Hard pipe body forming device and preparation method thereof

Abstract

According to the hard pipe body forming device and the preparation method thereof, a pre-sizing part is arranged to be of a split structure with a front part and a rear part, the front section of a sizing sleeve is located in a constant-temperature water tank and has a common sizing effect, and auxiliary hole sets which are densely distributed are formed in the rear section of the sizing sleeve in the axial direction and located in a true hole water tank; the pre-cooling water tank and the cooling water tank are arranged in a matched manner, so that the phenomena that the surface of the pipe body is rough and the outer diameter of the pipe body is uneven are improved; the problems of troublesome traction and material blockage of the sizing sleeve in the extrusion process are solved, the problem of material waste in the extrusion process is solved, the product quality of the hard conduit is improved, the production efficiency is improved, the production cost is reduced, and the operation is simple and convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of hard pipe body production, and in particular relates to a hard pipe body forming device and a preparation method thereof. Background Art

[0002] With the continuous progress of modern medicine, various advanced diagnosis and treatment technologies have gradually become popular, such as cardiovascular interventional treatment, neurovascular interventional treatment, endoscopic examination and surgery, etc. These technologies require the use of high-quality medical catheters to assist in completion, which has promoted the development of medical catheter technology and also put forward higher requirements on the performance and quality of hard material catheters. For example, in cardiovascular interventional surgery, a catheter with a certain hardness and flexibility is required to accurately reach the lesion site and perform treatment.

[0003] In minimally invasive surgery, medical catheters are indispensable tools that are used to introduce instruments, deliver drugs, and drain fluids. In order to meet the needs of minimally invasive surgery, medical catheters need to have smaller outer diameters, better flexibility, and higher strength, and the requirements for hard material catheters are getting higher and higher.

[0004] Therefore, high-quality, high-precision hard material catheter molding is an urgent problem to be solved. At present, only the research on extruders and extruder heads can solve the melting effect of hard polymer materials, but the sizing and cooling cannot be accurately controlled, the molding is relatively poor, the thickness of the extruded tube is uneven during the molding process, and it is easy to break the tube and block the material during the extrusion process. Since hard materials will harden after cooling, the tube body is prone to blockage when passing through an ordinary sizing sleeve. If it directly enters an ordinary water tank, the tube body will harden quickly. Vacuuming or blowing will have no effect on the tube body, but it will have a great impact on subsequent secondary processing and cannot meet product needs.

[0005] The utility model with announcement number CN219947178U discloses a plastic hard tube extruder. The key points of its technical solution include an extruder body with a frame at the bottom, a feeding port and an extrusion tube are respectively arranged on both sides of the frame, a pushing mechanism is arranged in the frame, and a plurality of heating tennis ball covers arranged at intervals are connected to the inside of the frame. A heating ring embedded in the inner wall of the extruder body is arranged between two adjacent heating tennis ball covers. By arranging the heating tennis ball cover instead of the heating bucket, each plastic passing through a heating tennis ball cover is heated twice, thereby improving the heating effect. At the same time, a heating ring embedded in the extruder body is arranged between two adjacent heating tennis ball covers to heat the plastic on the outside.

[0006] The utility model with announcement number CN216001357U discloses a plastic hard tube extrusion processing device, the key points of its technical solution include a barrel, a driving device arranged at the top of the barrel, a driving shaft arranged inside the barrel and transmission-connected to the driving device, a discharge port arranged at the bottom of the barrel, and a feed hopper arranged on the surface of the barrel near the top and connected to the inside of the barrel. The inside of the barrel is provided with a feeding area, a centralized heating area and a heating and heat preservation area from top to bottom, and a heating hopper movably sleeved on the surface of the driving shaft is provided at the junction of the feeding area, the centralized heating area and the heating and heat preservation area.

[0007] The above two technical solutions both improve the melting effect of hard materials from the extrusion equipment, but do not control the subsequent molding, which will lead to problems such as uneven size, large ovality, and rough surface after extrusion.

[0008] The utility model with announcement number CN221809579U discloses a vacuum sizing device for small pipe extrusion, and its technical solution key points include a sizing sleeve, an extrusion channel and a vacuum channel; the extrusion channel is through-opened on the sizing sleeve, and the extrusion channel also includes a feed port located at one end of the sizing sleeve, and a discharge port located at the other end of the sizing sleeve; the vacuum channel is through-opened on the side wall of the sizing sleeve and is connected with the extrusion channel; the sizing sleeve is divided into an upper sleeve flap and a lower sleeve flap, and during the sizing sleeve processing, the grooves on the lower sleeve flap and the upper sleeve flap can be polished respectively; however, it only describes the structure of the sizing device, which mainly solves the problems of difficulty in grinding and polishing the inner hole of the vacuum sizing sleeve of a pipe with a smaller diameter, and the inconvenience of subsequent maintenance of the inner hole. This sizing sleeve can be used for ordinary polymer materials, but the sizing effect for hard polymer materials is not ideal.

