A partitioned flexible liner replaceable cold isostatic pressing mold

Abstract

The utility model discloses a kind of replaceable cold isostatic pressing mould of partition flexible lining, belong to powder forming mould technical field.The mould includes shell, buffer layer being arranged in shell and flexible lining being detachably installed in the inside of buffer layer.It solves the problem of existing cold isostatic pressing mould lining replacement difficulty, high cost, product density unevenness.The utility model is characterized by: flexible lining is the component of independent replacement, preferably using wear-resistant inner layer and high-elastic outer layer Double-layer composite structure;Buffer layer uses the partition design of bottom thickness greater than sidewall thickness, to optimize pressure distribution;Shell outer surface is equipped with stress release groove to prolong life.The utility model realizes the quick replacement of flexible lining by modularization and optimization design, significantly reduces maintenance cost, while improving the density uniformity of pressing green body, and improve the overall durability of mould and the adaptability to different materials.

Description

Technical Field

[0001] This utility model relates to the field of powder molding die technology, and more specifically, to a die for cold isostatic pressing (CIP) molding of powder materials such as ceramic targets. Background Technology

[0002] Currently, cold isostatic pressing (CIP) technology applies isotropic ultra-high pressure to powder placed in a sealed container using a liquid medium, shaping it into a green body with a high initial density. This technology plays a crucial role in the preparation of materials such as powder metallurgy, high-performance ceramics, and cemented carbide, especially in the preparation of large-size, complex-shaped ceramic targets.

[0003] Currently, molds used for cold isostatic pressing typically employ a structure of "rigid outer mold + flexible inner mold". The rigid outer mold (shell) provides structural support and is generally made of metal; the flexible inner mold (liner) is in direct contact with the powder and undergoes elastic deformation under the action of a high-pressure liquid medium, uniformly transmitting pressure to the powder, and is usually made of elastomers such as rubber or polyurethane.

[0004] However, existing cold isostatic pressing molds have the following shortcomings: 1. High maintenance costs and short lifespan: Flexible liners are prone to fatigue, aging, hardening, or even cracking after long-term exposure to cyclic ultra-high pressure (usually hundreds of megapascals), leading to their failure. In contrast, the liner of a traditional mold is usually permanently fixed to the outer shell by means of bonding. Once the liner is damaged, it is often necessary to replace the entire mold or carry out complex repairs, which is costly and results in long downtime.

[0005] 2. Poor material compatibility: Different ceramic powder systems (such as oxides, nitrides, carbides, etc.) may have different chemical compatibility requirements for the lining material they come into contact with. Traditional molds with a single lining material are difficult to be compatible with all types of powders, and changing to a different powder may require replacing the entire mold, which lacks flexibility.

[0006] 3. Poor uniformity of product density: During the pressing process, due to the different constraints and force transmission paths of the bottom and side walls of the mold, the degree of densification of different parts of the powder may vary. Especially in the pressing of large blanks, this can easily lead to uneven density of the final product, affecting its sintering performance and the consistency of the final product.

[0007] Therefore, there is an urgent need to develop a new type of cold isostatic pressing mold with innovative structure, convenient maintenance, wide applicability, and the ability to improve the molding quality of products, so as to solve the technical problems existing in the above-mentioned technologies, such as "uneven density of blank, difficulty in demolding, and short mold life". Utility Model Content

[0008] The technical problem to be solved by this utility model is to provide a cold isostatic pressing mold to solve the problems in the prior art that the mold is prone to uneven density of the blank, difficulty in demolding, and short life of the mold itself (especially the flexible part) during the pressing process.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A partitioned, replaceable flexible-lined cold isostatic pressing mold includes a housing, a buffer layer, and a flexible liner. The housing provides overall rigid support. The buffer layer is disposed within the cavity of the housing. The core innovation lies in the flexible liner being designed as a detachable structure, allowing for quick installation inside the buffer layer and, together with the buffer layer, defining the mold cavity for receiving powder. This replaceable design enables operators to easily remove and replace the flexible liner when it wears out or needs to be replaced to accommodate different powders, significantly reducing maintenance costs and production downtime.

[0010] As a preferred embodiment, the flexible liner employs a double-layer composite structure. The inner layer, the side directly in contact with the powder, is made of a wear-resistant and chemically resistant material (such as fluororubber) to ensure chemical stability against various powders and a long service life. The outer layer is made of a highly elastic material (such as polyurethane), responsible for transmitting pressure and providing structural support. This composite structure balances durability and functionality.

