Balloon molding die and molding method

Abstract

This application relates to the field of medical devices, and particularly to a balloon molding mold and molding method. The balloon molding mold includes an intermediate mold and two end molds disposed at both ends of the intermediate mold. The intermediate mold has an internal intermediate chamber for molding the middle section of the balloon, and the two end molds have end chambers for molding the proximal and distal ends of the balloon, respectively. In the assembled state, the two end chambers communicate with the intermediate chamber to form a molding cavity. Each end of the intermediate mold has a recessed locking hole on its two side surfaces. One end of each end mold is locked into the locking hole. An venting groove is formed on the wall of the locking hole and / or on the outer surface of the portion of the end mold locked into the locking hole, connecting the molding cavity to the outside. The balloon molding mold and molding method can effectively improve the uniformity of the wall thickness of the balloon after molding.

Description

Technical Field

[0001] This application relates to the field of medical devices, and in particular to a balloon molding mold and molding method. Background Technology

[0002] Medical balloons, as the core component of balloon catheters, play a crucial role in angioplasty. They are responsible not only for the pre-dilation and shaping of blood vessels but also for the critical task of stent delivery. The performance requirements for medical balloons during use include: maintaining shape stability under rated pressure, possessing sufficient flexibility to accommodate the passage through tortuous blood vessels, and having sufficient rigidity to support the stent.

[0003] The aforementioned performance requirements essentially mandate that the molded balloon maintain a relatively uniform wall thickness. However, the balloon molding process involves several dynamically changing process parameters, such as temperature, stretching speed, and inflation pressure. The settings of these parameters can all affect the uniformity of the wall thickness, making it difficult to pinpoint which specific parameter settings are causing uneven wall thickness. Currently, the production success rate of medical balloons is not ideal, with an actual success rate of only about 50%, and it decreases as the balloon length increases. Summary of the Invention

[0004] This application provides a balloon molding mold and molding method, which can effectively improve the uniformity of the wall thickness of the balloon after molding.

[0005] According to a first aspect of this application, a balloon molding mold is provided, including an intermediate mold and two end molds disposed at both ends of the intermediate mold. The intermediate mold has an intermediate chamber for forming the middle section of the balloon, and the two end molds have end chambers for forming the proximal and distal ends of the balloon, respectively. In the assembled state, the two end chambers communicate with the intermediate chamber to form a molding cavity. Each of the two ends of the intermediate mold has a recessed locking hole, and one end of the end mold is locked in the locking hole. An exhaust groove communicating with the molding cavity to the outside is formed on the wall of the locking hole and / or on the outer surface of the portion of the end mold locked in the locking hole.

[0006] In one embodiment, the venting groove includes: a first groove segment formed on the bottom wall of the hole and / or on the end face of the end mold adjacent to the bottom wall of the hole, and a second groove segment formed on the side wall of the hole and / or on the outer peripheral surface of the end mold, one end of the second groove segment communicating with the first groove segment, and the other end extending out of the hole along the direction of the side wall of the hole.

[0007] In one embodiment, the venting groove is formed on the end mold.

[0008] In one embodiment, the balloon forming mold further includes two connectors respectively disposed at both ends of the two end molds. A connecting hole is recessed on one side of the connector. The portion of the end mold that extends beyond the fixing hole is fixedly received in the connecting hole. The connector has a tube blank cavity that communicates with the end chamber and is used to accommodate the tube blank through which it passes.

[0009] In one embodiment, the connector is made of PEEK material, and / or the end chamber includes a tapered cavity for receiving a tapered segment of the balloon, and a circular tube cavity that is equal in diameter to and communicates with the small-diameter end of the tapered cavity, the tube blank cavity being equal in diameter to and aligned with the circular tube cavity.

[0010] In one embodiment, the first groove segment is configured as a semi-circular groove with a semi-circular cross-section having a diameter of 0.4mm-0.5mm, and / or, the first groove segment is configured as 3 or 4, and all the first groove segments are evenly distributed circumferentially.