[0009] The current problems with rigid tube extrusion are: 1. Due to the poor fluidity of hard plastic extrusion, uneven tube thickness, rough surface, broken tube, blockage and other phenomena are prone to occur during the extrusion process, which affects the quality, appearance and production efficiency of the product.

[0010] 2. Hard materials will harden after cooling. The pipe body is prone to blockage when passing through an ordinary sizing sleeve, and will harden quickly when directly entering an ordinary water tank. Vacuuming or blowing will have no effect on the inner and outer diameters and ovality of the pipe body, and the consistency of the inner and outer diameters and ovality of the product cannot be guaranteed.

[0011] 3. The traditional sizing sleeve is an integrated sizing sleeve with relatively dispersed and large apertures. The high vacuum degree will cause uneven pipe body.

[0012] In view of the above problems, the present invention provides a method for forming a hard tube, which can achieve high precision of the hard tube and high uniformity of the microscopic morphology of the material. Summary of the invention

[0013] The purpose of the present invention is to provide a hard pipe body forming device and a preparation method thereof to solve the problems of sizing sleeve blockage and pipe pulling difficulty in view of the above-mentioned deficiencies in the prior art.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is: A hard pipe body forming device comprises an extruder part, a predetermined diameter part, a cooling part, a traction ultrasonic closed loop and a cutting part, wherein the extruder part comprises an extruder and a die head and an extrusion die installed on the extruder. The predetermined sizing part comprises a sizing sleeve upper body and a sizing sleeve lower body which are separated and assembled, and a sizing sleeve front fixing plate and a sizing sleeve rear fixing plate which are sleeved on the two bodies at intervals, and the sizing sleeve front fixing plate and the sizing sleeve rear fixing plate divide it into a sizing sleeve front section and a sizing sleeve rear section, and the sizing sleeve front fixing plate is sleeved on the head end of the sizing sleeve front section and fastens the upper and lower bodies by fixing bolts arranged in the radial direction; The front section of the sizing sleeve is provided with a group of sparsely arranged sizing holes along the axial direction, and each group of sizing holes is provided with a plurality of sizing holes along the circumferential direction. The rear section of the sizing sleeve is provided with a group of auxiliary holes densely arranged along the axial direction, and each group of auxiliary holes is provided with a plurality of auxiliary holes along the circumferential direction, and the diameter of the auxiliary holes is much smaller than the diameter of the sizing holes; The cooling part includes a pre-cooling water tank and a cooling water tank, and the pre-cooling water tank includes a constant temperature water tank and a vacuum water tank, the front section of the sizing sleeve is located in the constant temperature water tank, and the rear section of the sizing sleeve is located in the vacuum water tank; The tube extruded through the sizing sleeve is pre-cooled in a constant temperature water tank and then enters a vacuum water tank. It is then shaped in a cooling water tank under the traction of a traction machine placed at the rear end of the vacuum water tank. It is then extruded through a traction ultrasonic closed loop and cut into the required length by the cutting section.

[0015] The front fixing plate of the sizing sleeve is fixed on the water baffle plate arranged at the front end of the constant temperature water tank, and the rear fixing plate of the sizing sleeve is arranged between the two side walls of the constant temperature water tank and the vacuum water tank.

[0016] The vacuum water tank is fixed on a provided water tank rack, and the constant temperature water tank is fixed on the vacuum water tank and the temperature is controlled by a provided constant temperature sensor and a temperature controller.

[0017] The sizing hole groups are provided with 1 to 6 groups, and the sizing hole diameters are 1 to 3 mm; The auxiliary hole groups are provided with 10 to 30 groups, and the auxiliary hole diameters are 0.05 to 0.2 mm.

[0018] A method for preparing a hard pipe body forming device comprises the following steps: (1) Dry the material and select the mold and corresponding extrusion parameters according to the material; (2) Extrusion Install the die and mandrel that are suitable for the size of the tube body, and calibrate the positions of the die and mandrel. Then add the dried material into the barrel, and extrude the molten material through the die by pressurizing the screw. (3) Install the sizing part and sizing sleeve Install and fix the upper and lower bodies of the sizing sleeve, and adjust the distance between them and the rear die; (4) Pre-cooling water tank The tube body enters the constant temperature water tank for pre-cooling, and the temperature of the constant temperature water tank is maintained at 28-30℃, and then enters the vacuum water tank; (5) Cooling and shaping The traction machine pulls the tube embryo into the cooling water tank for shaping; (6) Traction ultrasonic closed loop Turn on the traction machine, set the traction speed, close the loop and adjust the traction speed in real time; (7) Cutting and forming Cut into appropriate length according to product usage requirements.

