Isostatic pressing one-time forming die and method for ceramic tube shell with inner table

Abstract

The invention discloses an isostatic pressing one-time forming die and method for a ceramic tube shell with an inner table, and belongs to the technical field of ceramic material forming. The mold comprises a cylindrical elastic mold sleeve and a rigid mold core which are concentrically arranged in a sleeved mode, and the space between the cylindrical elastic mold sleeve and the rigid mold core is used for being filled with ceramic tube shell raw materials with an inner table. The rigid mold core comprises a rigid upper mold core and a rigid lower mold core which are connected in a matched manner, and a sealing device is arranged on a connecting surface; an elastic cover plate which is arranged in the cylindrical elastic die sleeve in a sleeving manner and is in interference fit with the cylindrical elastic die sleeve is arranged on the top surface of the rigid upper die core; a base is arranged at the lower end of the rigid lower die core, and the outer diameter of the base, the inner diameter of the cylindrical elastic die sleeve and the outer diameter of the elastic cover plate are the same. According to the invention, one-time compression molding of the isostatic pressing blank of the ceramic tube shell with the inner table is realized, and a traditional secondary turning blank molding process mode is replaced. The machining efficiency and the machining quality stability of the blank are improved, meanwhile, the blank pressing material is reduced, and the blank density at the step is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic material forming, and relates to an isostatic pressing one-time forming die and method for a ceramic tube shell with an inner platform. Background Art

[0002] The vacuum interrupter is the core component of medium and high voltage power switches, and is widely used in industries such as power, switches, high voltage power transmission and transformation due to its excellent electrical, thermal and mechanical properties. Its alumina ceramic tube shell is one of the key parts of the vacuum interrupter. Isostatic pressing technology is an advanced technology that uses the products in a sealed high-pressure container to be formed under the state of equal high pressure in all directions. Compared with unidirectional or bidirectional pressing forming, isostatic pressing forming has the advantages of uniform density and good airtightness.

[0003] However, at present, it is difficult to directly press and form the ceramic shell with an inner platform by a traditional isostatic pressing die, and an inner platform needs to be formed through subsequent machining (secondary turning and grinding). This inner platform processing and forming method is easy to cause damage to the tube shell and reduce the surface finish of the inner part during the production process. Moreover, the working effect is low, raw materials are wasted, and the production cost is increased. In the existing production technology using an inner platform forming die, due to the complex matching structure of the die design and the large weight, the operation convenience is poor in the actual production process, resulting in poor promotion and application effects. At the same time, after the pressure is released and the pressing is completed, the blank expands radially outwards, and the friction between the step plane position and the die is easy to cause the problem of force deficiency. The Chinese invention patent "An Isostatic Pressing Die for a Straight Step Ceramic Shell" with the authorization announcement number CN 109435022 B discloses an isostatic pressing die for a straight step ceramic shell. The die structure includes an upper die core, a lower die core and a pull rod. A first annular groove is provided beside the central hole of the upper die core, and a first expansion ring is arranged in the first annular groove. One surface of the first expansion ring is in contact with the surface of the lower die core. A second expansion ring is arranged between the second step part and the third step part. The die structure disclosed in the die structure is to separate the die by the elastic expansion ring between the dies during pressure relief to reduce the problem of force friction confirmation at the step. However, this structure cannot avoid the stress damage problem caused by the radial plane wear of the die and the blank expansion force before the die is disassembled. Summary of the Invention

[0004] The purpose of the invention is to solve the technical problems of complex die structure, inconvenient operation and step force damage after die disassembly during the one-time pressing of the alumina ceramic shell in the prior art, and provide an isostatic pressing one-time forming die and method for a ceramic tube shell with an inner platform.

[0005] In order to achieve the above purpose, the invention adopts the following technical solutions: In a first aspect, the present invention discloses an isostatic pressing one-time forming die for an inner-platform ceramic tube shell, which includes a cylindrical elastic die sleeve and a rigid die core coaxially arranged. The raw material for the inner-platform ceramic tube shell is filled between the cylindrical elastic die sleeve and the rigid die core. The rigid die core includes a rigid upper die core and a rigid lower die core that are fitted and connected, and a sealing device is arranged on the connecting surface. The top surface of the rigid upper die core is provided with an elastic cover plate that is sleeved in the cylindrical elastic die sleeve and is in interference connection with it. A base is arranged at the lower end of the rigid lower die core, and the outer diameter of the base, the inner diameter of the cylindrical elastic die sleeve, and the outer diameter of the elastic cover plate are the same.

[0006] Further improvements are as follows: Both the rigid upper die core and the rigid lower die core are provided with weight-reducing inner holes, and inserts are arranged in the weight-reducing inner holes.

[0007] The wall thickness at the weight-reducing inner holes of the rigid upper die core and the rigid lower die core is 5.5 mm - 7 mm.

[0008] A lower die core elastic sealing layer is also arranged between the weight-reducing inner hole of the rigid lower die core and the insert arranged therein.