[0011] In one embodiment, the second groove segment is configured as a triangular groove or a polygonal groove with a triangular cross section or a polygonal cross section, the area of ​​which is greater than or equal to the area of ​​the semi-circular cross section.

[0012] In one embodiment, the intermediate mold is made of copper, brass, or beryllium copper, and / or the end mold is made of copper, brass, or beryllium copper.

[0013] In one embodiment, the axial length of the intermediate chamber is 40mm±5mm, 60mm±5mm, 80mm±5mm, 120mm±5mm, 150mm±5mm, or 200mm±5mm.

[0014] According to a second aspect of this application, a method for forming a balloon is also provided, the method utilizing the above-described balloon forming mold to achieve the stretching and forming of a balloon, the method comprising the following steps:

[0015] S1 stretches the tube blank once to form a bubble at the appropriate position on the tube blank;

[0016] S2 Place the bubble into the intermediate cavity of the balloon forming mold, and introduce nitrogen into the tube blank to maintain the inside of the bubble at a low pressure.

[0017] S3 Heat the balloon molding mold until the internal temperature reaches 110°C;

[0018] S4 Increase the pressure inside the material bubble to maintain a high-pressure state inside the material bubble. Under the high-pressure state, perform an initial stretching at the same speed on both ends of the tube blank, wherein: the stretching speed is controlled at 80mm / s-120mm / s, and the stretching distance is set to 0.6-1.5 times the length of the material bubble;

[0019] S5. The two ends of the tube blank are stretched at the same speed in a second stretch, wherein the stretching speed is controlled between 1 mm / s and 20 mm / s, the stretching distance is set between 1 mm and 20 mm, and during the first stretch and the second stretch, the gas in the forming cavity is discharged through the exhaust groove under the compression of the material bubble.

[0020] S6 Under the high pressure state, the internal temperature of the balloon forming mold is increased and maintained for a preset time so that the shrinkage of the formed balloon after cooling and demolding does not exceed 10%.

[0021] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0022] One end of each of the two end molds is respectively fitted into the retaining holes on both ends of the middle mold, thus forming an integral balloon molding mold through assembly. According to the deformation law of the bubble during expansion and stretching in the molding cavity, the gas in the molding cavity tends to accumulate at the junction of the end mold and the middle mold. Setting an venting groove at this location can eliminate the trapped gas area in the molding cavity, thereby ensuring the smooth molding of the balloon.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a balloon produced by a balloon molding die according to an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the assembly structure of a balloon molding mold according to an embodiment of this application;

[0026] Figure 3 yes Figure 2 The diagram shows a half-section of the intermediate mold in the balloon molding mold.

[0027] Figure 4 This is a schematic diagram of the assembly structure of the middle mold and connecting parts of a balloon molding mold according to an embodiment of this application;

[0028] Figure 5 yes Figure 4 The diagram shows a half-section of the assembled structure;

[0029] Figure 6aThis is a schematic diagram of the tube blank before stretching used in the forming method of an embodiment of this application;

[0030] Figure 6b yes Figure 6a A schematic diagram of the structure of the tube blank after stretching to form a bubble;

[0031] Figure 6c It is Figure 6b Insert the tube blank containing the material bubble. Figure 2 A schematic diagram of the balloon molding process;

[0032] Figure 6d This is a schematic diagram of the state of the tube blank in the balloon forming mold during the initial stretching at both ends of the connector. In the diagram, the material bubble on the tube blank gradually extends towards the two end molds.

[0033] Figure 6e This is a schematic diagram showing the state of the tube blank in the balloon forming mold after secondary stretching. In the diagram, the material bubble has already formed. Figure 1 The basic shape of the balloon is shown in the figure.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100. Intermediate mold; 11. Intermediate cavity; 12. Insertion hole; 121. Bottom wall of the hole; 122. Side wall of the hole;

[0036] 200. End mold; 21. End chamber; 211. Conical cavity; 212. Circular tube cavity; 22. Exhaust groove; 221. First groove section; 222. Second groove section;

[0037] 300. Connector; 31. Tube blank cavity; 32. Connecting hole;

[0038] 400, tube blank; 41, material bubble;

[0039] 500, Trapped Gas Zone;

[0040] 01. Middle section; 02. Tapered section; 03. Pipe pin. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The modes described in the following exemplary embodiments do not represent all modes consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0042] It should be understood that the terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0043] The embodiments of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments can be combined with each other.