[0019] In step (1), if the material is TPU or PA pellets, it is dried at 80-100°C for 2-6 hours; If the material is PVC or PP granules, drying is not required.

[0020] In step (1), if PVC pellets are used as the material, the size of the die core rod of the mold needs to be 1.0-1.4 times the wall thickness of the tube body; If TPU pellets are used as the material, the size of the die core rod of the mold must be 1.2-1.5 times the wall thickness of the tube; If PP granules are used as the material, the size of the die core rod of the mold must be 1.0-1.2 times the wall thickness of the tube; If PA granules are used as the material, the size of the die core rod of the mold must be 1.4-3.0 times the wall thickness of the tube.

[0021] In step (3), if PVC pellets are used as the material, the length of the sizing sleeve must be 15-33 times the outer diameter of the tube; If TPU pellets are used as the material, the length of the sizing sleeve must be 14-22 times the outer diameter of the tube; If PP granules are used as the material, the length of the sizing sleeve must be 14-22 times the outer diameter of the tube; If PA granules are used as the material, the length of the sizing sleeve must be 12-23 times the outer diameter of the tube.

[0022] The temperature of the constant temperature water tank is 28-30°C, and the water temperature in the cooling water tank is 10°C-15°C.

[0023] The vacuum degree of the vacuum water tank is 23Kpa-65Pkpa, and the top cover of the vacuum water tank is provided with a glass baffle for sealing.

[0024] The beneficial effects of the present invention are: (1) The present invention discloses a hard tube forming device and a preparation method thereof. The predetermined sizing portion is set as a split structure with a front and a rear part. The front section of the sizing sleeve is located in a constant temperature water tank for a common sizing effect. The rear section of the sizing sleeve has a group of auxiliary holes densely arranged along the axial direction and is located in a true hole water tank. The coordinated arrangement of the pre-cooling water tank and the cooling water tank improves the rough surface of the tube body and the uneven outer diameter of the tube body. It also improves the problems of traction trouble, sizing sleeve blockage, and material waste during extrusion, thereby improving the product quality of the hard conduit, improving production efficiency, reducing production costs, and making the operation simple and convenient.

[0025] (2) The present invention solves the problem of large ovality and uneven size of hard conduits. The diameter is determined by a novel split-type predetermined diameter device in two parts, and secondary shaping is performed by vacuuming in a constant temperature water tank and a vacuum water tank. This method improves product quality and the qualified rate of subsequent processing.

[0026] (3) The present invention solves the problem of rough surface of hard conduits. The original sizing sleeve has a large aperture and a relatively scattered hole distribution. When the water pressure is unstable, it will cause the surface of the tube to be rough. The new sizing sleeve has a front and rear two-part structure and a design of small holes in the rear half, which can solve the problem of rough surface and reduce the scrap rate during the extrusion process, thereby saving costs.

[0027] (4) The split sizing sleeve can solve the problems of sizing sleeve blockage and difficulty in pulling the pipe, and the water flow is uniform and the surface of the pipe body is smooth; the pre-cooling water tank proposed in the patent of this invention can pre-cool the pipe body instead of rapid cooling, which can make the pipe body size uniform and the conduit more round. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the predetermined diameter portion of the present invention; Figure 2 It is a cross-sectional schematic diagram of the pre-cooling water tank of the present invention; Figure 3 It is a structural schematic diagram of a constant temperature water tank of the present invention; Figure 4 It is a schematic diagram of the assembly of the predetermined diameter portion and the pre-cooling water tank. DETAILED DESCRIPTION

[0029] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0030] See also Figures 1 to 4 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0031] The present invention provides a hard tube forming device and a preparation method thereof, such as Figures 1 to 4 shown.

[0032] A hard pipe body forming device comprises an extruder part, a predetermined diameter part, a cooling part, a traction ultrasonic closed loop and a cutting part, wherein the extruder part comprises an extruder and a die head and an extrusion die installed on the extruder.

[0033] The predetermined sizing portion includes a split and assembled sizing sleeve upper body 4, a sizing sleeve lower body 5, and a sizing sleeve front fixing plate 2 and a sizing sleeve rear fixing plate 3 which are sleeved thereon at intervals, and the sizing sleeve front fixing plate 2 and the sizing sleeve rear fixing plate 3 divide it into a sizing sleeve front section 31 and a sizing sleeve rear section 32, and the sizing sleeve front fixing plate 2 is sleeved on the head end of the sizing sleeve front section 31 and fastened to the upper and lower bodies by fixing bolts 1 arranged along the radial direction.