[0009] A conical boss is arranged at one end of the rigid upper die core where it is fitted and connected to the rigid lower die core, and a conical concave hole is arranged at the corresponding position of the rigid lower die core. The rigid upper die core and the rigid lower die core form an inclined cone positioning fit.

[0010] The fitting depth of the inclined cone positioning fit is 18 mm - 22 mm, and the inclined cone angle is 2° - 5°.

[0011] The rigid upper die core and the rigid lower die core are made of 40Cr die steel, with a hard chromium plating coating on the surface, the surface roughness is less than or equal to Rac0.04, and the hardness is 40 - 50 degrees on the Shore hardness scale; the cylindrical elastic die sleeve is made of rubber or polyurethane material, with a Shore hardness of 50 - 60 degrees and a thickness of 11 mm - 13 mm.

[0012] A draft angle of 2° - 3° is arranged on the contact surfaces of the bottom surface of the rigid lower die core and the base with the raw material of the inner-platform ceramic tube shell.

[0013] A clamp or an elastic rubber ring is arranged at the outer wall of the upper end of the cylindrical elastic die sleeve corresponding to the elastic cover plate; a clamp or an elastic rubber ring is arranged at the outer wall of the lower end of the cylindrical elastic die sleeve corresponding to the base.

[0014] In a second aspect, the present invention discloses an isostatic pressing one-time forming method for an inner-platform ceramic tube shell using the above isostatic pressing one-time forming die, which includes the following steps: Step 1: Apply sealing oil on the mating surfaces of the rigid upper die core and the rigid lower die core to form a suction connection, and brush release agent on the contact surface between the base and the raw material of the ceramic tube shell with an inner platform; install the rigid upper die core and the rigid lower die core into a cylindrical elastic die sleeve, and install a clamp or an elastic rubber ring at the outer wall of the lower end of the cylindrical elastic die sleeve corresponding to the base to obtain an initial isostatic pressing primary forming die. Step 2: Pour the raw material of the ceramic tube shell with an inner platform into the initial isostatic pressing primary forming die, and place the initial isostatic pressing primary forming die on a vibration platform to compact the raw material of the ceramic tube shell with an inner platform inside it. Step 3: Install an elastic cover plate at the upper end of the initial isostatic pressing primary forming die, and install a clamp or an elastic rubber ring at the outer wall of the upper end of the cylindrical elastic die sleeve corresponding to the elastic cover plate to obtain a sealed isostatic pressing primary forming die. Step 4: Place the isostatic pressing primary forming die into an isostatic press for isostatic pressing; the pre-pressurization pressure of the isostatic press is 5 - 10 MPa, the pressure increase adopts a linear pressure increase, and the pressure increase rate is about 10 - 20 Mpa / min; the isostatic pressing forming holding pressure is 100 - 150 Mpa, and the holding time is about 100 - 150 s; the isostatic pressure relief adopts a stepped pressure relief method, and the pressure relief rate is 5 - 15 Mpa / min. The first pressure relief is to 100 MPa and hold for 20 s, and the second pressure relief is to 20 Mpa and hold for 10 s. Step 5: After the isostatic pressing is completed, remove the isostatic pressing primary forming die. After removing the elastic cover plate at the upper end of the cylindrical elastic die sleeve, place the isostatic pressing primary forming die in the reverse direction, invert and eject the blank and the rigid upper die core, and take out the blank.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses an isostatic pressing primary forming die for a ceramic tube shell with an inner platform. The isostatic pressing primary forming die of the present invention includes a rigid upper and lower die core, a cylindrical elastic die sleeve and an elastic cover plate. The isostatic pressing blank of the ceramic tube shell with an inner platform is formed in one pressing by adopting an upper and lower die sealing method, replacing the traditional process method of forming the blank by secondary turning. The processing efficiency and the stability of the processing quality of the blank are improved. At the same time, the material used for pressing the blank is reduced, and the density of the blank body at the step is ensured.

[0016] Furthermore, a sealing oil seal matching method is adopted between the parting surfaces of the rigid upper and lower die cores, simplifying the matching method of the forming die. At the same time, 2° - 5° draft cones are designed on both the step plane and the bottom surface of the rigid lower die core of the forming die. Combined with the release agent, when the isostatic pressing is formed and the pressure is relieved, it avoids the friction force between the step plane and the forming die during the expansion and outward expansion of the blank, ensures the uniform stress of the pressing at the step, reduces the influence of the internal stress of the step, and improves the processing quality of the isostatic pressing primary forming blank.

[0017] Furthermore, the rigid upper and lower die cores adopt a hollowed-out weight reduction design, and pads are inlaid inside, such as inserts made of nylon material. On the premise of ensuring the balance and sealing of the pressure-bearing strength of the die under pressure, the weight is reduced by more than about 50% compared with the traditional die, which greatly reduces the operating labor intensity of the isostatic pressing forming die.

