Tool clamp for balloon forming and non-compliance balloon forming method

Abstract

The invention relates to a work fixture for balloon forming and a non-compliance balloon forming method.The work fixture comprises a sealing piece, a hollow connecting piece and a pair of clamping pieces; a channel used for containing a balloon tube is formed in the clamping piece, and the channel is in clearance fit with the balloon tube. The inner walls of the two clamping pieces are each provided with a conical face, and the two conical faces are axially arranged and can move in the opposite directions. The hollow connecting piece is used for introducing working gas into the balloon tube, and the outer diameter of the hollow connecting piece is in clearance fit with the inner diameter of the balloon tube; the sealing piece is matched with a space limited by the two conical surfaces; when the two conical surfaces move oppositely, the sealing piece is extruded to generate axial force, and the axial force is decomposed into radial pressing force through matching with the conical surfaces, so that the balloon pipe is in close contact with the hollow connecting piece.

Description

Technical Field

[0001] The present invention relates to the technical field of the production and manufacturing of interventional medical devices, and particularly relates to a tooling fixture for balloon forming and a non-compliant balloon forming method. Background Art

[0002] The balloon catheter is an important medical device in interventional therapy. Among them, the non-compliant balloon is widely used in surgeries such as angioplasty and stent release due to its characteristics of small diameter change and strong supporting force during the expansion process. The performance of the non-compliant balloon directly affects the surgical effect and patient safety, and the uniformity, strength, and dimensional accuracy of the balloon are key indicators.

[0003] The traditional balloon forming process usually adopts a single heating and simple stretching method, which is difficult to precisely control the uniformity of the balloon wall thickness. During the forming process, due to the uneven distribution of material stress, defects such as local thinning or wrinkling of the balloon often occur. Especially in the stage where the balloon fits with the mold, after one end adheres to the wall, it is easy to cause uneven stress, thereby affecting the product quality.

[0004] In addition, in the prior art, the clamping mechanism of the balloon forming device is relatively simple, and it is difficult to maintain stable sealing and clamping force during the high-pressure forming process, which may lead to problems such as air leakage and balloon detachment during the stretching process, not only affecting the product quality but also resulting in a high rejection rate. At the same time, the traditional process has relatively rough control over parameters such as temperature, pressure, and stretching speed, and it is difficult to meet the preparation requirements of different specifications of balloons.

[0005] Furthermore, the existing balloon forming processes generally have the problem of a narrow process window. Limited by the limitations of equipment and processes, it is difficult for operators to make flexible adjustments according to different material characteristics and product specifications, which makes the qualified rate of balloon products generally low, increasing the production cost. Especially when preparing large-sized or special-sized balloons, due to the difficulty in optimizing process parameters, the yield is often even lower.

[0006] Therefore, there is an urgent need to develop a new forming process with high process fault tolerance and capable of ensuring the consistency and stability of balloon products to improve the qualified rate of balloon products and meet the quality requirements of clinical applications. Summary of the Invention

[0007] The present invention discloses a tooling fixture for balloon forming and a non-compliant balloon forming method, aiming to solve the technical problems existing in the prior art.

[0008] The present invention adopts the following technical solutions:

[0009] On the one hand, an embodiment of the present invention provides a tooling fixture for balloon forming, including a seal, a hollow connecting piece, and a pair of clamping pieces;

[0010] The clamping member is provided with a channel for accommodating the balloon tube, and the channel is in clearance fit with the balloon tube; a tapered surface is provided on the inner wall of each of the two clamping members, and the two tapered surfaces are axially arranged and can move towards each other.

[0011] The hollow connector is used to introduce working gas into the balloon tube, and its outer diameter is in clearance fit with the inner diameter of the balloon tube.

[0012] The seal is fitted to the space defined by the two tapered surfaces; when the two tapered surfaces move towards each other, the seal is squeezed to generate an axial force, and the axial force is decomposed into a radial pressing force through the cooperation with the tapered surfaces, so that the balloon tube is in close contact with the hollow connector.

[0013] As a preferred technical solution, the seal includes a plurality of sealing rings arranged axially in sequence, the outer diameter of the sealing ring is smaller than the maximum inner diameter of the inner wall of the clamping member, and the inner diameter of the sealing ring is close to the outer diameter of the balloon tube.

[0014] As a preferred technical solution, the total cross-sectional area of the plurality of sealing rings is larger than the maximum cross-sectional area defined by the two tapered surfaces and the outer surface of the balloon tube.

[0015] As a preferred technical solution, a pair of clamping members are configured as a first clamping portion and a second clamping portion, which are nested and can move axially.

[0016] The two tapered surfaces are respectively provided at one end of the first clamping portion away from the second clamping portion and at one end of the second clamping portion close to the first clamping portion.

[0017] As a preferred technical solution, the angle between the tapered surface and the axial direction is 30° to 45°.

[0018] On the other hand, the embodiment of the present invention also provides a method for forming a non-compliant balloon, including the following steps:

[0019] Fix one end of the balloon tube with a first chuck and fix the other end of the balloon tube with a second chuck, and the area of the balloon tube to be formed is placed in a forming mold; wherein the first chuck is configured as the tooling fixture described in any one of the above.

[0020] Perform a first heating on the balloon tube, and introduce a low-pressure working gas through the first chuck, and maintain it for a predetermined time at a preset temperature.

[0021] Introduce working gas into the balloon tube, and during the process of gradually increasing the pressure, perform a first stretching on the balloon tube until the ultimate stress of the balloon tube is reached.

[0022] While maintaining the working gas pressure, perform a second heating and a second stretching on the balloon to make the balloon fully formed.