[0034] The front section 31 of the sizing sleeve is provided with sparsely arranged sizing holes in the axial direction, and each sizing hole group is provided with a plurality of sizing holes in the circumferential direction; there are 1 to 6 sizing hole groups, each group is provided with 6 to 10 sizing holes in the circumferential direction, and the diameter of the sizing holes is 1 to 3 mm.

[0035] The rear section 32 of the sizing sleeve is provided with auxiliary hole groups densely arranged along the axial direction, and each auxiliary hole group is provided with multiple auxiliary holes along the circumferential direction, and the aperture of the auxiliary holes is much smaller than the aperture of the sizing holes; preferably, there are 10 to 30 auxiliary hole groups, each group is provided with 16 to 20 auxiliary holes along the circumferential direction, and the aperture of the auxiliary holes is 0.05 to 0.2 mm.

[0036] The cooling part includes a pre-cooling water tank and a cooling water tank, and the pre-cooling water tank includes a constant temperature water tank 13 and a vacuum water tank 17, and the water temperature in the vacuum water tank 17 is consistent with that in the constant temperature water tank 13, the front section 31 of the sizing sleeve is located in the constant temperature water tank 13, and the rear section 32 of the sizing sleeve is located in the vacuum water tank 17. After the sizing sleeve is locked, the vacuum degree of the vacuum water tank 17 can be maintained.

[0037] During installation, after the pipe body is pulled, it passes through the lower body 5 of the sizing sleeve and the front fixing plate 2 and the rear fixing plate 3 of the sizing sleeve. After the pipe body is stable, the upper body 4 of the sizing sleeve is installed on the front fixing plate 2 and the rear fixing plate 3 of the sizing sleeve. After being installed in place, the fixing bolts 1 of the sizing sleeve are installed on the front fixing plate 2 of the sizing sleeve to fix it. The front fixing plate 2 of the sizing sleeve is fixed on the water baffle 14 provided at the front end of the constant temperature water tank 13, and the rear fixing plate 3 of the sizing sleeve is arranged on the side wall between the constant temperature water tank 13 and the vacuum water tank 17.

[0038] For the convenience of operation, the vacuum water tank 17 is fixed on the provided water tank frame 22 , and the constant temperature water tank 13 is fixed on the vacuum water tank 17 and the temperature is controlled by the provided constant temperature sensor 10 and the temperature controller 11 .

[0039] More specifically, the vacuum water tank 17 is fixed to the water tank frame 22 by welding, the constant temperature water tank 13 is fixed to the vacuum water tank 17 by fixing screws 16, the sizing sleeve device is installed on the water baffle 14, the water baffle 14 is fixed to the constant temperature water tank 13 by water baffle screws 15, the temperature control protection box 12 is welded and fixed to the vacuum water tank 17, the glass baffle 18, the glass fixing frame 19, and the movable frame 20 are fixed to the vacuum water tank 17 by glass fixing screws 21 and serve as the upper cover of the vacuum water tank 17 to play a sealing role.

[0040] The tube extruded through the sizing sleeve is pre-cooled in the constant temperature water tank 13 and then enters the vacuum water tank 17. It is then shaped in the cooling water tank under the traction of the traction machine placed at the rear end of the vacuum water tank 17, and then extruded through the traction ultrasonic closed loop and cut into the required length by the cutting part.

[0041] Cooling water tank, according to the size of the tube body, select a cooling water tank with a length of 4m~6m, and the cooling water tank is connected to the refrigerator. Before extrusion, add a certain amount of purified water to the water tank of the cooling water tank, adjust the cooling water temperature to 10℃-15℃, and the control accuracy is ±2℃. The water is cooled by the cooling system of the refrigerator, and then the cooling water is sent to the cooling water tank by the water pump. Then the tube embryo is pulled into the cooling water tank, and the tube embryo is immersed in the cooling water to reduce the temperature of the tube embryo and achieve the shaping effect.

[0042] Traction ultrasonic closed loop, closed loop extrusion, real-time deviation correction and adjustment of traction speed; the laser detection probe measures the outer diameter of the tube in real time, combined with the inner diameter and wall thickness measured by the ultrasonic detection probe, the closed loop control system compares the collected signal with the set value. When there is a deviation, the closed loop control system will convert the traction signal into an analog quantity and send out a deviation signal, and use this signal to adjust the traction speed to ensure the stability of tube extrusion.

