Isostatic pressing forming die and system for ceramic tube

Abstract

The embodiment of the utility model discloses a ceramic tube isostatic pressing forming mold and system. The mold comprises a rigid shell which is provided with an inner cavity, and the top and the bottom of the rigid shell are open. The rigid inner mold is arranged in an inner cavity of the rigid shell; the flexible sleeve is arranged between the rigid shell and the rigid inner mold; an accommodating cavity for accommodating ceramic powder can be formed between the flexible sleeve and the rigid inner mold; and the sealing element is used for blocking the bottom of the accommodating cavity. According to the forming system, the rigid shell, the flexible sleeve and the rigid inner mold are coaxial, ceramic powder filled into the containing cavity in a vibration mode is more uniform and compact, and therefore the straightness and wall thickness consistency of the ceramic tube blank are improved, meanwhile, after the ceramic tube is demolded, the rigid inner mold is easy to demold after isostatic pressing forming, and the forming quality is improved. The ratio of the length to the outer diameter of the manufactured ceramic tube can exceed 50, and the inner diameter of the manufactured ceramic tube can reach 3mm.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic tube preparation, and more specifically, to an isostatic pressing mold and system for ceramic tubes. Background Art

[0002] The corona pre-ionization electrode in the gas excimer laser usually uses a ceramic tube as the insulating medium. The ratio of the length of the ceramic tube to its diameter is large, and its length reaches 600-700mm. The ratio of the length to the outer diameter of the ceramic tube exceeds 50. In the existing technology, for such ceramic tubes, extrusion molding is usually adopted. That is, ceramic powder is first mixed with a large amount of liquid adhesive to form a ceramic mud, and then the ceramic mud is placed in a mold. It is extruded from the mold under a certain pressure to obtain a ceramic tube blank. However, due to the special application environment of this type of ceramic tube, particularly high requirements are placed on the purity of the ceramic tube itself and the content of certain impurities. In addition, the extrusion molding production method requires the use of a large amount of adhesive, and it is difficult to control the impurity content of the ceramic tube product. At the same time, a large number of pores are likely to remain inside the formed ceramic tube blank, affecting the plasma and chemical corrosion resistance of the ceramic tube, and thus affecting the service life. Utility Model Content

[0003] The purpose of the present utility model is to provide a ceramic tube isostatic pressing die and system to solve at least one of the above technical problems.

[0004] In order to achieve at least one of the above objectives, the present application adopts the following technical solutions:

[0005] The first aspect of the present application provides a ceramic tube isostatic pressing die, comprising

[0006] a rigid housing having an interior cavity and open top and bottom;

[0007] a rigid inner mold for being disposed in the inner cavity of the rigid outer shell;

[0008] a flexible sleeve for being disposed between the rigid outer shell and the rigid inner mold;

[0009] The flexible sleeve and the rigid inner mold may form a receiving cavity for receiving ceramic powder; and

[0010] A sealing member is used to seal the bottom of the accommodating cavity.

[0011] Optionally, the top of the flexible sleeve may extend to the outside of the top of the rigid shell;

[0012] The length of the rigid inner mold is greater than the length of the rigid outer shell.

[0013] Optionally, the mold further comprises a filler member provided with a material passing through hole, the outer diameter of which is set to be in close contact with the inner wall of the rigid shell through the flexible sleeve.

[0014] Optionally, the sealing member includes a slot at the center thereof for inserting the rigid inner mold.

[0015] Optionally, the rigid shell includes a shell body; and

[0016] a shell connecting portion located at the bottom side of the shell main body and communicating with the main body;

[0017] The radial dimension of the shell connecting portion is greater than the radial dimension of the shell main body portion.

[0018] Optionally, the flexible sleeve comprises a flexible main body portion; and

[0019] a flexible connecting portion located at the bottom side of the flexible main body and communicating with the flexible main body;

[0020] The radial dimension of the flexible connection portion is greater than the radial dimension of the flexible main body portion.

[0021] The second aspect of the present application provides a ceramic tube isostatic pressing system, comprising

[0022] The ceramic tube isostatic pressing die provided in the first aspect above;

[0023] a vibration table, comprising a table surface for fixing and supporting the isostatic pressing mold for the ceramic tube; and

[0024] An eccentric motor for vibrating the vibration table.