[0023] The formed balloon is heated for the third time and heat-set at a high temperature to remove internal stress;

[0024] After the balloon is cooled to a predetermined temperature, it is demolded step by step.

[0025] As a preferred technical solution, one end of the balloon tube is fixed by a first chuck, and the other end of the balloon tube is fixed by a second chuck. In the step of placing the area to be formed of the balloon tube in the forming die, it includes:

[0026] Insert the left end of the balloon tube into the first chuck;

[0027] Drive the conical surfaces of the first clamping part and the second clamping part in the first chuck to move towards each other respectively, so that the seal is extruded to generate a radial pressing force, and the balloon tube is hermetically fixed to the hollow connecting piece;

[0028] Place the area to be formed of the balloon tube in the forming die,

[0029] At the same time, introduce gas into the heating jacket of the forming die to keep the heating jacket in a dry state.

[0030] As a preferred technical solution, in the step of heating the balloon tube for the first time and introducing low-pressure working gas through the first chuck and maintaining it for a predetermined time at a preset temperature, it includes:

[0031] Control the temperature of the heating jacket of the forming die to rise to the preset temperature;

[0032] While heating, introduce low-pressure working gas into the balloon tube through the first chuck;

[0033] Use the heating jacket to uniformly heat the area to be formed of the balloon tube;

[0034] Maintain for a predetermined time at the preset temperature to make the balloon tube reach a softened state.

[0035] As a preferred technical solution, the preset temperature is 90 - 130 °C, the working gas is nitrogen, and the pressure of the working gas is lower than the pressure for balloon forming.

[0036] As a preferred technical solution, in the step of using the heating jacket to uniformly heat the area to be formed of the balloon tube, it further includes:

[0037] Pre-stretch the balloon tube to reduce the wall thickness of the balloon.

[0038] As a preferred technical solution, in the step of introducing working gas into the balloon tube and performing the first stretch on the balloon tube during the process of gradually increasing the pressure until the ultimate stress of the balloon tube is reached, it includes:

[0039] Introduce working gas with a pressure lower than the forming pressure into the balloon tube;

[0040] Control the pressure of the working gas to rise to the forming pressure at a preset slope;

[0041] During the process of the working gas pressure rising, drive the first chuck and the second chuck to move synchronously in opposite directions to axially stretch the balloon tube. The axial stretching speed matches the rising speed of the working gas pressure until the moving stops when the area to be formed of the balloon tube reaches the ultimate stress.

[0042] As a preferred technical solution, after the steps of introducing working gas into the balloon tube and performing the first stretching on the balloon tube during the process of the pressure gradually rising until reaching the ultimate stress of the balloon tube, it further includes:

[0043] Maintain the working gas pressure and control the first chuck and the second chuck to respectively maintain a preset tensile force value;

[0044] Maintain the preset tensile force value within a preset time to adjust the grip depth of the balloon tube and fully expand the area to be formed.

[0045] As a preferred technical solution, in the step of performing the second heating and secondary stretching on the balloon to completely form the balloon while maintaining the working gas pressure, it includes:

[0046] When the balloon tube reaches the maximum stress state, control the temperature of the heating jacket of the forming die to rise;

[0047] Make the first chuck and the second chuck respectively maintain a preset tensile force value;

[0048] During the process of the temperature rising, respectively control the movement of the first chuck and the second chuck to adjust the grip depth of the balloon and reduce the wall thickness of the conical end of the balloon;

[0049] Maintain the working gas pressure until the area to be formed of the balloon tube completely adheres to the inner wall of the forming die.

[0050] As a preferred technical solution, in the step of performing the third heating and high-temperature setting on the formed balloon to remove internal stress, it includes:

[0051] Raise the temperature of the heating jacket of the forming die to a preset temperature higher than the second heating temperature;

[0052] Reduce the working gas pressure to a preset pressure lower than the forming pressure;

[0053] Maintain the temperature and pressure to perform setting treatment on the balloon until there is no stress whitening phenomenon on the balloon;

[0054] Turn off the heating jacket of the forming die.

[0055] As a preferred technical solution, in the step of demolding in steps after the balloon is cooled to a predetermined temperature, it includes:

[0056] Under the condition of maintaining the working gas pressure, introduce a cooling medium into the heating jacket of the forming die;

[0057] After the balloon is cooled to the preset temperature, maintain the working gas pressure, open the first chuck on the left side, and make the balloon tube semi-disengage from the seal, while keeping the connection between the balloon tube and the hollow connector to maintain the working gas pressure;

[0058] Open the second chuck on the right side;

[0059] Drive the first chuck and the second chuck to move away from the forming die in sequence, and the moving speed of the second chuck is greater than that of the first chuck;

[0060] Open the forming die, release the working gas pressure, and take out the formed balloon.

[0061] As a preferred technical solution, in the step of opening the first chuck on the left side, it includes:

[0062] Drive the first chuck to move leftward at a preset speed to disengage the balloon tube from the seal;

[0063] Keep the connection between the balloon tube and the hollow connector to maintain the working gas pressure.

[0064] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0065] The present invention mainly provides a tooling fixture for balloon forming and a method for forming a non-compliant balloon. Among them, the tooling fixture realizes the reliable sealing between the balloon tube and the hollow connector through the structural design of setting a seal, a hollow connector and a pair of clamping members, and using a conical surface to convert the axial force into a radial pressing force. This structure not only avoids the problem of seal failure of traditional fixtures in high-temperature and high-pressure environments, but also ensures the stable and controllable pressure of the working gas, thus providing a guarantee for the precise forming of the balloon; at the same time, the tooling fixture is convenient to load and unload, has strong reusability, and can significantly improve the working efficiency of balloon forming.