[0044] The balloon molding mold and molding method disclosed in this application are aimed at... Figure 1 The manufacturing process of the balloon is shown. The balloon includes a middle section 01, two tapered sections 02, and two tube ends 03. The middle section 01 is generally cylindrical, and its length L is also called the effective working length of the balloon. The left tapered section 02 and the left tube end 03 together form the distal end of the balloon; correspondingly, the right tapered section 02 and the right tube end 03 together form the proximal end of the balloon.

[0045] generally, Figure 1 The balloon shown requires at least two stretching operations on the tubular blank during processing to achieve the required balloon structure in terms of wall thickness and shape. However, in practice, it was found that the success rate of balloon production significantly decreased as the balloon length increased. The inventors made targeted attempts to adjust process parameters such as mold heating temperature, stretching speed, and inflation pressure, but the results were unsatisfactory. In some failed products, the balloon wall thickness was uneven across different parts, making it impossible to achieve the expected folding effect during later balloon folding. Some failed products also suffered localized damage at the middle section 01, or burst after inflation due to excessively thin walls in certain areas.

[0046] After repeatedly adjusting the process parameters without significantly improving the success rate, the inventors, through extensive trials and verifications, discovered that the key issue might lie in the structural rationality of the molding die. Specifically, the balloon molding process can be broadly divided into two parts: one is stretching the tube blank to form a bubble; the other is transferring the bubble-bearing tube blank into the balloon molding die for stretching and inflation molding. During the aforementioned two stretching processes of the tube blank, a certain amount of gas is introduced into the tube blank to cause the bubble to expand within the die cavity. Combined with the stretching and the shape of the die cavity, the final shape... Figure 1 The image shows a balloon. However, as the bubble swells, the air originally inside the mold cavity cannot be expelled as expected and in line with the rate of bubble swelling. This air becomes trapped inside the mold cavity, ultimately leading to the failure of the balloon molding process.

[0047] To address this problem, this application first provides a balloon molding mold. For example... Figure 2As shown, the balloon molding mold includes an intermediate mold 100 and two end molds 200 disposed at both ends of the intermediate mold 100. Wherein: Figure 2 Based on the combination Figure 3 As shown, the interior of the intermediate mold 100 is provided with a container for holding... Figure 1 The intermediate chamber 11 formed by the middle section 01 of the balloon is shown.

[0048] exist Figure 2 Based on the combination Figure 5 As shown, the end mold 200 is provided with a container for holding Figure 1 The distal and proximal end chambers 21 of the balloon are shown. Specifically, as... Figure 2 and Figure 5 As shown, the end chamber 21 includes a tapered cavity 211 for accommodating the tapered segment 02 during forming, and a circular tube 212 that is equal in diameter to and communicates with the small-diameter end of the tapered cavity 211. Figure 2 In the assembled state shown, the intermediate chamber 11 and the two end chambers 21 are connected to form a connection with Figure 1 A shaping cavity that adapts to the shape of the balloon.

[0049] Combination Figure 2 and Figure 3 As shown, both ends of the intermediate mold 100 have recessed mounting holes 12, each including a bottom wall 121 and a side wall 122. One end of the end mold 200 is fitted into the mounting hole 12, and in the assembled state, the end face of one end of the end mold 200 abuts against the bottom wall 121, and its outer circumferential surface is either interference-fitted with the side wall 122 or fitted and fixed by other means. Under this assembly relationship, the inner walls of the intermediate chamber 11 and the two end chambers 21 can maintain continuity, which is beneficial to ensure the correct shaping of the balloon.