[0011] As another preferred embodiment, the buffer layer adopts a partitioned thickness design, with the thickness of its bottom region being significantly greater than the thickness of its sidewall regions. This design is based on finite element analysis of pressure transmission. By increasing the thickness of the bottom buffer material, the pressure distribution can be effectively adjusted, compensating for the pressure transmission loss at the bottom caused by geometric constraints. This results in more uniform stress on the powder during the pressing process, significantly improving the density uniformity of the final blank.

[0012] As another preferred embodiment, the outer peripheral surface of the housing is provided with multiple stress relief grooves, typically longitudinal or circumferential grooves. These grooves can effectively interrupt the continuous stress transmission path, preventing the formation of stress concentration areas on the outer wall of the mold, thereby improving the fatigue resistance of the housing and extending the service life of the entire mold.

[0013] To enable rapid replacement of the flexible liner, the outer layer of the flexible liner is provided with a positioning and snap-fit ​​structure (such as a slot) that matches the inner wall of the buffer layer, and is sealed by a sealing element (such as an O-ring) to ensure that liquid media will not penetrate between the layers under high pressure.

[0014] The beneficial effects of this utility model are as follows: Reduce maintenance costs and improve production efficiency: The flexible liner can be disassembled and replaced independently and quickly. When it is worn or aged, only this part needs to be replaced, without replacing the entire mold. This significantly reduces costs and the replacement process is quick, reducing equipment downtime.

[0015] Improved product quality: The partitioned thickness design of the buffer layer optimizes the pressure distribution inside the mold, making the powder more evenly compressed and effectively improving the density uniformity and consistency of the pressed blank.

[0016] Enhanced applicability and flexibility: The flexible liner of different materials can be quickly replaced according to the chemical properties of different powders, so that one mold body can be adapted to multiple production tasks, thus enhancing the versatility and flexibility of the equipment.

[0017] Extending the overall lifespan of the mold: The double-layer composite liner structure enhances durability, while the stress relief grooves on the outer shell reduce the risk of metal fatigue, together extending the overall lifespan of the mold.

[0018] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present invention and, together with their description, serve to explain the principles of the present invention.

[0021] Figure 1 This is a cross-sectional view of the overall structure of one embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the double-layer composite structure of the flexible liner in this utility model.

[0023] Figure 3 This is a schematic diagram of the partitioned thickness structure of the buffer layer in this utility model.

[0024] Explanation of reference numerals in the attached figures: 10: Mold cavity 20: Outer shell 21: Stress relief groove 30: Buffer layer 31: Buffer layer sidewall area 32: Bottom area of ​​the buffer layer 40: Flexible liner 41: Inner layer (fluororubber layer) 42: Outer layer (polyurethane layer) 43: Positioning and locking structure 44: Seals. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0026] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0027] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0028] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0030] Please see Figures 1 to 3 This utility model provides a preferred embodiment of a cold isostatic pressing mold with a replaceable partitioned flexible liner.

[0031] like Figure 1 As shown, the mold comprises, from the outside in, an outer shell 20, a buffer layer 30, and a flexible liner 40. These three components are coaxially arranged and together form a mold for powder molding.

[0032] The outer shell 20 is the outermost structure of the mold, and its main function is to provide sufficient rigidity and strength under ultra-high pressure operating conditions to resist the enormous internal pressure and prevent permanent deformation of the mold. In this embodiment, the outer shell 20 is made of high-strength alloy steel (e.g., 40CrNiMo) through integral forging and precision machining. To further improve its fatigue resistance, multiple stress relief grooves 21 are machined on the outer peripheral surface of the outer shell 20, evenly distributed along the circumference. These longitudinal grooves can effectively alleviate the stress concentration phenomenon on the surface of the outer shell under high-pressure cyclic loading, thereby significantly extending the service life of the outer shell.

[0033] The buffer layer 30 is tightly disposed within the inner cavity of the outer casing 20. It is made of polyurethane material with good elasticity and compression resistance. The main function of the buffer layer 30 is to act as an intermediate medium for pressure transmission, transferring the pressure of the external liquid medium more gently and evenly to the internal flexible liner 40. Figure 3 As shown, a key design feature of this embodiment is the partitioned thickness design of the buffer layer 30. The thickness (T2) of its bottom region 32 is significantly greater than the thickness (T1) of its sidewall region 31. Specifically, the bottom thickness T2 can be set to 1.5 times the sidewall thickness T1. This design can compensate for the pressure transmission differences caused by the additional axial constraint on the bottom of the powder during the pressing process, making the pressure distribution in the entire mold cavity more uniform, thereby improving the density uniformity of the final blank.