[0066] Furthermore, the non-compliant balloon forming method of the present invention adopts a process combining three times of heating and segmented stretching. By precisely controlling the working gas pressure, stretching speed, and heating temperature, the balloon is uniformly stressed during the forming process, effectively avoiding quality problems such as uneven wall thickness and inconsistent strength of the balloon. Especially during the first stretching process, through the matching control of the working gas pressure and stretching speed, and the adjustment of the grip pattern depth of the balloon during the second stretching process, the dimensional accuracy and service performance of the balloon are ensured. In addition, a step-by-step demolding process is adopted. By maintaining the connection between the balloon tube and the hollow connector to maintain the working gas pressure, the deformation of the balloon during the demolding process is effectively prevented, and finally a non-compliant balloon with better appearance quality and performance is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments, which form a part of the present invention. The schematic embodiments of the present invention and their explanations explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0068] Figure 1 It is a schematic structural diagram of a tooling fixture disclosed in a preferred embodiment of Embodiment 1 of the present invention;

[0069] Figure 2 It is a schematic structural diagram of a balloon tube disclosed in a preferred embodiment of Embodiment 1 of the present invention;

[0070] Figure 3 It is an assembly schematic diagram of a balloon tube, a first chuck, and a forming die disclosed in a preferred embodiment of Embodiment 2 of the present invention;

[0071] Figure 4 It is an assembly schematic diagram of a balloon tube, a first chuck, a second chuck, and a forming die disclosed in a preferred embodiment of Embodiment 2 of the present invention;

[0072] Figure 5 It is a schematic diagram of the balloon forming process for the area to be formed disclosed in a preferred embodiment of Embodiment 2 of the present invention;

[0073] Figure 6 It is a schematic diagram of the demolding process disclosed in a preferred embodiment of Embodiment 2 of the present invention.

[0074] Description of the reference numerals:

[0075] Balloon tube 10, area to be formed 11, hollow connector 21, first clamping portion 22, second clamping portion 23, tapered surface 231, sealing ring 24, first chuck 31, second chuck 32, forming die 33. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0076] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is generally used in the sense of including "and / or", unless otherwise explicitly specified in the content.

[0077] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" 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 directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

[0078] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the limiting conditions under which the present invention can be implemented. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the objectives that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear narration, and are not used to limit the scope that the present invention can be implemented. In the description of this application, the terms "first", "second", etc. are only used for differential description and cannot be understood as indicating or implying relative importance.

[0079] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0080] Example 1

[0081] The existing clamping mechanism has a simple design and is difficult to maintain stable sealing performance and clamping force during the high-pressure forming process, and problems such as air leakage and balloon detachment are likely to occur. To solve the problems existing in the prior art, this embodiment provides a tooling fixture for balloon forming, which can clamp the end of the balloon tube during balloon forming and can achieve a more reliable sealing effect.

[0082] Such as Figure 1 and Figure 2, in some embodiments, the tooling fixture includes a seal, a hollow connecting member 21, and a pair of clamping members. Among them, the two clamping members are respectively configured as a first clamping portion 22 and a second clamping portion 23. The two are nested and can move axially. A channel for accommodating the balloon tube 10 is provided inside them. The channel is in clearance fit with the balloon tube 10 and is coaxially arranged with the balloon tube 10 to ensure the coaxiality of the balloon tube 10 during the clamping process; the hollow connecting member 21 can pass through the balloon tube 10 and introduce working gas into the balloon tube 10. Its outer diameter is in clearance fit with the inner diameter of the balloon tube 10; the seal is arranged between the first clamping portion 22 and the second clamping portion 23 and can radially press the balloon tube 10 tightly.

[0083] In some embodiments, a tapered surface 231 is provided on the inner walls of both the first clamping portion 22 and the second clamping portion 23. The two tapered surfaces 231 are respectively arranged at one end of the first clamping portion 22 far from the second clamping portion 23 and one end of the second clamping portion 23 close to the first clamping portion 22. The two tapered surfaces 231 can move towards each other; the seal cooperates with the space restricted by the two tapered surfaces 231. When the two tapered surfaces 231 move towards each other, the seal is squeezed to generate an axial force, and the axial force is decomposed into a radial pressing force through the cooperation with the tapered surface 231, so that the balloon tube 10 is in close contact with the hollow connecting member 21.

[0084] In some embodiments, the first clamping portion 22 includes a cylindrical body extending axially. One end is provided with a connecting surface for cooperating with the second clamping portion 23, and the other end is provided with the tapered surface 231; the second clamping portion 23 also includes a cylindrical body. One end is also provided with the tapered surface 231, and the other end is provided with a connecting surface for cooperating with the first clamping portion 22. The connecting surface of the first clamping portion 22 and the connecting surface of the second clamping portion 23 can cooperate with each other to realize the relative axial movement of the two clamping members.

[0085] In some embodiments, the seal includes a plurality of sealing rings 24 arranged axially in sequence. The outer diameter of the sealing ring 24 is smaller than the maximum inner diameter of the inner wall of the clamping member, and the inner diameter of the sealing ring 24 is close to the outer diameter of the balloon tube 10. It should be noted that the "close" here means that the balloon tube 10 can be slightly larger than the inner diameter of the sealing ring 24 or slightly smaller than the inner diameter of the sealing ring 24, mainly based on the specifications of the balloon tube 10 that are easily obtained in actual production. In some embodiments, the unilateral clearance during the clearance fit between the two is less than 0.2 mm, and the unilateral interference during the interference fit is less than 0.2 mm. The total cross-sectional area of the plurality of sealing rings 24 is larger than the maximum cross-sectional area defined by the two tapered surfaces 231 and the outer surface of the balloon tube 10, so that the sealing ring 24 can be fully deformed when being squeezed by the two tapered surfaces 231, thereby providing sufficient sealing pressure.