[0050] An venting groove 22, connecting the internal forming cavity to the external, is formed on the wall of the fixing hole 12 and / or on the outer surface of the portion of the end mold 200 that is fixed to the inner part of the fixing hole 12. Figure 2 Based on reference Figure 6d As shown, during the forming process of bubble 41, as both ends of bubble 41 approach the end chamber 21, the gas originally in the forming cavity is squeezed into the trapped gas area 500 shown in the figure by bubble 41. The venting groove 22 is used to discharge the gas in the trapped gas area 500. In this way, bubble 41 can smoothly expand in the forming cavity until the bubble wall fits against the inner wall of the end chamber 21, thereby forming... Figure 1 The balloon product shown in the figure has a uniform wall thickness across its various parts.

[0051] Combination Figure 3 , Figure 4 and Figure 5As shown in the illustrated embodiment, the venting groove 22 is formed on the end mold 200 and includes a first groove segment 221 located on the end face of the end mold 200 adjacent to the bottom wall 121 of the hole, and a second groove segment 222 formed on the outer peripheral surface of the end mold 200. One end of the second groove segment 222 communicates with the first groove segment 221, and the other end extends along the direction of the hole sidewall 122 to the outside of the fixing hole 12. In other embodiments, the venting groove 22 may also be provided on... Figure 3 The venting groove 22 is located on the intermediate mold 100 and specifically on the wall of the fixing hole 12. Specifically, the first groove segment 221 is formed on the bottom wall 121 of the hole, and the second groove segment 222 is formed on the side wall 122 of the hole. Alternatively, the two groove segments of the venting groove 22 can be formed on the end mold 200 and the intermediate mold 100 respectively, as long as they can connect the internal molding cavity to the outside.

[0052] Generally speaking, Figure 1 The shape and size of the middle segment 01 of the balloon shown are the most critical, as this segment is the effective working section that directly contacts and dilates blood vessels. Its shape must be prioritized during molding. By creating the venting groove 22 on the end mold 200, the molding area of ​​the middle segment 01 can be avoided, eliminating any potential impact of the venting groove 22 on balloon molding. Simultaneously, since the venting groove 22 on the end mold 200 is embedded within the fixing hole 12, creating the venting groove 22 there has minimal impact on the structural strength of the end mold 200, whereas creating it on the fixing hole 12 might weaken the strength of both ends of the middle mold 100 to some extent.

[0053] At the same time, using a three-section assembly to form an integral balloon molding mold also facilitates the design and manufacture of the venting groove 22. For example, the venting groove 22 can be machined on the end mold 200 and / or the intermediate mold 100 before assembly, and then assembled to form a continuous molding cavity.

[0054] refer to Figure 4 As shown, the first groove segment 221 can be configured as a semi-circular groove with a semi-circular cross-section of 0.4mm-0.5mm in diameter. Furthermore, three or four first groove segments 221 are evenly distributed circumferentially, allowing the gas in the trapped gas zone 500 to be discharged more evenly and smoothly, which is beneficial to the balloon formation process. The second groove segment 222 can be configured as a triangular or polygonal groove with a triangular or polygonal cross-section, and the area of ​​this triangular or polygonal cross-section is 1-1.5 times the area of ​​the semi-circular cross-section of the first groove segment 221. It should be understood that the triangular or polygonal cross-section referred to here is not a strict geometric concept of a triangle or polygon, but rather an approximation of that shape; that is, the sides are not strictly straight. Figure 4As shown, the bottom of the second groove segment 222 has a slight curvature due to processing and other reasons. It should be understood that, without affecting the balloon formation, the venting groove 22 can be made as deep as possible. The second groove segment 222 is located in the corresponding position inside the embedding hole 12. This position is not the part where the balloon is formed, but the connection between the end mold 200 and the intermediate mold 100. Therefore, by making the area of ​​the second groove segment 222 relatively large and the groove depth deeper, it is possible to ensure smooth venting while avoiding affecting the balloon formation.

[0055] exist Figure 2 Based on the combination Figure 4 and Figure 5 As shown, the balloon molding mold also includes two connectors 300 respectively disposed at both ends of the two end molds 200. The connector 300 is made of PEEK material and has a connecting hole 32 recessed on the side of the end adjacent to the end mold 200, and the part of the end mold 200 that extends beyond the fixing hole 12 is fixedly received in the connecting hole 32.