[0034] The flexible liner 40 is one of the core components of this utility model. It is detachably installed inside the buffer layer 30. The flexible liner 40, the buffer layer 30, and the top cover (not shown) together form a mold cavity 10 for accommodating the powder to be pressed.

[0035] In this embodiment, the top cover 10 covers the opening of the outer casing 20 in a sealing manner. Specifically, the opening of the outer casing 20 extends upward to form an upper flange 21, and a lower flange 11 is correspondingly provided on the edge of the top cover 10. A sealing gasket (not shown) is provided between the upper flange 21 and the lower flange 11. By passing through the upper flange 21 and the lower flange 11 with several fastening bolts (not shown) and locking them together, a reliable mechanical connection and high-pressure seal between the top cover 10 and the outer casing 20 can be achieved. This structure ensures that in an external ultra-high pressure liquid environment, the liquid medium will not enter the interior of the outer casing 20 from the top of the mold, ensuring the normal operation of the powder drying and pressing process.

[0036] like Figure 2As shown, the flexible liner 40 employs a double-layer composite structure. The inner layer 41, which directly contacts the powder within the mold cavity 10, is made of fluororubber, which is wear-resistant and chemically stable, and can be up to 3 mm thick. This ensures that the mold can be used with various chemically reactive ceramic powders and is not easily worn by the powder. The outer layer 42, which is bonded to the inner layer 41 through processes such as co-extrusion or hot vulcanization, is made of highly elastic polyurethane and can be up to 5 mm thick. The polyurethane outer layer 42 is responsible for bearing and transmitting most of the pressure and maintaining the overall shape of the flexible liner 40.

[0037] To enable the flexible liner 40 to be detachable and quickly replaced, a positioning and locking structure 43 (e.g., an annular groove) is provided on the upper outer edge of the outer layer 42. This structure engages with corresponding protrusions or grooves on the inner wall of the buffer layer 30 to achieve precise axial and radial positioning. Simultaneously, a sealing element 44 (e.g., an O-ring) is provided at the locking point to ensure that external liquid media do not penetrate between the flexible liner 40 and the buffer layer 30 under pressures up to hundreds of megapascals, thus guaranteeing the effectiveness of pressure transmission and the safety of the system. When the flexible liner 40 needs to be replaced, the operator only needs to remove the top cover to easily remove the old flexible liner 40 from the buffer layer 30 and install the new liner. The entire process requires no special tools, is quick, and extremely convenient.

[0038] To achieve a reliable seal between the flexible liner 40 and the buffer layer 30 at the open end and to prevent powder from leaking between them during filling or pressing, this embodiment adopts a preferred snap-fit ​​sealing structure.

[0039] As attached Figure 3 As shown, an annular groove 31 is machined around the inner edge of the opening end of the buffer layer 30. Correspondingly, an annular flange 41 is integrally formed around the outer edge of the opening end of the flexible liner 40, the shape and size of which match the annular groove 31. At the bottom of the annular groove 31, the sealing element 44 is placed, which is preferably an O-ring rubber seal.

[0040] During assembly, the annular flange 41 of the flexible liner 40 is pressed firmly into the annular groove 31 of the buffer layer 30. During this process, the annular flange 41 compresses the seal 44, causing it to elastically deform and fill the tiny gap between the groove and the flange, thus forming a reliable radial seal. This structure not only provides excellent sealing but also facilitates easy assembly and disassembly, making it convenient to replace the flexible liner 40.

[0041] Working principle and pressure transmission mechanism: The working principle of this utility model is based on cold isostatic pressing (CIP) technology, and its working process is as follows: First, the powder is loaded into the flexible liner 40, and the top cover 10 is installed to completely seal the mold. Then, the entire mold is hoisted into the working cylinder of the cold isostatic press.

[0042] When the cold isostatic press is started, the liquid medium (such as water or oil) in the working cylinder is pressurized to an ultra-high pressure state (e.g., hundreds of megapascals). At this time, the ultra-high pressure liquid medium acts uniformly on the outer surface of the outer casing 20, forming an isotropic hydrostatic pressure.

[0043] The pressure transmission process is as follows: Although the outer shell 20 is a rigid structure, its main function is to act as a pressure vessel and sealing boundary, resisting the enormous external hydrostatic pressure and maintaining the overall structural stability of the mold, rather than relying on its own large elastic deformation to transmit pressure. Pressure transmission is achieved through the following chain mechanism: (1) The external high-pressure liquid acts on the outer surface of the shell 20. Due to the mechanical properties of the material, the pressure is transmitted to the inner wall of the shell 20, so that the inner wall surface bears a uniform surface pressure.