[0025] Optionally, the bottom edge of the rigid shell extends outward to form an extension plate;

[0026] The extension plate may be fixedly connected to the vibration table via a fixing member.

[0027] The beneficial effects of this application are as follows:

[0028] 1. In the ceramic tube isostatic pressing die of the present application, the flexible sleeve is positioned between the rigid outer shell and the rigid inner mold, thereby providing a buffer for the ceramic powder during its placement into the accommodating cavity. The rigid outer shell supports the flexible sleeve without causing deformation, ensuring the straightness of the resulting ceramic tube blank during the process of filling the accommodating cavity with ceramic powder to form the ceramic tube blank. A sealant seals the bottom of the accommodating cavity to prevent the ceramic powder from leaking out.

[0029] In the forming mold provided by the present application, both the flexible sleeve and the rigid outer shell provide a connection portion with a diameter larger than the diameter of the ceramic tube, which can make the ceramic powder entering the mold at the beginning of filling evenly distributed along the circumference, avoiding the accumulation of ceramic powder at different positions when forming small-diameter ceramic tubes, thereby introducing defects such as micropores. At the same time, the ceramic tube blank obtained by homogenization filling can be evenly distributed along the axial stress. The rigid outer shell, flexible sleeve and rigid inner mold of the forming mold of the present application are coaxial, and are filled into the accommodating cavity by vibration. The ceramic powder is more uniform and dense, thereby improving the straightness and wall thickness consistency of the ceramic tube blank. After isostatic pressing, the rigid inner mold is easy to remove, and the length and outer diameter ratio of the produced ceramic tube can exceed 50, and the inner diameter can reach 3mm.

[0030] 2. In the ceramic tube isostatic pressing system of the present application, the vibration table vibrates while ceramic powder is placed into the accommodating cavity, which can reduce the gaps between the ceramic powders and increase the density of the formed ceramic tube blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Figure 1 A schematic diagram of the overall structure of an isostatic pressing mold for a ceramic tube in one embodiment of the present application is shown.

[0033] Figure 2 Show Figure 1 Enlarged view of part A.

[0034] Figure 3 A top view of a filler member of an isostatic pressing die for a ceramic tube according to an embodiment of the present application is shown.

[0035] Figure 4 Show Figure 3 Longitudinal cross-section of AA. DETAILED DESCRIPTION

[0036] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may be practiced without these specific details.

[0037] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "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 a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0038] It should also be noted that, in the description of the present application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0039] In order to solve the problems existing in the prior art, an embodiment of the present application provides a ceramic tube isostatic pressing die, such as Figure 1-4As shown, it includes a rigid shell 1 with an inner cavity and open top and bottom. The inner diameter can be 32 mm, the outer diameter can be 38 mm, and the length can be 930 mm. The material is stainless steel. A rigid inner mold 3 is disposed in the inner cavity of the rigid shell 1. The rigid inner mold 3 can be an inner steel film made of one of tungsten steel, ceramic, and a high-rigidity metal alloy. The diameter of the rigid inner mold 3 is 3 to 8 mm, preferably 7 mm, and the length can be 1000 mm. A flexible sleeve is disposed between the rigid shell 1 and the rigid inner mold 3. The flexible sleeve is made of rubber and has an outer diameter of 30-31 mm, an inner diameter of 26-28 mm, and a length of 950 mm. The flexible sleeve and the rigid inner mold 3 form a receiving cavity 4 for accommodating ceramic powder, and a sealing member 6 is used to seal the bottom of the receiving cavity 4. The sealing member 6 is made of vacuum rubber. The ceramic powder is integrally formed in the receiving cavity 4 through a cold isostatic pressing process. The formed ceramic tube can be formed into a tubular structure with a length-to-outer-diameter ratio greater than or equal to 50. Of course, tubular structures with a length-to-outer-diameter ratio less than 50 can also be produced. In practical applications, a small amount of organic binder is doped into the ceramic powder. Compared with existing technologies, the amount of doped binder is significantly reduced, resulting in a higher density ceramic tube while making it easier to control the impurity content of the ceramic tube.