[0056] The connector 300 has a blank cavity 31 that communicates with the end chamber 21 and is used to accommodate the blank. The blank cavity 31 in the connector 300 is set with the same diameter and aligned with the aforementioned circular cavity 212 in the end mold 200. In this way, during stretching and inflation to form a balloon, the blanks at both ends of the balloon sequentially extend through the circular cavity 212 and the blank cavity 31. Thus, the blank cavity 31 is equivalent to extending the circular cavity 212 along the stretching direction of the blank, which ensures that the forming shape and size of the tube feet 03 in the circular cavity 212 are more stable.

[0057] In some embodiments, to ensure good thermal conductivity of the balloon molding mold during heating and to maintain a uniform temperature across the mold, the intermediate mold 100 and the end mold 200 can be made of copper, brass, or beryllium copper. Furthermore, to further ensure good thermal conductivity between the intermediate mold 100 and the end mold 200, both can be made of the same material, for example, both can be made of copper. In other embodiments, the intermediate mold 100 can be made of copper, while the end mold 200 can be made of brass or beryllium copper.

[0058] Combination Figure 1 and Figure 2 As shown, in one embodiment, the axial length of the intermediate chamber 11 is 40mm±5mm, 60mm±5mm, 80mm±5mm, 120mm±5mm, 150mm±5mm, or 200mm±5mm. This axial length corresponds to... Figure 1The length L of the middle section 01 of the balloon. A balloon with a length of 150mm or 200mm is considered a long balloon. Compared to short balloons with a length of less than 30mm, the success rate of balloon formation is lower. The reason for this is that more gas needs to be expelled from the forming cavity during the stretching of the balloon. This gas accumulates in the trapped gas area and cannot be expelled in time, affecting the balloon formation process. However, with the balloon forming mold provided in this application, the venting groove 22 allows the gas in the forming cavity to be expelled in time during the forming process of the middle section 01 of the balloon. Therefore, the trapped gas area is eliminated, and the balloon's swelling and elongation are no longer compressed by the gas in the forming cavity, resulting in smoother formation. The wall thickness of the formed balloon tends to be uniform throughout.

[0059] refer to Figures 6a to 6e As shown, this application also provides a method for forming a balloon using the balloon forming mold in any of the above embodiments. The forming method includes the following steps:

[0060] S1 pair Figure 6a The tube blank 400 is stretched once to form a bubble 41 at an appropriate position on the tube blank 400. The tube blank 400 after this first stretching is formed as follows: Figure 6b As shown;

[0061] S2 as Figure 6c As shown, the bubble 41 is placed in the intermediate chamber 11 of the balloon forming mold, and nitrogen gas is introduced into the tube blank 400 to keep the inside of the bubble 41 in a low-pressure state.

[0062] S3 heats the balloon molding mold until the internal temperature reaches 110°C;

[0063] S4 Reference Figure 6d As shown, the pressure inside the material bubble 41 is increased to maintain a high-pressure state inside the material bubble 41. Under this high-pressure state, the two ends of the tube blank 400 are subjected to a uniform initial stretching, wherein: the stretching speed is controlled at 80mm / s-120mm / s, and the stretching distance is set to 0.6-1.5 times the length of the material bubble;

[0064] S5 performs a second, uniform-speed stretching process on both ends of the 400mm tube blank, wherein the stretching speed is controlled between 1mm / s and 20mm / s, and the stretching distance is set between 1mm and 20mm. Furthermore, as... Figures 6d to 6eAs shown, during the initial and secondary stretching processes, the gas trapped in the gas trapping zone 500 within the molding cavity, compressed by the bubble 41, is expelled through the venting groove 22 as the bubble 41 expands. The direction of expulsion is indicated by the arrow in the figure. After the gas trapping zone 500 is eliminated, the bubble wall of the bubble 41 can fully fit the inner wall of the end chamber 21 within the end mold 200. In particular, the fit between the bubble 41 and the inner wall within the conical cavity 211 is even better, resulting in a better molding effect for the conical section 02 of the balloon.