[0086] In some embodiments, the angle between the two conical surfaces 231 and the axial direction is 30° to 45°. This angle can ensure that the sealing ring 24 receives sufficient radial pressing force and will not cause excessive deformation of the sealing ring 24 due to too small an angle. When the first clamping portion 22 and the second clamping portion 23 move axially towards each other, the conical surface 231 can evenly decompose the axial force F on the sealing ring 24 into a radial pressing force, so that the sealing ring 24 evenly presses the balloon tube 10.

[0087] Specifically, according to the principle of force decomposition, the forces exerted by the two conical surfaces 231 on the sealing ring 24 can be decomposed into a radial force and an axial force along the circumferential direction. Among them, the radial force causes the sealing ring 24 to exert a pressing effect on the balloon tube 10, while the axial force is restricted by the axial frictional resistance; therefore, the smaller the angle between the conical surface 231 and the axial direction, the greater the axial frictional resistance, and at this time the balloon tube 10 can withstand a greater tensile force without coming off.

[0088] In some embodiments, the outer diameter of the hollow connector 21 is 0.1 - 0.2 mm smaller than the inner diameter of the balloon tube 10. This clearance fit can not only ensure the smooth insertion of the hollow connector 21 into the balloon tube 10, but also achieve reliable sealing under the action of the radial pressing force of the sealing ring 24; similarly, the inner diameter of the inner channel of the clamping member is 0.1 - 0.2 mm larger than the outer diameter of the balloon tube 10, which is convenient for the loading and unloading of the balloon tube 10 and can ensure the accurate positioning of the balloon tube 10 during the sealing process.

[0089] In some embodiments, the outer diameter of the sealing ring 24 is smaller than the maximum outer diameter of the first clamping portion 22 and the second clamping portion 23, and the unilateral clearance is 0.1 - 0.2 mm, so as to facilitate the smooth relative sliding of the first clamping portion 22 and the second clamping portion 23, and at the same time provide a certain radial deformation space for the sealing ring 24; the inner diameter of the sealing ring 24 is smaller than the outer diameter of the balloon tube 10, so that the sealing ring 24 has a certain sense of breakthrough during the assembly process, which is convenient for the operator to perceive the state of completion of loading.

[0090] In some embodiments, the above-mentioned tooling fixture is clamped at the left end of the balloon tube 10, and the right side thereof is the to-be-formed area 11 of the balloon tube 10. The to-be-formed area 11 is about 1 / 3 to 1 / 2 of the length of the balloon finished product. Another chuck is also provided at the right end of the to-be-formed area 11, and the chuck at the right end can be configured as an ordinary clip-type structure. The above-mentioned working fixture and chuck respectively stretch the balloon tube 10 to the left and right sides, and the workpiece obtained after heating, stretching and cooling the to-be-formed area 11 therebetween is the balloon bubble tube, and the left end of the balloon bubble tube needs to be intercepted after determining the length.

[0091] Example 2

[0092] Traditional balloon forming processes mostly use single-step heating and simple stretching methods, making it difficult to precisely control the wall thickness uniformity of the balloon. As a result, the balloon is prone to local thinning or wrinkling. Especially during the stage where the balloon adheres to the mold, uneven stress is likely to occur after single-end wall adhesion. To solve this problem, in this Example 2, a non-compliant balloon forming method is provided. The balloon tube 10 can be made of nylon, Pebax, or a double-extruded tube of nylon and Pebax. The method includes the following steps:

[0093] Step S410: Fix one end of the balloon tube with a first chuck and the other end with a second chuck, and place the area to be formed of the balloon tube inside the forming mold.

[0094] Reference Figure 3 、 Figure 4 In some embodiments, the first chuck 31 is the tooling fixture described in the above Example 1, and the second chuck 32 can be configured as a common clip-type structure.

[0095] In some embodiments, insert the left end of the balloon tube 10 into the first chuck 31, and respectively drive the conical surfaces 231 of the first clamping portion 22 and the second clamping portion 23 in the first chuck 31 to move towards each other, so that the seal is squeezed to generate a radial pressing force, and the balloon tube 10 is sealed and fixed to the hollow connecting member 21. Then insert the right end of the balloon tube 10 into the second chuck 32, and place the area 11 to be formed of the balloon tube 10 inside the forming mold 33.

[0096] In some embodiments, to prevent the heating jacket from retaining cooling water due to a previous special cause, resulting in the forming mold 33 being unable to rise to the specified temperature, therefore, while inserting the balloon tube 10 into the forming mold 33, introduce gas into the heating jacket of the forming mold 33 to keep the heating jacket in a dry state.

[0097] Step S420: Perform the first heating on the balloon tube, and introduce low-pressure working gas through the first chuck, and maintain it at a preset temperature for a predetermined time.

[0098] In some embodiments, control the temperature of the heating jacket of the forming mold 33 to rise to the preset temperature. At the same time, introduce low-pressure working gas from the first chuck 31 into the balloon tube 10, and use the heating jacket to uniformly heat the area 11 to be formed of the balloon tube 10, and maintain it at the preset temperature for a predetermined time to make the balloon tube 10 reach a softened state.