[0043] The original sizing sleeve is usually a whole cylinder. Since the outer diameter of the tube body is very different from the inner size of the sizing sleeve, it is not easy to pass through the sizing sleeve after the tube body is extruded, and it is easy to block the material, and it is difficult to pull the tube, and it is easy to break the tube. However, by dividing it into the front section 31 of the sizing sleeve and the rear section 32 of the sizing sleeve, the problems of blocking the sizing sleeve and the difficulty of pulling the tube are solved; each group of auxiliary holes in the rear section 32 of the sizing sleeve is provided with 16-20 auxiliary holes, 12-14 rows, and the inner diameter of the auxiliary holes is small, and they are evenly distributed in the rear half of the upper and lower bodies of the sizing sleeve. Because the pressure cannot be accurately controlled after the vacuum tank is evacuated, this pre-sizing device is not affected by the water pressure in the vacuum tank. Through multiple uniform auxiliary holes, it can ensure that the tube body is evenly hit by water through the tiny auxiliary holes, and the outer surface of the tube body will be smoother and the outer diameter will be more uniform.

[0044] The working principle of the pre-cooling water tank is as follows: The temperature of the thermostatic water tank is maintained at 28-30°C. The temperature in the water tank is detected by a temperature sensor and controlled at 28-30 degrees. If the temperature in the water tank is lower or higher than this temperature, the temperature controller is used to adjust the temperature to reach the appropriate temperature. After passing through the sizing sleeve, the tube body enters the thermostatic water tank 13. The temperature of the thermostatic water tank 13 is stabilized at 28-30°C. The tube body is not completely shaped, so the tube body is pre-cooled; if the inner and outer diameters of the tube body are uneven and the ovality is not good enough, the vacuum water tank 17 is used to evacuate the tube body to adjust the inner and outer diameters of the tube body to be uniform and the ovality.

[0045] Thermostatic water tanks can ensure that all parts of the product shrink at the same rate during the cooling process, thereby accurately controlling the dimensional accuracy of the product. Thermostatic water tanks help optimize the internal structure of the material. For polymer materials, the cooling rate has an important influence on its crystal morphology and internal stress. Constant temperature cooling can make the material form a more uniform crystal structure. For example, when producing polypropylene (PP) plastic products, suitable constant temperature cooling conditions can make PP form more perfect crystals and improve the strength and toughness of the product. During the cooling process, if the water temperature fluctuates greatly, it may cause defects such as ripples and pitting on the surface of the product. Thermostatic water tanks provide a stable cooling environment to ensure that the product can be gradually cooled at a suitable temperature after coming out of the extruder, avoiding surface defects caused by rapid cooling or uneven cooling.

[0046] A method for preparing a hard pipe body forming device comprises the following steps: (1) Dry the material and select the mold and corresponding extrusion parameters according to the material; TPU and PA pellets need to be dried at 80-100°C for 2-6 hours; PVC and PP pellets do not need to be dried.

[0047] For molds, due to the different stretching and compression ratios of PVC, TPU, PP, and PA, the design of the die core rod is also different. The size of the PVC die core rod is 1.0-1.4 times the wall thickness of the tube body; the size of the TPU die core rod is 1.2-1.5 times the wall thickness of the tube body; the size of the PP die core rod is 1.0-1.2 times the wall thickness of the tube body; the size of the PA die core rod is 1.4-3.0 times the wall thickness of the tube body.

[0048] The extrusion parameters are set as follows: Extrusion parameters of TPU extruder: barrel zone 1: 170-175°C; barrel zone 2: 173-178°C; barrel zone 3: 180-185°C; flange: 178-183°C; mold temperature: 178-183°C; screw speed: 8-12r / min; The extrusion parameters of the PVC extruder include: barrel zone 1: 168-172°C; barrel zone 2: 170-175°C; barrel zone 3: 175-180°C; flange: 173-178°C; screw speed: 8-12r / min; The extrusion parameters of the PP extruder include: barrel zone 1: 188-192°C; barrel zone 2: 230-232°C; barrel zone 3: 240-242°C; flange: 220-225°C; screw speed: 8-12r / min; The extrusion parameters of the PA extruder include: barrel zone 1: 170~172℃; barrel zone 2: 180~182℃; barrel zone 3: 190~192℃; flange: 208~212℃; screw speed: 8~12r / min.

[0049] (2) Extrusion Install the die and mandrel that are suitable for the size of the tube body, and calibrate the positions of the die and mandrel. Then add the dried material into the barrel, and extrude the molten material through the die by pressurizing the screw. When extruding the tube embryo, since the tube body is relatively hard, the distance between the sizing sleeve and the die is 35-50mm when the tube embryo is extruded into a soft tube. However, this distance is too large for hard tube extrusion. When extruding hard tubes, the distance between the sizing sleeve and the die is adjusted to between 10-25mm. When the distance is large, since the material is relatively hard, the tube body is easy to be shaped at room temperature, and the vacuum will be affected after entering the constant temperature water tank, affecting the ovality and size uniformity of the tube body.

