and die for extruding the inner TPU film; set the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head and main mold according to the characteristics of the TPU material, start the extruder, start the screw, adjust the screw speed, extrude the inner TPU film, and adjust the screw speed after extrusion to control the extrusion thickness of the TPU. Put the extruded inner TPU film on the outside of the extruded POM hard tube, and unwind the POM hard tube. The unwinding speed is synchronized with the extrusion speed of the inner TPU film;

[0037] ③ Weaving and winding of stainless steel flat wire: After the inner TPU inner membrane is installed on the outer surface of the POM hard tube, a medical braiding machine is used to weave and wind the stainless steel flat wire on the outer side of the inner TPU inner membrane to form a semi-finished insertion tube;

[0038] ④ Extrusion of outer layer TPU: Mix TPU raw material and masterbatch in a ratio of 100:6 and evenly mix them with the braided semi-finished insertion tube into an oven for baking. The baking temperature is set to 90°C. After baking for 2-3 hours, pour the mixed raw material into the extruder feeding device, and place the semi-finished insertion tube on the winding device in front of the extruder; replace the extruder head and die for extrusion of the outer layer TPU; reset the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head, main mold and spare oven according to the characteristics of TPU material, start the extruder, start the screw, adjust the screw speed, extrude the outer layer of TPU, adjust the screw speed to control the thickness of the outer layer TPU, compound the outer end of the extruded outer layer TPU on the end of the semi-finished insertion tube, start the winding device, control the extrusion speed and winding speed of the outer layer TPU synchronously so that the outer layer TPU is completely compounded on the outside of the semi-finished insertion tube, heat-melt the inner layer and outer layer TPU, and compound the inner layer and outer layer TPU with the middle stainless steel flat wire to make a finished insertion tube.

[0039] Furthermore, the barrel length of the extruder is divided into three sections: main zone 1, main zone 2 and main zone 3, corresponding to the feeding section, compression section and metering section; the main head temperature is the temperature of the extruder head, the main mold temperature is the temperature of the mold in the head, and the main flange temperature is the temperature of the connecting flange between the extruder and the head; in step ②, when extruding the inner layer TPU inner film, set the temperature of main zone 1 to 200℃~220℃, the temperature of main zone 2 to 200℃~220℃, and the temperature of main zone 3 to 20 0℃~220℃, main flange temperature 200℃~220℃, main head temperature 200℃~220℃, main mold temperature 205℃~225℃; in step ④, when extruding the outer layer TPU, set the main zone 1 to 190℃~220℃, the main zone 2 to 190℃~220℃, the main zone 3 to 200℃~220℃, the main flange temperature to 190℃~220℃, the main head temperature to 190℃~220℃, and the main mold temperature to 190℃~225℃.

[0040] Furthermore, in step ①, the POM hard tube is cooled by water, and the cooling device is a 3-meter vacuum cooling water tank, and the water temperature is controlled between 20 and 23°C by a fan.

[0041] Furthermore, in step ①, after the extrusion of the POM hard tube is completed, the extruder screw, die, and die are cleaned of residual materials. The residual materials are first emptied and then deep cleaning is performed. For deep cleaning, 3-5 kg ​​of PC or PVC is put into the barrel to clean the residual materials in the extruder first. The screw speed is set to 20-50 r / min. The temperature during PVC cleaning is about 150°C. After the cleaning is completed, the die, die, and screw are removed and the inside of the whole machine is cleaned. Do not use sharp iron tools during cleaning. Softer materials such as copper rods are required for cleaning.

[0042] Furthermore, in step ②, the extruder is started, and after the screw is started, the screw speed is also adjusted to 3-4r / min, and the residual material in the screw and the die head is cleaned first; after the residual material is cleaned, the screw speed is adjusted to 10-12r / min, the discharge of the die is observed and the uniformity of the discharge of the die is adjusted, and after the discharge of the die is uniform, the screw speed is adjusted to 3-4r / min, and extrusion is prepared; the inner layer TPU inner film after extrusion is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

[0043] Furthermore, in steps ①②④, a cutting device is provided in front of the winding device, and a contour detection device for real-time thickness detection is also provided between the cutting device and the traction device.