[0099] In some embodiments, the preset temperature for the first heating is 90 - 130 °C, and the working gas is preferably nitrogen, and its pressure is much lower than the pressure for balloon forming, preferably 5 bar.

[0100] In some embodiments, when heating the to-be-formed area 11, the balloon tube 10 can be stretched a certain distance first, and at this time, the force value sensor shows an increase in the force value; during the heat preservation process, the force value will decrease, and in cooperation with subsequent steps, the balloon wall thickness can be reduced within a large range; in this embodiment, the specific value of the pulling force during the stretching process is not specifically limited, and those skilled in the art can adjust it as needed, or a preset value of the pulling force can be set, and the stretching is completed when the pulling force drops to a certain preset value. It should be noted that the forming pressure during this heating is inversely proportional to the heating time, but its change range is relatively limited; when it is necessary to reduce the balloon wall thickness, a pre-stretching scheme can be adopted, and if it is not necessary to reduce the wall thickness, the pre-stretching step can be omitted.

[0101] In some embodiments, when heating the to-be-formed area 11, it further includes a heat preservation step. By setting the heat preservation duration and temperature, the internal stress in the to-be-formed area 11 can be reduced. If it is necessary to reduce a large amount of internal stress, it can be stretched a certain distance first and then heat-preserved. At this time, the purpose of reducing the balloon wall thickness can be achieved, ensuring a qualification rate of more than 70%, and the wall thickness can also be reduced by about 12%.

[0102] In some embodiments, the preferred process parameters for the first heat preservation are as follows: at 128 °C and a nitrogen pressure of 5 bar, the first chuck 31 on the left moves to a position 1 mm to the left at a speed of 0.2 mm / s, and the second chuck 32 on the right moves to a position 2 mm to the right at a speed of 0.2 mm / s. When the heat preservation time reaches 100 s, the next step is entered.

[0103] Step S430, introduce working gas into the balloon tube, and during the process of gradually increasing the pressure, perform the first stretching on the balloon tube until the ultimate stress of the balloon tube is reached.

[0104] In some embodiments, introduce working gas with a pressure lower than the forming pressure into the balloon tube 10, control the pressure of the working gas to rise to the forming pressure at a preset slope; during the process of increasing the pressure of the working gas, drive the first chuck 31 and the second chuck 32 to move synchronously in opposite directions to axially stretch the balloon tube 10. During the stretching process, the pressure of the working gas continuously increases to the balloon forming pressure, and the stretching speed matches the rising rate of the working gas pressure until the movement stops when the to-be-formed area 11 of the balloon tube 10 reaches the ultimate stress.

[0105] During the above process, the balloon in the area to be formed 11 is not fully inflated. This is because the volume of the balloon body suddenly increases and the pressure decreases, and the expansion of the balloon body will offset part of the pulling force. When the balloon is not in contact with the wall, the force is evenly distributed during left and right movement, and it will not accidentally stop out of control because the pulling force value exceeds the set value after one end of the balloon contacts the wall and cannot move. In addition, the pressure of the working gas should be set slightly higher than the actual required forming pressure, which can provide a greater operating space for controlling the balloon inflation timing. The choice of the balloon inflation timing is crucial for the formation of the grip pattern: if the balloon is inflated too early, there will be no grip pattern at both ends; if it is inflated too late, the balloon may burst. Within the appropriate range of balloon inflation timing, the balloon inflation timing can be fine-tuned by adjusting the pressure slope, so as to achieve precise control of the balloon wall thickness.

[0106] In some embodiments, the above forming process requires a high-speed camera to capture the display panel of the device and slow down for observation and confirmation. If the grip pattern of the balloon needs to be obvious, more force values need to be reduced during forming. The balloon inflation speed can be increased, the nitrogen flow rate can be increased, or the set speed can be reduced. Conversely, if the grip pattern needs to be less obvious, the reverse operation can be performed.

[0107] It should be noted that the grip pattern of the balloon refers to several fine stripes extending axially on the conical end surfaces at both ends of the balloon in the area to be formed 11 during the forming process due to the stretching effect. These grip patterns are not only the characteristics of the forming process, but also an important guarantee for the safety of the balloon. When the balloon bursts during clinical use, the rupture will preferentially extend along the direction of the grip pattern. This preset rupture path can effectively intercept the circumferential cracks generated by the torsion of the balloon. Therefore, even in the case of balloon rupture, the presence of the grip pattern can ensure that the balloon remains in a relatively complete fragmented state, avoid the generation of free fragments entering the human lumen, and at the same time facilitate the withdrawal of the burst balloon from the body, thus minimizing the safety risk to the patient.

[0108] Such as Figure 5, in some embodiments, step S430 includes the first-stage balloon forming, and its optional process parameters are as follows: the nitrogen pressure is set to 16 bar, which is 0.5 - 1 bar higher than the actual forming pressure; the distances that the first chuck 31 and the second chuck 32 move to the left and right are set to 80 mm, and the left and right pulling force values are set to 450 N. Specifically, the pulling force value of 450 N is set to be much greater than the ultimate stress of 280 N of the actual balloon tube. This set value is used to protect the sensor from over-range and prevent the influence of a smaller force value setting on the speed control during the stretching process; the moving distance of 80 mm at both ends is a position that the first chuck 31 and the second chuck 32 cannot reach. Such a setting can prevent the equipment from being damaged due to the accidental breakage and excessive movement of the balloon tube 10 beyond the stroke during the process. In the actual process, the balloon tube 10 is stretched at a speed of 25 mm / s at both ends until the force value at either end reaches the ultimate stress of 280 N of the balloon tube 10 and then stops. During this process, the stretching speed at both ends remains unchanged until the maximum stress is reached and then stops. The nitrogen pressure gradually reaches the set pressure of 16 bar from 13 bar in 1.1 s. The nitrogen flow rate is the difference between the end pressure of the previous step and the set pressure of this step divided by the slope time. The slope time can control the timing of balloon formation. If a slight increase in the balloon wall thickness is required, the slope time needs to be set smaller, and vice versa. When the balloon appearance is consistent (grip pattern state, straight section length) and the stretching amounts at both ends are close, the wall thickness adjustment range is close to plus or minus 4.3%.