[0040] In the above embodiment provided by the present application, the design of the flexible sleeve being located between the rigid outer shell 1 and the rigid inner mold 3 can play a buffering role for the ceramic powder in the process of placing the ceramic powder in the accommodating cavity 4; the use of the rigid outer shell 1 plays a supporting role for the flexible sleeve and will not cause the flexible sleeve to deform. In the process of filling the accommodating cavity 4 with ceramic powder to form a ceramic tube blank, the straightness of the final ceramic tube blank can be guaranteed. The seal 6 blocks the bottom of the accommodating cavity 4 so that the ceramic powder does not leak out. In the ceramic tube isostatic pressing mold provided by the present application, the rigid outer shell 1, the flexible sleeve and the rigid inner mold 3 are coaxial and are filled into the accommodating cavity 4 by vibration. The ceramic powder is more uniform and dense, thereby improving the straightness and wall thickness consistency of the ceramic tube blank. After isostatic pressing, the rigid inner mold 3 is easy to come out, and the ratio of the length to the outer diameter of the produced ceramic tube can exceed 50, and the inner diameter can reach 3 mm.

[0041] In a specific embodiment, the rigid shell 1 includes a shell body 11; and a shell connection portion 12 located at the bottom side of the shell body 11 and connected to the shell body 11; the radial dimension of the shell connection portion 12 is larger than the radial dimension of the shell body 11. To enable the flexible sleeve to adapt to the rigid shell 1, the flexible sleeve includes a flexible body 21; and a flexible connection portion 22 located at the bottom side of the flexible body 21 and connected to the flexible body 21; the radial dimension of the flexible connection portion 22 is larger than the radial dimension of the flexible body 21. Because the formed ceramic tube needs to be sintered, the radial dimension of the shell connection portion 12 is larger than the radial dimension of the shell body 11, and the radial dimension of the flexible connection portion 22 is larger than the radial dimension of the flexible body 21. As a result, the final ceramic tube also has a tube body and a tube body connection portion located at the bottom side of the tube body and connected to the tube body. This tube-body connection ensures uniform circumferential distribution of the ceramic powder entering the mold at the start of filling, preventing defects such as micropores caused by accumulation of ceramic powder at different locations when forming small-diameter ceramic tubes. It also ensures uniform axial stress distribution in the resulting ceramic tube blank. During sintering, the final ceramic tube can be suspended by a hanging rope at the junction between the main body and the tube-body connection, with the main body facing downward relative to the main body connection, facilitating sintering.

[0042] In one specific embodiment, the top of the flexible sleeve extends to the outside of the top of the rigid shell 1, extending 110 to 20 mm beyond the rigid shell. This allows for easy removal of the flexible sleeve from the rigid shell 1 after the ceramic tube blank is formed. The bottom of the flexible sleeve is located within the rigid shell 1, allowing the seal 6 to be flush with the bottom of the rigid shell 1, facilitating installation of the rigid shell 1 on the surface of the vibration table 5. The length of the rigid inner mold 3 is greater than that of the rigid shell 1. Furthermore, the top of the rigid inner mold 3 extends to the outside of the top of the flexible sleeve to facilitate separation of the rigid inner mold 3 from the ceramic tube after forming the ceramic tube.

[0043] In a specific example, the mold further includes a filler 7 provided with a feed hole 72, the outer diameter of which is set to be in close contact with the inner wall of the rigid shell 1 through the flexible sleeve. The material of the filler 7 is polytetrafluoroethylene. Since the flexible sleeve is very flexible, it is not convenient to directly fill the accommodating cavity 4 with ceramic powder. The use of the filler 7 can make the top of the flexible sleeve relatively fixed. In order to reduce the gaps between the ceramic powders and form a ceramic tube blank with a higher density, the entire mold is vibrated during the process of filling the accommodating cavity 4 with ceramic powder. During the vibration process, the use of the filler 7 prevents the top of the flexible sleeve from deforming, making the filling more convenient.

[0044] Furthermore, the filler member 7 includes a centrally located through-hole 71 for the rigid inner mold 3 to pass through. Surrounding the through-hole 71 are at least two through-holes 72 for feeding material. The design of the through-holes 71 secures the rigid inner mold 3, ensuring uniformity and consistency in the resulting ceramic tube blank. A partition 73 between adjacent through-holes 72 is connected to the arms of the through-holes 71, supporting the entire through-hole 71.

[0045] In one embodiment, the seal 6 is disposed at the bottom opening of the flexible sleeve; the center of the seal 6 includes a slot for inserting the rigid inner mold 3. The slot allows the rigid inner mold 3 to be fixed at the center of the flexible sleeve, further ensuring uniformity and consistency of the formed ceramic tube blank.