[0044] Furthermore, in step ③, on the medical braiding machine, the number of spindles is set to 16, the number of segments is set to 35PPI, the braiding angle is 122.92°, and the size of the stainless steel flat wire is: 0.05*0.127mm for 380C / 500C and 0.076*0.23mm for 580C; wherein, the number of segments can be adjusted according to actual conditions, and the braiding angle can be adjusted accordingly according to the number of segments.

[0045] Further, in step ④, start the extruder, start the screw, adjust the screw speed to 10-15r / min, and extrude the remaining material in the screw, die head and die; after cleaning the remaining material, adjust the screw speed to 10-12r / min, adjust the uniformity and color of the die discharge, and adjust the uniformity of the die discharge, pay attention to the flow state of the material, adjust the screw speed to 3-4r / min after the die discharge is uniform, and prepare for extrusion; the extruded outer layer TPU is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

[0046] Furthermore, the inner diameter of the sizing sleeve is 0.8% to 1.2% larger than the inner diameter of the die.

[0047] Furthermore, the extruder is a single-screw extruder, including a transmission system, a feeding system, an extrusion and plasticizing raw material system, a heating and cooling system, and an electrical control system; the extrusion and plasticizing raw material system includes a head, a barrel, a barrel screw and a connecting flange, the screw diameter of the barrel screw is 30 mm, and the length-to-diameter ratio of the barrel screw is 28:1. A mold is provided in the head, and the mold includes a core and a die.

[0048] In this specific embodiment, an endoscope insertion tube with better performance and quality is prepared by using TPU as a base material, and the insertion tube includes an inner layer, an outer layer and an intermediate layer. The extruded TPU inner layer mainly plays a lubricating role in the insertion tube; the stainless steel flat wire braided layer plays a supporting role in the insertion tube, and the strength of the tube body and the overall toughness and elasticity can be changed by adjusting the specifications and density of the stainless steel flat wire; the extruded outer layer TPU is the outermost layer in the insertion tube, and mainly has the characteristics of high tension, high tensile force, strong toughness, lubricity and aging resistance. The stainless steel flat wire braided layer is arranged between the inner layer TPU and the outer layer TPU, and when the intermediate layer is extruded through the outer layer, the TPU is melted at high temperature and composited with the inner layer and the outer layer.

[0049] In addition, since TPU is thin and light and difficult to support, a POM hard tube lining with good surface lubricity and high hardness is first extruded before the inner layer of TPU is extruded to play a supporting role, and a layer of silicone oil is coated on the surface of the POM to facilitate subsequent separation from the insertion tube body. It should be noted here that the diameter of the inner lining POM hard tube is small, so the sizing sleeve shaping method is used for extrusion sizing. The POM tube is harder and cools faster. A vacuum device is provided at the shaping position to prevent the tube blank from shrinking.

[0050] The POM hard tube, TPU inner layer and TPU outer layer are all prepared by a single screw extruder with different die sets; the stainless steel flat wire braided layer is woven by a medical braiding machine. After the four layers of tubes are prepared through four steps, the POM hard tube is removed, and the remaining three layers are the new endoscope insertion tube with better performance.

[0051] When preparing the inner and outer TPU tube layers, since the TPU melt has great viscosity and stickiness, in order to ensure that the TPU melt is fully plasticized while minimizing the viscosity of the product surface, a temperature distribution from low to high is adopted from the screw feeding to the metering section, and a descending temperature distribution is adopted from the die to the metering section. A lower die temperature can help improve product strength.

[0052] In addition, during the insertion and removal process of the tube, the overall toughness, elasticity, deflection and other properties of the tube body can be optimized by adjusting the specifications and models of the inner and outer TPU layers, and the specifications and density of the middle stainless steel flat wire.