[0044] (2) The buffer layer 30 is made of an elastomer material such as polyurethane and is tightly attached to the inner wall of the outer shell 20. Therefore, the surface pressure on the inner wall of the outer shell 20 is directly and without damage transmitted to the buffer layer 30.

[0045] (3) Under great pressure, the buffer layer 30 will undergo a small amount of elastic compression and squeeze the flexible liner 40 in close contact with it.

[0046] (4) The flexible liner 40 undergoes elastic deformation (inner bulge) under the pressure of the buffer layer 30, and its inner surface applies pressure evenly to the powder inside.

[0047] In summary, the pressure transmission path is: "external liquid medium → outer shell → buffer layer → flexible liner → powder". This process achieves uniform three-dimensional compaction of the powder, resulting in a high-density, homogeneous preform. After pressing, the pressure is released, and the preform can be removed from the mold.

[0048] Furthermore, cold isostatic pressing (CIP) is not a traditional unidirectional mechanical extrusion, but rather an isotropic pressure field based on cold isostatic pressing (CIP). A liquid medium creates a uniform hydrostatic pressure outside the mold, which is transmitted layer by layer through a rigid outer shell, buffer layer, and flexible liner, acting on the powder to uniformly densify it in three dimensions. There is no piston-like displacement or powder flow throughout the process; therefore, it is an isotropic densification process rather than extrusion molding.

[0049] The work process is briefly described as follows: Install a new or clean flexible liner 40 into the buffer layer 30.

[0050] The pre-treated ceramic powder is loaded into the mold cavity 10 and sealed with the top cover.

[0051] The entire mold is hoisted into the working cylinder of the cold isostatic press.

[0052] Start the equipment, inject a liquid medium (such as water or oil) into the working cylinder and pressurize it.

[0053] The ultra-high pressure liquid medium acts evenly on the flexible liner 40 through the outer shell 20 and the buffer layer 30. The flexible liner 40 undergoes elastic deformation, transmitting the pressure to the powder inside, which is then pressed into a dense blank.

[0054] After holding and releasing the pressure, remove the mold, open the top cover, and you can obtain the formed ceramic blank.

[0055] In summary, this utility model, through its innovative replaceable double-layer flexible liner, partitioned thickness buffer layer, and shell structure with stress relief groove, successfully solves many pain points of the prior art, providing a mold solution for cold isostatic pressing of high-performance powder materials that is lower in cost, higher in efficiency, better in quality, and longer in life.

[0056] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. For those skilled in the art, various improvements and modifications can be made without departing from the design concept and principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

[0057] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A zoned flexible liner replaceable cold isostatic press mold characterized by, include: The outer shell has an inner cavity to provide overall rigid support; A buffer layer is disposed in the inner cavity of the outer shell to uniformly transmit pressure; A flexible liner is detachably installed inside the buffer layer and together with the buffer layer defines a mold cavity for containing powder.

2. The cold isostatic pressing mold according to claim 1, characterized by The flexible liner is a double-layer composite structure, comprising: The inner layer, facing the mold cavity, is made of a wear-resistant and chemically resistant material; The outer layer, which is compositely connected to the inner layer and in contact with the buffer layer, is made of a highly elastic material.

3. The cold isostatic pressing mold according to claim 2, characterized in that, The inner layer is a fluororubber layer, and the outer layer is a polyurethane layer.

4. The cold isostatic pressing mold according to claim 1, characterized by The buffer layer has a partitioned thickness structure, with the thickness of its bottom region being greater than the thickness of its sidewall regions.

5. The cold isostatic pressing mold according to claim 4, characterized in that The thickness of the bottom region of the buffer layer is 1.2 to 2.0 times the thickness of its sidewall region.

6. The cold isostatic pressing mold according to claim 1, characterized by The outer peripheral surface of the shell is provided with multiple stress relief grooves for dispersing stress.

7. The cold isostatic pressing mold according to claim 6, characterized in that The stress relief groove is a longitudinal groove distributed along the circumference of the outer shell.

8. The cold isostatic pressing mold according to claim 1, characterized in that, The outer layer of the flexible liner is provided with a positioning and snap-fit ​​structure that cooperates with the inner wall of the buffer layer, and a sealing element is provided at the joint between the flexible liner and the buffer layer to achieve rapid fixation and sealing of the flexible liner.

9. The cold isostatic pressing mold according to claim 8, characterized in that The positioning and snapping structure is an annular groove or a protrusion, and the sealing element is an O-ring.

10. The cold isostatic pressing mold according to claim 1, characterized by The outer shell is made of high-strength alloy steel, and the buffer layer is made of polyurethane material.

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