[0109] In some embodiments, step S430 further includes the second-stage balloon forming. In this stage, the first chuck 31 and the second chuck 32 maintain an appropriate pulling force and hold for several seconds under the PLC logic control movement. The closer the moving force value is to the set value, the slower the movement is, so that the pressure reaches the forming pressure and the area to be formed 11 is fully expanded to form a balloon. Align the grip depths at both ends of the balloon with the straight section, and reduce the excess stress at either end or generate a small displacement to increase the stress.

[0110] In some embodiments, the first chuck 31, the second chuck 32, the forming die 33, and the heating sleeve are all controlled by the PLC logic control system. This system uses a programmable logic controller (PLC) and can achieve closed-loop control of the balloon blowing process. Through proportional-integral-derivative (PID) control technology, the system can monitor and feedback the equipment operation parameters in real time, so as to perform automatic adjustment. Specifically, PID control includes three adjustment items: the proportional term is used to directly adjust the response speed of the system, the integral term is used to eliminate the steady-state error of the system, and the derivative term is used to reduce the overshoot and improve the system stability. This intelligent control method ensures the accuracy and stability of various process parameters during the balloon forming process and effectively improves the consistency of the quality of the finally produced balloons.

[0111] In some embodiments, the first-stage balloon forming and the second-stage balloon forming are combined into one balloon forming stage, and the parameters of the two stages can be adjusted according to actual needs to manufacture balloons of multiple specifications with similar outer diameters but different lengths.

[0112] In some embodiments, the optional process parameters for the second-stage balloon forming are as follows: at a temperature of 128°C, the nitrogen pressure rises to 16 bar at 0.7 s, the first chuck 31 on the left is maintained with a force of 270 N, the second chuck 32 on the right is maintained with a force of 260 N, and after a duration of 2 s, it automatically enters the next step.

[0113] Step S440, while maintaining the working gas pressure, perform a second heating and a secondary stretching on the balloon to completely form the balloon.

[0114] In some embodiments, when the balloon tube 10 reaches the maximum stress state, control the heating sleeve temperature of the forming die 33 to rise; keep the first chuck 31 and the second chuck 32 at preset tensile force values respectively, which can be 270 N on the left and 260 N on the right; during the temperature rise process, control the movements of the first chuck 31 and the second chuck 32 respectively to adjust the balloon grip pattern depth, and at the same time make the wall thickness of the conical ends at both ends of the balloon thinner; maintain the working gas pressure until the to-be-formed area 11 of the balloon tube 10 completely adheres to the inner wall of the forming die 33.

[0115] In some embodiments, at a temperature of 134°C and a pressure of 16 bar, the first chuck 31 on the left and the second chuck 32 on the right are simultaneously stretched at a speed of 1.5 mm / s for 1 s, and then enter the next step.

[0116] Step S450, perform a third heating and high-temperature shaping on the formed balloon to remove internal stress.

[0117] In some embodiments, the third heating is to remove the internal stress of the balloon. The greater the temperature, the faster the internal stress is removed. Taking the absence of stress whitening of the balloon as the standard, in actual operation, the temperature and heating time of the third heating during the next balloon forming can be adjusted according to the appearance state of the balloon after it is removed from the mold.

[0118] In some embodiments, raise the heating sleeve temperature of the forming die 33 to a preset temperature higher than the second heating temperature, such as 144°C, and then reduce the working gas pressure to a preset pressure lower than the forming pressure; maintain the temperature and pressure to perform a shaping treatment on the balloon until there is no stress whitening phenomenon in the balloon, so that the size of the balloon will not shrink due to stress after it is removed from the forming die 33. Optionally, maintain it at a temperature of 144°C and a nitrogen pressure of 15 bar for 160 s, and then turn off the heating sleeve of the forming die 33 and continue with the next step.

[0119] Specifically, in the sizing stage, since the balloon has been fully formed, there is no need to apply too high a working gas pressure. Excessive pressure may cause minute seams of the forming mold to be inscribed on the balloon surface. In this stage, the stress whitening phenomenon is removed mainly by using the time-temperature equivalence principle of polymer materials, and the qualified standard is that there is no whitening phenomenon on the balloon surface.

[0120] Step S460: After the balloon is lowered to a predetermined temperature, it is demolded step by step.

[0121] Such as Figure 6 , in some embodiments, under the condition of maintaining the working gas pressure, a cooling medium is introduced into the heating jacket of the forming mold 33. After the balloon is cooled to the preset temperature, the working gas pressure is maintained, the first chuck 31 on the left side is opened, and the balloon tube 10 is semi-detached from the seal. At the same time, the connection between the balloon tube 10 and the hollow connector 21 is maintained to maintain the working gas pressure. Subsequently, the second chuck 32 on the right side is opened, and the first chuck 31 and the second chuck 32 are driven to move away from the forming mold 33 in sequence, wherein the moving speed of the second chuck 32 is greater than that of the first chuck 31; finally, the forming mold 33 is opened, the working gas pressure is released, and the formed balloon is taken out.