[0053] In addition, when the extruder is just started, the screw speed usually needs to be adjusted to a lower level and the amount of material added is also less. After the material is extruded from the die, the speed can be slowly increased to increase the feed amount. At this time, the host current and melt pressure must be closely observed until the set speed is reached.

[0054] Figure 2The figure shows a 10-meter extrusion line, which includes a single screw extruder 1, a connecting flange 8, a die head 7, a three-meter vacuum cooling water tank 2, a diameter gauge 3, a medical traction machine 4, a tension frame 5, and a double-disc winding 6. It should be noted that the sizing sleeve, cutting device, and contour detection equipment are not shown here.

[0055] It should also be noted that the die in the mold is used to shape the outer surface of the product, and the core rod is used to shape the inner surface of the pipe.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0057] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. Endoscope insertion tube extrusion process, characterized by: The extrusion process includes the following steps: ① Extrusion of lined POM hard tube: Put the POM raw material into the extruder feeding device, and set it according to the characteristics of POM material: the temperature of main zone 1 is 160℃~170℃, the temperature of main zone 2 is 160℃~170℃, the temperature of main zone 3 is 160℃~170℃, the temperature of main flange is 165℃~175℃, the temperature of main head is 160℃~170℃, and the temperature of main mold is 165℃~175℃. Wait for the temperature of each area to rise to the set value, start the extruder, start the screw, adjust the screw speed to 3~4r / min, and clean the residual material in the screw and the die; after the residual material is cleaned, adjust the screw speed to 10-12r / min, observe the discharge of the die and adjust the uniformity of the discharge of the die. After adjusting the uniformity of the discharge of the die, the molten pom is extruded into the POM hard tube through the die, sizing sleeve, cooling device, traction device and winding device; ② Extruding the inner TPU film: Put the TPU raw material into the oven for baking, the baking temperature is set to 90℃, the baking time is 2-3h, and then pour it into the extruder feeding device; replace the extruder head and die for extruding the inner TPU film; set the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head and main mold according to the characteristics of the TPU material, start the extruder, start the screw, adjust the screw speed, extrude the inner TPU film, and adjust the screw speed after extrusion to control the extrusion thickness of the TPU. Put the extruded inner TPU film on the outside of the extruded POM hard tube, and unwind the POM hard tube. The unwinding speed is synchronized with the extrusion speed of the inner TPU film; ③ Weaving and winding of stainless steel flat wire: After the inner TPU inner membrane is installed on the outer surface of the POM hard tube, a medical braiding machine is used to weave and wind the stainless steel flat wire on the outer side of the inner TPU inner membrane to form a semi-finished insertion tube; ④ Extrusion of outer layer TPU: Mix TPU raw material and masterbatch in a ratio of 100:6 and evenly mix them with the braided semi-finished insertion tube into an oven for baking. The baking temperature is set to 90°C. After baking for 2-3 hours, pour the mixed raw material into the extruder feeding device, and place the semi-finished insertion tube on the winding device in front of the extruder; replace the extruder head and die for extrusion of the outer layer TPU; reset the temperature of the main zone 1, main zone 2, main zone 3, main flange, main head, main mold and spare oven according to the characteristics of TPU material, start the extruder, start the screw, adjust the screw speed, extrude the outer layer of TPU, adjust the screw speed to control the thickness of the outer layer TPU, compound the outer end of the extruded outer layer TPU on the end of the semi-finished insertion tube, start the winding device, control the extrusion speed and winding speed of the outer layer TPU synchronously so that the outer layer TPU is completely compounded on the outside of the semi-finished insertion tube, heat-melt the inner layer and outer layer TPU, and compound the inner layer and outer layer TPU with the middle stainless steel flat wire to make a finished insertion tube.