[0065] S6 Under the aforementioned high-pressure condition, the internal temperature of the balloon molding mold is increased and maintained for a preset time so that the shrinkage of the formed balloon after cooling and demolding does not exceed 10%.

[0066] In one embodiment, such as Figure 6c As shown, when the bubble 41 is placed into the intermediate chamber 11 in step S2, the bubble 41 is arranged in the center of the intermediate chamber 11 as much as possible.

[0067] Depending on the material of the balloon or tube blank, the aforementioned increased low-pressure and high-pressure states have slight differences. For example, when using tube blanks made of TPU, PEBAX, or PA, the inflation pressure in the low-pressure state is generally 25-35 bar, while the pressure in the high-pressure state is 1-3 bar higher than that low-pressure state. When using tube blanks made of PET, or tube blanks made of PA but with increased wall thickness, the inflation pressure in the low-pressure state can be selected as 30-40 bar, and the pressure in the high-pressure state is also 1-3 bar higher than that low-pressure state.

[0068] Furthermore, in the initial stretching of step S4, material accumulation or localized insufficient radial dimensions may occur at both ends of the bubble 41. Therefore, a secondary stretching in step S5 is necessary to ensure that the bubble wall adheres tightly to the inner wall of the molding cavity under high pressure, and to effectively reduce the wall thickness of the conical segment 02 and the middle segment 01. The speed and distance of this secondary stretching are significantly lower than the initial stretching. This is mainly because the primary purpose of the secondary stretching is to extend the areas where material accumulation exists and to ensure that the bubble 41 ultimately adheres completely to the inner wall of the molding cavity. Excessive speed or excessive stretching distance in the secondary stretching can easily cause the bubble wall to break. Conversely, insufficient speed or excessively short stretching distance in the primary stretching can lead to insufficient expansion of the bubble 41, affecting the secondary stretching process.

[0069] In one embodiment, when manufacturing a non-compliant balloon using a tube blank made of nylon 12 or PEBAX material, the inflation pressure in the low-pressure state can be selected as 26 bar. When switching to the high-pressure state, the pressure is increased by approximately 3 bar by changing the nitrogen inflation rate. During the initial stretching, the end of the tube blank extending from the connector 300 is clamped using a clamp, and both ends are stretched at a constant speed of 70 mm / s, with the stretching distance controlled at 35 mm. During the second stretching, the stretching speed is adjusted to 10 mm / s, and the stretching distance is controlled at 5 mm.

[0070] In step S6, the temperature of the molding die after heating and the duration of maintaining that temperature vary depending on the material of the bulb or tube blank. Specifically: when using a TPU tube blank, the setting temperature can be set to 100°C-120°C, and the holding time is selected as 40s-60s; when using a PEBAX tube blank, the setting temperature can be set to 105°C-125°C, and the holding time is selected as 60s-90s; when using a PA tube blank, the setting temperature can be set to 120°C-140°C, and the holding time is selected as 80s-100s; when using a PET tube blank, the setting temperature can be set to 125°C-145°C, and the holding time is selected as 90s-110s.

[0071] If the temperature in step S6 is too high, the tube blank material may melt and stick to the inner wall of the molding cavity, causing a film to adhere. Even if the demolding is successful, there will be a local wall thickness reduction at the location where the film has adhered, which may cause the balloon to burst during the subsequent pressure test.

[0072] If the shrinkage of the product exceeds 10% after cooling and demolding, the dimensional accuracy of the balloon will be uncontrollable, making it difficult to meet the requirements for subsequent use.

[0073] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Although this application has disclosed preferred embodiments as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A balloon forming mold, characterized in that, The system includes an intermediate mold (100) and two end molds (200) disposed at both ends of the intermediate mold (100). The intermediate mold (100) has an intermediate chamber (11) for forming the middle section of the balloon. The two end molds (200) have end chambers (21) for forming the proximal and distal ends of the balloon, respectively. In the assembled state, the two end chambers (21) communicate with the intermediate chamber (11) to form a forming cavity. The intermediate mold (100) has recessed mounting holes (12) on both sides. One end of the end mold (200) is fixed in the mounting hole (12). The mounting hole (12) and / or the outer surface of the part of the end mold (200) that is fixed in the mounting hole (12) are provided with venting grooves (22) that connect the molding cavity to the outside.