[0050] (3) Install the sizing part and sizing sleeve Install and fix the upper and lower bodies of the sizing sleeve, and adjust the distance between them and the rear die; The inner cavity size is about 0.2mm larger than the outer diameter of the tube body, but due to different materials, the length of the sizing sleeve is also different: the length of the PP sizing sleeve is 14-22 times the outer diameter of the tube body; the length of the PA sizing sleeve is 12-23 times the outer diameter of the tube body; the length of the TPU sizing sleeve is 14-22 times the outer diameter of the tube body; the length of the PVC sizing sleeve is 15-33 times the outer diameter of the tube body. In other words, when the diameter of the tube embryo is large, the length should be small; otherwise, the length should be large. In addition, the large value is used when extruding a soft tube, and the small value is used when extruding a hard tube.

[0051] (4) Pre-cooling water tank The pipe body enters the constant temperature water tank for pre-cooling, and the temperature of the constant temperature water tank is maintained at 28-30℃, and then enters the vacuum water tank; the vacuum degree of the vacuum water tank is 23Kpa-65Pkpa.

[0052] (5) Cooling and shaping The traction machine pulls the tube embryo into the cooling water tank for shaping. The water temperature in the cooling water tank is 10℃-15℃, which gives the tube body the final shaping.

[0053] (6) Traction ultrasonic closed loop Turn on the traction machine, set the traction speed, close the loop and adjust the traction speed in real time; (7) Cutting and forming Cut into appropriate length according to product usage requirements.

[0054] The following is further described in conjunction with specific embodiments: Example 1 The ovality of the extruded tube is 0.00-0.025, the inner diameter is 0.22±0.05mm, and a 25# extruder is used.

[0055] (1) Extrusion: Install the die and mandrel that are suitable for the size of the tube, and calibrate the position of the die and mandrel. Add the dried material into the barrel, and extrude the molten material through the die by applying pressure with the screw.

[0056] (2) Predetermined diameter: A new sizing device is selected with an inner diameter of 2.4mm, a sizing length of 22mm, a hole diameter of 1.5mm in the front section, and a hole diameter of 0.1mm in the rear section after vacuuming. The distance between the new sizing sleeve and the rear die is adjusted to 25mm, so that the tube body passes through the new sizing sleeve into the constant temperature vacuum water tank.

[0057] (3) Pre-cooling water tank: The tube body is placed in a constant temperature water tank, the water tank temperature is maintained at 28-30°C, the vacuum degree is 65KPa, the tube body is not completely formed, the tube body is pre-cooled, and the tube body is vacuumed.

[0058] (4) Cooling and shaping: Use a 4m cooling water tank to pull the tube embryo into the cooling water tank, set the cooling water temperature to 10℃, and the control accuracy is ±2℃.

[0059] (5) Traction ultrasonic closed loop: Turn on the traction machine and set the traction speed to 18r / min-22r / min; use an ultrasonic thickness gauge and a laser diameter gauge to monitor the inner diameter, outer diameter, wall thickness, and ovality of the tube in real time. When there is a deviation between the actual measured value and the expected set value, the system will send a deviation signal, and use this deviation signal to adjust the traction speed to ensure the stability of tube extrusion.

[0060] (6) Cutting and forming: According to the product usage requirements, it is cut into appropriate lengths to obtain hard tubes. The extrusion process is stable, the wall thickness of the hard tube is uniform and thin, and 30 tubes are randomly selected for inspection. The test results of ovality are 0.001-0.013 and the inner diameter is 0.21-0.23mm, which meets the expected technical requirements.

[0061] Comparative Example The test results of ovality are 0.001-0.013, inner diameter is 0.21-0.23mm, and 25# extruder is used.

[0062] (1) Extrusion: Install the die and mandrel that are suitable for the size of the tube, and calibrate the position of the die and mandrel. Add the dried material into the barrel, and extrude the molten material through the die by applying pressure with the screw.

[0063] (2) Vacuum sizing: The inner diameter is 2.4 mm, the sizing length is 22 mm, the vacuum hole diameter is 1.5 mm, the vacuum degree is 65 KPa, and the distance between the vacuum sizing sleeve and the rear die is adjusted to 25 mm, so that the tube embryo passes through the vacuum sizing sleeve and enters the vacuum box.

[0064] (3) Cooling and shaping: Pull the tube body into the cooling water tank with the cooling water temperature at 10℃.