2. The endoscope insertion tube extrusion process according to claim 1, characterized in that: The barrel length of the extruder is divided into three sections: main zone 1, main zone 2 and main zone 3, which correspond to the feeding section, compression section and metering section; the main head temperature is the temperature of the extruder head, the main mold temperature is the temperature of the mold inside the head, and the main flange temperature is the temperature of the connecting flange between the extruder and the head; in step ②, when extruding the inner layer TPU inner film, set the temperature of main zone 1 to 200℃~220℃, the temperature of main zone 2 to 200℃~220℃, and the temperature of main zone 3 to 200℃~ 220℃, main flange temperature 200℃~220℃, main head temperature 200℃~220℃, main mold temperature 205℃~225℃; in step ④, when extruding the outer layer TPU, set the main zone 1 to 190℃~220℃, the main zone 2 to 190℃~220℃, the main zone 3 to 200℃~220℃, the main flange temperature to 190℃~220℃, the main head temperature to 190℃~220℃, and the main mold temperature to 190℃~225℃.

3. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In step ①, the POM hard tube is cooled by water, and the cooling device is a 3-meter vacuum cooling water tank, and the water temperature is controlled between 20 and 23°C by a fan.

4. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In step ①, after the extrusion of the POM hard tube is completed, the extruder screw, die, and die are cleaned of residual materials. The residual materials are first emptied and then deep cleaning is performed. For deep cleaning, 3-5kg of PC or PVC is put into the barrel to clean the residual materials in the extruder first. The screw speed is set to 20-50r / min. The temperature during PVC cleaning is 150℃. After the cleaning is completed, the die, die, and screw are removed and the inside of the whole machine is cleaned. Do not use sharp iron tools during cleaning, and use copper rods for cleaning.

5. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In step ②, start the extruder, after starting the screw, it is also necessary to adjust the screw speed to 3-4r / min, first clean the residual material in the screw and the die; after the residual material is cleaned, adjust the screw speed to 10-12r / min, observe the discharge of the die and adjust the uniformity of the discharge of the die, and adjust the screw speed to 3-4r / min after the discharge of the die is uniform, and prepare for extrusion; the inner layer TPU inner film after extrusion is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

6. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In steps ①②④, a cutting device is provided in front of the winding device, and a contour detection device for real-time thickness detection is provided between the cutting device and the traction device.

7. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In step ③, on the medical braiding machine, set the number of spindles to 16, the number of segments to 35PPI, the braiding angle to 122.92°, the size of the stainless steel flat wire: 380C / 500C uses 0.05*0.127mm, 580C uses 0.076*0.23mm; among them, the number of segments can be adjusted according to actual conditions, and the braiding angle can be adjusted accordingly according to the number of segments.

8. The endoscope insertion tube extrusion process according to claim 1, characterized in that: In step ④, start the extruder, start the screw, adjust the screw speed to 10-15r / min, and extrude the remaining material in the screw, die head and die; after cleaning the remaining material, adjust the screw speed to 10-12r / min, adjust the uniformity and color of the die discharge, and adjust the uniformity of the die discharge, pay attention to observe the flow state of the material, adjust the screw speed to 3-4r / min after adjusting the die discharge to uniform, and prepare for extrusion; the extruded outer layer TPU is extruded through the die, sizing sleeve, cooling water tank, traction device and winding device.

9. The endoscope insertion tube extrusion process according to claim 1, characterized in that: The inner diameter of the sizing sleeve is 0.8% to 1.2% larger than the inner diameter of the die.

10. The endoscope insertion tube extrusion process according to claim 1, characterized in that: The extruder is a single-screw extruder, including a transmission system, a feeding system, an extrusion and plasticizing raw material system, a heating and cooling system, and an electrical control system; the extrusion and plasticizing raw material system includes a die, a barrel, a barrel screw, and a connecting flange, the screw diameter of the barrel screw is 30 mm, and the length-to-diameter ratio of the barrel screw is 28:

1. A mold is provided in the die, and the mold includes a core and a die.

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