[0122] In some embodiments, the cooling medium is cooling water. Before introducing the cooling water into the forming mold 33, the heating state is first turned off, and the pressure is maintained at 15 bar until the temperature drops to 20 °C to prevent the balloon from contacting the forming mold 33 and contracting due to heat during or after mold opening.

[0123] In some embodiments, when the first chuck 31 is opened, the pressure inside the balloon cannot be relieved, and it is necessary to ensure that the balloon is pressurized and adheres to the balloon mold. At this time, there is still a large resistance between the sealing ring 24, the hollow connector 21 and the balloon tube 10. Specifically, the left pulling force value is set to 420 N. In the state where the cooling water is turned on, the pressure is maintained at 15 bar, and the forming mold 33 is closed, the first chuck 31 and the left cylinder are opened, and at the same time, it moves slowly at a speed of 5 mm / s so that the sealing ring 24 is separated from the balloon tube 10 and the hollow connector 21 is still connected to the balloon tube 10. The setting of the above 420 N pulling force value is much larger than the actual friction force value, and the purpose is to make the displacement of the first chuck 31 only controlled by speed and time to prevent the actual displacement from being interfered by a large frictional resistance.

[0124] In some embodiments, in the state where the cooling water is turned on, the pressure is maintained at 15 bar, and the forming mold 33 is closed, the second chuck 32 and the right cylinder are opened, and nitrogen is blown to cool the inside of the balloon. At this time, the hollow connector 21 can still provide nitrogen pressure.

[0125] In some embodiments, the first chuck 31 and the second chuck 32 are away from the forming die 33 to leave a position for the automatic opening of the forming die 33. When the hollow connector 21 can still provide partial pressure, the second chuck 32 first quickly disengages to avoid the balloon tube 10 hooking the second chuck 32 and damaging the appearance of the balloon.

[0126] In some embodiments, when the cooling water is turned on, the pressure is maintained at 15 bar, the forming die 33 is closed, and the first chuck 31 and the second chuck 32 are open, the first chuck 31 moves leftward at a speed of 80 mm / s to a position of 150 mm, and the second chuck 32 moves rightward at a speed of 100 mm / s to a position of 200 mm.

[0127] In some embodiments, when the cooling water is turned on, the nitrogen is turned off, and the first chuck 31 and the second chuck 32 are open, the forming die 33 is slowly opened and the balloon is taken out.

[0128] In some embodiments, after the balloon is taken out, it further includes the steps of draining the cooling water and reloading the materials to prepare for the next balloon forming procedure.

[0129] In some embodiments, during the whole process of balloon forming, if the equipment or product is damaged for any reason, the heating sleeve of the forming die can be cooled by introducing cooling water (to prevent scalding), and then the current program is terminated. After the equipment and materials return to normal, the materials can be reloaded and the forming program can be executed starting from step S410. Through this emergency treatment plan, the personal safety of the operators can be effectively protected, and at the same time, the loss caused by continuous production can be avoided.

[0130] Compared with the prior art, the non-compliant balloon forming method of this embodiment adopts a process combining three times of heating and segmented stretching. By precisely controlling the working gas pressure, stretching speed and heating temperature, the balloon is evenly stressed during the forming process, effectively avoiding quality problems such as uneven balloon wall thickness and inconsistent strength. Especially during the first stretching process, through the matching control of the working gas pressure and the stretching speed, and the adjustment of the balloon grip depth during the second stretching process, the dimensional accuracy and service performance of the balloon are ensured; in addition, the step-by-step demolding process is adopted, and the working gas pressure is maintained by keeping the connection between the balloon tube 10 and the hollow connector 21, effectively preventing the deformation of the balloon during the demolding process, and finally obtaining a non-compliant balloon with better appearance quality and performance.

[0131] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims, and all of them fall within the protection scope of the present invention.

Claims

1. A tooling fixture for balloon molding, characterized in that: It includes a sealing member, a hollow connecting member and a pair of clamping members; The clamping member is provided with a channel for accommodating the balloon tube, and the channel is in clearance with the balloon tube; the inner walls of the two clamping members are each provided with a conical surface, and the two conical surfaces are axially arranged and can move toward each other; The hollow connector is used to introduce working gas into the balloon tube, and its outer diameter is gap-matched with the inner diameter of the balloon tube; The seal cooperates with the space limited by the two conical surfaces; when the two conical surfaces move toward each other, the seal is squeezed to generate axial force, and the axial force is decomposed into radial compression force by cooperating with the conical surfaces, so that the balloon tube is in close contact with the hollow connector.

2. The fixture according to claim 1, characterized in that: The sealing member comprises a plurality of sealing rings sequentially arranged along the axial direction, the outer diameter of the sealing ring is smaller than the maximum inner diameter of the inner wall of the clamping member, and the inner diameter of the sealing ring is close to the outer diameter of the balloon tube.

3. The fixture according to claim 2, characterized in that: The sum of the cross-sectional areas of the multiple sealing rings is greater than the maximum cross-sectional area defined by the two conical surfaces and the outer surface of the balloon tube.

4. The fixture according to claim 1, characterized in that: The pair of clamping members is configured as a first clamping portion and a second clamping portion, which are nested and can move axially; The two tapered surfaces are respectively arranged at an end of the first clamping portion away from the second clamping portion and an end of the second clamping portion close to the first clamping portion.

5. The fixture according to claim 1, characterized in that: The angle between the conical surface and the axial direction is 30° to 45°.