[0065] (4) Turn on the traction machine and set the traction speed to 18r / min-22r / min. Use an ultrasonic thickness gauge and a laser diameter gauge to monitor the inner diameter, outer diameter, wall thickness, and ovality of the tube in real time. When there is a deviation between the measured value and the expected setting value, the system will send a deviation signal, and use this deviation signal to adjust the traction speed to ensure the stability of the tube extrusion.

[0066] (5) Cutting and forming: Cut into appropriate lengths according to product use requirements to obtain hard tubes. The hard tubes have thick walls and unstable dimensions. 30 tubes were randomly sampled and the test results showed that the ovality was 0.045-0.088 and the inner diameter was 0.20-0.25mm, which did not meet the expected technical requirements.

[0067] The comparison results are as follows: The inner and outer diameters of the tube extruded by using a pre-sizing device and a pre-cooling water tank are consistent and uniform, the extrusion process is stable, the tested tube ovality is 0.001-0.013, and the inner diameter is 0.21-0.23mm, which meets the expected technical requirements.

[0068] The pre-forming device was not used and the extrusion process was unstable. The test results of ovality were 0.045-0.088 and inner diameter were 0.20-0.25mm, which did not meet the expected technical requirements.

[0069] Comparing the test results, using the pre-forming device, the wall of the extruded tube is thin and uniform, the extrusion process is stable, and real-time correction can be made to improve the pass rate, thereby reducing costs and achieving precision extrusion. The extrusion ovality can be within 0.015 and the extrusion accuracy can reach 0.01.

[0070] The present invention discloses a hard tube forming device and a preparation method thereof, which adopts a split sizing device. The sizing device adopts a split design of front and rear parts. The front part has a common sizing effect, and the rear part has a plurality of small holes. The split sizing sleeve with a plurality of small holes improves the rough surface of the tube body and the uneven outer diameter of the tube body; it also improves the traction trouble during extrusion and the problem of material blockage by the sizing sleeve, and saves the problem of material waste during extrusion. By this method, the product quality of the hard tube body can be improved, the product qualification rate can be increased, and the cost can be reduced. The extrusion ovality can reach within 0.015.

[0071] As for the constant temperature pre-cooling water tank, the ordinary extrusion production line has only one cooling water tank. The catheter enters the cooling water tank directly after being pulled, which will lead to inconsistent cooling speed, resulting in quality problems such as pipe bending or dimensional deviation. The present invention adds a pre-cooling water tank before the ordinary cooling water tank. Through the cooperation of the constant temperature water tank and the vacuum water tank, it is ensured that all parts of the product shrink at the same rate during the cooling process, thereby accurately controlling the dimensional accuracy of the product and solving the problems of uneven inner and outer diameters and ovality. The constant temperature water tank can reduce the surface defects of the hard catheter, improve product quality, reduce the waste of raw materials, control product quality, reduce the scrap rate, thereby improving production efficiency and reducing production costs.

[0072] The cooling and shaping of the tube body is divided into two water tanks. The ordinary extrusion production line has only one water tank with a temperature of about 10°C. When the hard tube directly enters the water tank with a lower temperature from the extruder, it is immediately shaped, which will cause related quality problems such as large tube ovality. If the water tank temperature is set to about 28°C, although the sizing effect can be achieved, the tube body is not completely cooled, which will cause the problem of tube body bending or deformation during later storage. In the present invention, the first pre-cooling water tank, that is, the temperature of the constant temperature water tank is controlled at 28-30°C. After the tube body is extruded and formed, it is first pre-shaped in the constant temperature water tank, and the vacuum water tank is evacuated. The ovality of the tube body is stable, and then it enters the cooling water tank with a temperature of about 10°C to thoroughly cool the formed tube body. In this way, the later storage of the tube body reduces the deformation and bending of the tube body, thereby improving the qualified rate of later processing, reducing the scrap rate in later processing, and saving production costs.

[0073] If the words "first", "second" and the like are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and the above words have no special meaning.

[0074] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the invention claimed for protection. The scope of protection claimed for the present invention is defined by the attached claims and their equivalents.