2. The balloon molding mold according to claim 1, characterized in that, The venting groove (22) includes: a first groove segment (221) formed on the bottom wall (121) of the embedded hole (12) and / or on the end face of the end mold (200) adjacent to the bottom wall (121) of the hole, and a second groove segment (222) formed on the side wall (122) of the hole (12) and / or on the outer peripheral surface of the end mold (200), one end of the second groove segment (222) communicating with the first groove segment (221), and the other end extending out of the embedded hole (12) along the direction of the side wall (122).

3. The balloon forming mold according to claim 2, characterized in that, The venting groove (22) is formed on the end mold (200).

4. The balloon forming mold according to claim 3, characterized in that, The balloon forming mold also includes two connectors (300) respectively disposed at both ends of the two end molds (200). A connecting hole (32) is recessed on one side of the connector (300). The part of the end mold (200) that extends beyond the fixing hole (12) is fixedly received in the connecting hole (32). A tube blank cavity (31) is opened in the connector (300) that communicates with the end chamber (21) and is used to accommodate the tube blank through which it passes.

5. The balloon forming mold according to claim 4, characterized in that, The connector (300) is made of PEEK material, and / or the end chamber (21) includes a conical cavity (211) for receiving the conical segment of the balloon, and a circular tube cavity (212) that is equal in diameter to and communicates with the small-diameter end of the conical cavity (211), and the tube blank cavity (31) is equal in diameter to and aligned with the circular tube cavity (212).

6. The balloon molding mold according to claim 2 or 3, characterized in that, The first groove segment (221) is configured as a semi-circular groove with a semi-circular cross section with a diameter of 0.4mm-0.5mm, and / or, the first groove segment (221) is configured as 3 or 4, and all the first groove segments (221) are evenly distributed along the circumference.

7. The balloon forming mold according to claim 6, characterized in that, The second groove segment (222) is configured as a triangular groove or a polygonal groove with a triangular cross section or a polygonal cross section, wherein the area of ​​the triangular cross section or the polygonal cross section is greater than or equal to the area of ​​the semi-circular cross section.

8. The balloon forming mold according to claim 7, characterized in that, The intermediate mold (100) is made of copper, brass or beryllium copper, and / or the end mold (200) is made of copper, brass or beryllium copper.

9. The balloon molding mold according to claim 1, characterized in that, The axial length of the intermediate chamber (11) is 40mm±5mm, 60mm±5mm, 80mm±5mm, 120mm±5mm, 150mm±5mm or 200mm±5mm.

10. A method for forming a balloon, wherein the forming method utilizes the balloon forming mold according to any one of claims 1-9 to achieve the stretching and forming of the balloon, characterized in that, The molding method includes the following steps: S1 stretches the tube blank once to form a bubble at the appropriate position on the tube blank; S2 Place the bubble into the intermediate cavity of the balloon forming mold, and introduce nitrogen into the tube blank to maintain the inside of the bubble at a low pressure. S3 Heat the balloon molding mold until the internal temperature reaches 110°C; S4 Increase the pressure inside the material bubble to maintain a high-pressure state inside the material bubble. Under the high-pressure state, perform an initial stretching at the same speed on both ends of the tube blank, wherein: the stretching speed is controlled at 80mm / s-120mm / s, and the stretching distance is set to 0.6-1.5 times the length of the material bubble; S5. The two ends of the tube blank are stretched at the same speed in a second stretch, wherein the stretching speed is controlled between 1 mm / s and 20 mm / s, the stretching distance is set between 1 mm and 20 mm, and during the first stretch and the second stretch, the gas in the forming cavity is discharged through the exhaust groove under the compression of the material bubble. S6 Under the high pressure state, the internal temperature of the balloon forming mold is increased and maintained for a preset time so that the shrinkage of the formed balloon after cooling and demolding does not exceed 10%.

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