6. A method for forming a non-compliant balloon, characterized in that: The following steps are involved: A first chuck is used to fix one end of the balloon tube, and a second chuck is used to fix the other end of the balloon tube, and the area to be formed of the balloon tube is placed in a forming mold; wherein the first chuck is configured as a fixture as described in any one of claims 1 to 5; The balloon tube is heated for the first time, and low-pressure working gas is introduced through the first clamp to maintain the preset temperature for a predetermined time; A working gas is introduced into the balloon tube, and the balloon tube is stretched for the first time in a process of gradually increasing pressure until the ultimate stress of the balloon tube is reached; Under the condition of maintaining the working gas pressure, heating the balloon for the second time and stretching the balloon for the second time to make the balloon fully formed; The formed balloon is heated for the third time and fixed at high temperature to remove internal stress; After the balloon is cooled to a predetermined temperature, demoulding is performed step by step.

7. The non-compliant balloon forming method according to claim 6, characterized in that: The step of fixing one end of the balloon tube with a first chuck, fixing the other end of the balloon tube with a second chuck, and placing the area to be formed of the balloon tube in a forming mold comprises: Install the left end of the balloon tube into the first chuck; The conical surfaces of the first clamping part and the second clamping part of the first clamping head are driven to move toward each other, so that the sealing member is squeezed to generate radial pressing force, thereby sealing and fixing the balloon tube and the hollow connecting member; The area to be formed of the balloon tube is placed in the forming mold, and gas is introduced into the heating jacket of the forming mold to keep the heating jacket in a dry state.

8. The non-compliant balloon forming method according to claim 6, characterized in that: The step of heating the balloon tube for the first time, introducing low-pressure working gas through the first chuck, and maintaining the temperature at a preset time includes: Controlling the temperature of the heating sleeve of the forming mold to rise to a preset temperature; While heating, low-pressure working gas is introduced into the balloon tube through the first clamp; The heating jacket is used to uniformly heat the area of ​​the balloon tube to be formed; Maintain the preset temperature for a predetermined time to soften the balloon tubing.

9. The method for forming a non-compliant balloon according to claim 8, characterized in that: The preset temperature is 90-130° C., the working gas is nitrogen, and the pressure of the working gas is lower than the pressure of balloon molding.

10. The non-compliant balloon forming method according to claim 8, characterized in that: The step of uniformly heating the area to be formed of the balloon tube by using the heating sleeve also includes: The balloon tubing is pre-stretched to reduce the wall thickness of the balloon.

11. The method for forming a non-compliant balloon according to claim 6, characterized in that: The step of introducing working gas into the balloon tube and stretching the balloon tube for the first time during the process of gradually increasing pressure until the ultimate stress of the balloon tube is reached includes: Introducing working gas below the molding pressure into the balloon tube; Control the working gas pressure to rise to the molding pressure at a preset slope; During the process of increasing working gas pressure, the first chuck and the second chuck are driven to move synchronously in opposite directions to axially stretch the balloon tube. The speed of axial stretching matches the speed of increasing working gas pressure until the area to be formed of the balloon tube reaches the limit stress and stops moving.

12. The non-compliant balloon forming method according to claim 11, characterized in that: After the step of introducing working gas into the balloon tube and performing a first stretching on the balloon tube during the process of gradually increasing pressure until the ultimate stress of the balloon tube is reached, the method further includes: Maintaining the working gas pressure, controlling the first chuck and the second chuck to respectively maintain a preset tension value; The preset tension value is maintained within the preset time to adjust the scratch depth of the balloon tube so that the area to be formed is fully expanded.

13. The method for forming a non-compliant balloon according to claim 6, characterized in that: The step of performing a second heating and a second stretching of the balloon while maintaining the working gas pressure to fully form the balloon includes: When the balloon tube reaches the maximum stress state, the temperature of the heating jacket of the molding die is controlled to increase; The first chuck and the second chuck are respectively maintained at preset tension values; During the temperature increase process, the movement of the first chuck and the second chuck is controlled respectively to adjust the depth of the balloon scratches and reduce the wall thickness of the tapered end of the balloon; The working gas pressure is maintained until the area to be formed of the balloon tube is completely attached to the inner wall of the forming mold.

14. The method for forming a non-compliant balloon according to claim 6, characterized in that: The step of heating the formed balloon for the third time and shaping it at high temperature to remove the internal stress includes: Raising the temperature of the heating jacket of the molding die to a preset temperature higher than the second heating temperature; Reduce the working gas pressure to a preset pressure lower than the molding pressure; Maintaining the temperature and pressure to shape the balloon until the balloon is free of stress whitening; Turn off the heating jacket of the forming mold.

15. The method for forming a non-compliant balloon according to claim 6, characterized in that: The step of lowering the balloon to a predetermined temperature and then demoulding the balloon in steps comprises: Under the condition of maintaining the working gas pressure, the cooling medium is introduced into the heating jacket of the forming mold; After the balloon is cooled to a preset temperature, the working gas pressure is maintained, the first chuck on the left is opened, and the balloon tube is semi-detached from the sealing member, while the balloon tube is kept connected to the hollow connector to maintain the working gas pressure; Open the second chuck chuck on the right; Driving the first chuck and the second chuck to move away from the forming die in sequence, wherein the moving speed of the second chuck is greater than that of the first chuck; Open the molding mold, release the working gas pressure, and take out the molded balloon.

16. The method for forming a non-compliant balloon according to claim 15, characterized in that: The step of opening the first chuck on the left side includes: driving the first clamp to move leftward at a preset speed to separate the balloon tube from the sealing member; Keep the balloon tubing connected to the hollow connector to maintain the working gas pressure.

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