[0075] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0076] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc. indicate directions or positional relationships based on the directions 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 device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. A hard tube body forming device, comprising an extruder part, a predetermined diameter part, a cooling part, a traction ultrasonic closed loop and a cutting part, wherein the extruder part comprises an extruder and a die head and an extrusion die mounted on the extruder, characterized in that: The predetermined sizing part comprises a sizing sleeve upper body and a sizing sleeve lower body which are separated and assembled, and a sizing sleeve front fixing plate and a sizing sleeve rear fixing plate which are sleeved on the two bodies at intervals, and the sizing sleeve front fixing plate and the sizing sleeve rear fixing plate divide it into a sizing sleeve front section and a sizing sleeve rear section, and the sizing sleeve front fixing plate is sleeved on the head end of the sizing sleeve front section and fastens the upper and lower bodies by fixing bolts arranged in the radial direction; The front section of the sizing sleeve is provided with a group of sparsely arranged sizing holes along the axial direction, and each group of sizing holes is provided with a plurality of sizing holes along the circumferential direction. The rear section of the sizing sleeve is provided with a group of auxiliary holes densely arranged along the axial direction, and each group of auxiliary holes is provided with a plurality of auxiliary holes along the circumferential direction, and the diameter of the auxiliary holes is much smaller than the diameter of the sizing holes; The cooling part includes a pre-cooling water tank and a cooling water tank, and the pre-cooling water tank includes a constant temperature water tank and a vacuum water tank, the water temperature of the vacuum water tank is consistent with the water temperature of the constant temperature water tank, the front section of the sizing sleeve is located in the constant temperature water tank, and the rear section of the sizing sleeve is located in the vacuum water tank; The tube extruded through the sizing sleeve is pre-cooled in a constant temperature water tank and then enters a vacuum water tank. It is then shaped in a cooling water tank under the traction of a traction machine placed at the rear end of the vacuum water tank. It is then extruded through a traction ultrasonic closed loop and cut into the required length by the cutting section.

2. A hard tube forming device according to claim 1, characterized in that: The front fixing plate of the sizing sleeve is fixed on the water baffle plate arranged at the front end of the constant temperature water tank, and the rear fixing plate of the sizing sleeve is arranged between the two side walls of the constant temperature water tank and the vacuum water tank.

3. A hard tube forming device according to claim 1, characterized in that: The vacuum water tank is fixed on a provided water tank rack, and the constant temperature water tank is fixed on the vacuum water tank and the temperature is controlled by a provided constant temperature sensor and a temperature controller.

4. A hard tube forming device according to claim 1, characterized in that: The sizing hole groups are provided with 1 to 6 groups, and the sizing hole diameters are 1 to 3 mm; The auxiliary hole groups are provided with 10 to 30 groups, and the auxiliary hole diameters are 0.05 to 0.2 mm.

5. A method for preparing a hard pipe body forming device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Dry the material and select the mold and corresponding extrusion parameters according to the material; (2) Extrusion Install the die and mandrel that are suitable for the size of the tube body, and calibrate the position of the die and mandrel. Then add the dried material into the barrel, and extrude the molten material through the die by pressurizing the screw. (3) Install the sizing part and sizing sleeve Install and fix the upper and lower bodies of the sizing sleeve, and adjust the distance between them and the rear die; (4) Pre-cooling water tank The tube body enters the constant temperature water tank for pre-cooling, and the temperature of the constant temperature water tank is maintained at 28-30℃, and then enters the vacuum water tank; (5) Cooling and shaping The traction machine pulls the tube embryo into the cooling water tank for shaping; (6) Traction ultrasonic closed loop Turn on the traction machine, set the traction speed, close the loop and adjust the traction speed in real time; (7) Cutting and forming Cut into appropriate length according to product usage requirements.

6. The method for preparing a hard tube forming device according to claim 5, characterized in that: In step (1), if the material is TPU or PA pellets, it is dried at 80-100°C for 2-6 hours; If the material is PVC or PP granules, drying is not required.

7. The method for preparing a hard tube forming device according to claim 5, characterized in that: In step (1), if PVC pellets are used as the material, the size of the die core rod of the mold needs to be 1.0-1.4 times the wall thickness of the tube body; If TPU pellets are used as the material, the size of the die core rod of the mold must be 1.2-1.5 times the wall thickness of the tube; If PP granules are used as the material, the size of the die core rod of the mold must be 1.0-1.2 times the wall thickness of the tube; If PA granules are used as the material, the size of the die core rod of the mold must be 1.4-3.0 times the wall thickness of the tube.

8. The method for preparing a hard tube forming device according to claim 5, characterized in that: In step (3), if PVC pellets are used as the material, the length of the sizing sleeve must be 15-33 times the outer diameter of the tube; If TPU pellets are used as the material, the length of the sizing sleeve must be 14-22 times the outer diameter of the tube; If PP granules are used as the material, the length of the sizing sleeve must be 14-22 times the outer diameter of the tube; If PA granules are used as the material, the length of the sizing sleeve must be 12-23 times the outer diameter of the tube.

9. The method for preparing a hard tube forming device according to claim 5, characterized in that: The temperature of the constant temperature water tank is 28-30°C, and the water temperature in the cooling water tank is 10°C-15°C.

10. The method for preparing a hard tube forming device according to claim 5, characterized in that: The vacuum degree of the vacuum water tank is 23Kpa-65Pkpa, and the top cover of the vacuum water tank is provided with a glass baffle for sealing.

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