[0046] Another embodiment of the present application further provides a ceramic tube isostatic pressing system, comprising the ceramic tube isostatic pressing mold as described above; a vibration table 5, comprising a table surface for fixing and supporting the ceramic tube isostatic pressing mold; and an eccentric motor 92 for vibrating the vibration table 5. Specifically, the eccentric motor 92 is disposed between the base 91 and the vibration table 5, and the vibration frequency can be 50 Hz. The top of the eccentric motor 92 is connected to the bottom surface of the vibration table 5. The vibration table 5 is driven to vibrate under the action of the eccentric motor 92.

[0047] In this embodiment, the vibration table 5 is vibrated while the ceramic powder is put into the accommodating cavity 4 , which can reduce the gaps between the ceramic powders and increase the density of the formed ceramic tube blank.

[0048] In one embodiment, an extension plate 13 extends outward from the bottom edge of the rigid housing 1. The extension plate 13 is fixedly connected to the vibration table 5 via a fixing member 14. Specifically, the fixing member 14 passes through the extension plate 13 and the vibration table 5 to connect the two to form a single unit. This allows the vibration table 5 to vibrate the ceramic powder in the accommodating cavity 4, resulting in a more uniform and dense ceramic tube blank. The fixing member 14 may be a bolt.

[0049] In one embodiment, the molding system further includes a base 91 connected to the vibration table 5 via an elastic member 8. The base 91 allows the entire molding system to be placed on the ground. The use of the elastic member 8 can increase the vibration frequency of the vibration table 5. The elastic member 8 can be a spring.

[0050] Another embodiment of the present application further provides a method for forming a ceramic tube, comprising:

[0051] Step S1: Use a seal 6 to seal the bottom of the accommodating cavity 4 of the flexible sleeve, insert the rigid inner mold 3 into the seal 6, and obtain an inner mold assembly; the rigid inner mold 3 is located at the center of the flexible sleeve;

[0052] Step S2: insert the inner mold assembly into the inner cavity of the rigid outer shell 1, with the top of the rigid inner mold 3 exceeding the top of the rigid outer shell 1; use a seal 6 to seal the bottom of the accommodating cavity 4 of the flexible sleeve, insert the rigid inner mold 3 into the seal 6, and install a filler 7 between the rigid inner membrane 3 and the top of the flexible sleeve to obtain the inner mold assembly.

[0053] Step S3: fix the rigid shell 1 on the table surface of the vibration table 5. The vibration table 5 vibrates under the action of the eccentric motor 92. While the vibration table 5 vibrates, ceramic powder is filled into the accommodating cavity formed between the flexible sleeve 3 and the rigid inner mold 3 to form a ceramic tube blank.

[0054] During specific use, the isostatic pressing mold for the ceramic tube is first installed on the vibration table 5. Then, while the vibration table 5 is vibrating, ceramic powder is placed in the accommodating cavity 4 formed between the flexible sleeve and the rigid inner mold 3. When the ceramic powder fills the entire accommodating cavity 4, the vibration table 5 stops vibrating; the filler 7 is replaced with the sealing member 6, and the inner mold assembly is then pulled out from the bottom of the rigid shell 1, and then inserted into the inner cavity of the rigid shell 1 from the top of the rigid shell 1. At this time, the portion of the rigid inner mold 3 that exceeds the flexible outer sleeve is located in the inner cavity of the connection portion 12 of the rigid shell 1, and the portion of the flexible sleeve with a larger diameter at the connection portion is located on the outside of the top of the rigid shell 1. After installation is completed, the vibration table 5 is continued to vibrate, and finally a ceramic tube blank is formed. This ensures that the density of the formed ceramic tube blank is more uniform in the longitudinal direction, while further improving the wall thickness consistency of the ceramic tube. It should be noted that since the ceramic powder is in a vibrating state during the process of placing it into the accommodating cavity 4, the ceramic powder at the connection portion 12 is relatively dense and hard at this time, so it will not loosen even if it is located on the outside of the top of the rigid shell 1.

[0055] Step S4, take out the inner mold assembly and the ceramic tube blank, and place them in a cold isostatic press to form the ceramic tube blank into a ceramic tube. Specifically, after forming, the flexible sleeve, the rigid inner mold 3 and the ceramic tube blank are taken out, and then the PVC sleeve is put on the flexible sleeve and placed in a cold isostatic press to form the ceramic tube. The pressure of the cold isostatic press can be 150MPa, and the pressure is maintained for 5 minutes. After forming, the rigid inner mold 3, the flexible sleeve and the formed ceramic tube are separated, and then sintered. After sintering is completed, the main body of the ceramic tube and the tube connection part are separated, and finally the main body of the ceramic tube is formed. The aperture of the main body of the ceramic tube is 5 to 7mm. Here, when the ceramic tube blank is cold isostatically pressed in the cold isostatic press, the flexible sleeve can ensure that the rigid inner mold 3 is in the center of the flexible outer sleeve, and the rigid inner mold 3 will not bend. The wall thickness uniformity of the ceramic tube prepared in this way is better, the inner hole of the formed ceramic tube has high straightness, and the rigid inner mold 3 will not bend and deform, which is convenient for demolding.

[0056] Isostatic pressing involves placing the sample to be pressed in a high-pressure vessel. The incompressible nature of the liquid medium and its ability to uniformly transmit pressure are utilized to uniformly pressurize the sample from all directions. As the liquid medium is pumped into the pressure vessel via a pressure pump, its pressure remains constant and is evenly transmitted in all directions, according to the principles of fluid mechanics. This results in uniform and consistent pressure on the powder in the high-pressure vessel.

[0057] In practical applications, in order to make the rigid inner mold 3 easier to remove from the formed ceramic tube, a layer of oil can be applied to the outer wall of the rigid inner mold 3 before the rigid inner mold 3 is placed in the flexible sleeve to reduce the friction between the rigid inner mold 3 and the ceramic tube after forming.

[0058] Compared with the prior art, by using the ceramic tube forming method provided in the present application, a small amount of organic binder is doped into the ceramic powder, and the purity and density of the finally prepared ceramic tube are both high, making it easy to control the impurity content of the ceramic tube product. At the same time, there are almost no pores inside the formed ceramic tube blank, which greatly improves the plasma and chemical corrosion resistance of the ceramic tube and increases the service life of the ceramic tube.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A ceramic tube isostatic pressing die, characterized in that: include a rigid housing having an interior cavity and open top and bottom; a rigid inner mold for being disposed in the inner cavity of the rigid outer shell; a flexible sleeve for being disposed between the rigid outer shell and the rigid inner mold; The flexible sleeve and the rigid inner mold may form a receiving cavity for receiving ceramic powder; as well as A sealing member is used to seal the bottom of the accommodating cavity.

2. The isostatic pressing die for ceramic tubes according to claim 1, characterized in that: The top of the flexible sleeve may extend to the outside of the top of the rigid shell; The length of the rigid inner mold is greater than the length of the rigid outer shell.

3. The isostatic pressing die for ceramic tubes according to claim 1, characterized in that: The mold further comprises a filler member provided with a material passing through hole, the outer diameter of which is set to be in close contact with the inner wall of the rigid shell through the flexible sleeve.

4. The isostatic pressing die for ceramic tubes according to claim 1, characterized in that: The sealing member comprises a slot at the center thereof for inserting the rigid inner mold.

5. The isostatic pressing die for ceramic tubes according to claim 1, characterized in that: The rigid housing includes a housing body; and a shell connecting portion located at the bottom side of the shell main body and communicating with the main body; The radial dimension of the shell connecting portion is greater than the radial dimension of the shell main body portion.

6. The isostatic pressing die for ceramic tubes according to claim 5, characterized in that: The flexible sleeve includes a flexible main body portion; and a flexible connecting portion located at the bottom side of the flexible main body and communicating with the flexible main body; The radial dimension of the flexible connection portion is greater than the radial dimension of the flexible main body portion.

7. A ceramic tube isostatic pressing system, characterized in that: include The isostatic pressing die for ceramic tubes according to any one of claims 1 to 6; a vibration table comprising a table surface for fixing and supporting the isostatic pressing mold for the ceramic tube; as well as An eccentric motor for vibrating the vibration table.

8. The ceramic tube isostatic pressing system according to claim 7, characterized in that: The bottom edge of the rigid shell extends outward to form an extension plate; The extension plate may be fixedly connected to the vibration table via a fixing member.

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