[0018] The present invention discloses an isostatic pressing one-time forming method for a ceramic tube shell with an inner platform. The pressure relief mode of isostatic pressing forming adopts multi-step segmented pressure relief to slow down the problem of uneven local stress caused by the too rapid release of internal stress during the pressure relief expansion of the blank. The segmented slow pressure relief enables the internal expansion of the blank to be released one by one. At the same time, in cooperation with the draft taper design of the isostatic pressing die core, the densification of the stepped machining and the uniform stress are ensured. In addition, the rigid die core and the elastic die sleeve cooperate with each other, and in combination with the sealing oil and the clamp seal, effectively prevent the leakage of high-pressure medium and ensure the accurate transmission of the forming pressure; the combination of vibration pretreatment and staged isostatic pressing process makes the raw materials uniformly densified, the density deviation of the product is <1%, and the inner platform structure accuracy reaches ±0.05 mm; the stepped pressure relief strategy (100 MPa → 20 MPa) combined with the reverse demolding technology significantly reduces the residual stress, and the finished product rate is increased to more than 98%; the detachable design of the die and the application of the mold release agent simplify the demolding process, shorten the single forming cycle by 30%, the die can be reused, and the comprehensive production cost is reduced. This method provides an efficient solution for the near-net forming of complex structure ceramic components. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a structural diagram of an isostatic pressing one-time forming die for a ceramic tube shell with an inner platform in an embodiment of the present invention.

[0021] Wherein: 1 - rigid upper die core; 101 - upper die core insert; 2 - rigid lower die core; 201 - lower die core elastic sealing layer; 202 - lower die core insert; 3 - cylindrical elastic die sleeve; 4 - elastic rubber cover plate. Detailed Embodiments

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships in which the inventive product is customarily placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0027] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0028] The following further describes the present invention in detail with reference to the accompanying drawings: See Figure 1, an embodiment of the present invention discloses an isostatic pressing one-time forming die with an inner table ceramic shell, which is characterized in that it includes a cylindrical elastic die sleeve 3 and a rigid die core coaxially arranged. The raw material of the inner table ceramic shell is filled between the cylindrical elastic die sleeve 3 and the rigid die core; the cylindrical elastic die sleeve 3 is made of rubber or polyurethane, with a Shore hardness of 50-60 degrees and a thickness of 11 mm-13 mm. The rigid die core includes a rigid upper die core 1 and a rigid lower die core 2 that are fitted and connected, and a sealing device is arranged on the connecting surface. The sealing device is sealing oil, and the sealing oil is used in the parting surface between the rigid upper and lower die cores, which simplifies the matching method of the forming die; both the rigid upper die core 1 and the rigid lower die core 2 are provided with weight-reducing inner holes, and inserts are arranged in the weight-reducing inner holes. The inserts are made of nylon. The rigid upper and lower die cores adopt a hollowed-out weight-reducing design, and pads are inlaid inside, such as inserts made of nylon. On the premise of the balance and sealing performance of the pressure-bearing strength of the die, the weight is reduced by more than about 50% compared with the traditional die, which greatly reduces the operation labor intensity of the isostatic pressing forming die. The wall thickness at the weight-reducing inner holes of the rigid upper die core 1 and the rigid lower die core 2 is 5.5 mm-7 mm. A lower die core elastic sealing layer 201 is also arranged between the weight-reducing inner hole of the rigid lower die core 2 and the insert arranged therein. The top surface of the rigid upper die core 1 is provided with an elastic cover plate 4 that is sleeved in the cylindrical elastic die sleeve 3 and is in interference connection with it; a base is arranged at the lower end of the rigid lower die core 2, and the outer diameter of the base, the inner diameter of the cylindrical elastic die sleeve 3, and the outer diameter of the elastic cover plate 4 are the same. A conical boss is arranged at one end of the rigid upper die core 1 where it is fitted and connected with the rigid lower die core 2, and a conical concave hole is arranged at the corresponding position of the rigid lower die core 2. The rigid upper die core 1 and the rigid lower die core 2 form an inclined cone positioning fit. The fitting depth of the inclined cone positioning fit is 18 mm-22 mm, and the inclined cone angle is 2°-5°. The rigid upper die core 1 and the rigid lower die core 2 are made of 40Cr die steel, with a hard chromium plating layer on the surface, the surface roughness is less than or equal to Rac0.04, and the hardness is Shore hardness 40-50 degrees; a draft angle of 2°-3° is arranged on the bottom surface of the rigid lower die core 2 and the contact surface between the base and the raw material of the inner table ceramic shell. At the same time, a draft cone of 2°-5° is designed on the step plane and the bottom surface of the rigid lower die core of the forming die. In combination with the release agent, when the pressure is released during isostatic pressing forming, it avoids the friction force between the step plane and the forming die during the expansion of the blank, ensures the uniform stress of the step during pressing, reduces the influence of internal stress at the step, and improves the processing quality of the isostatic pressing one-time forming blank. A clamp or an elastic rubber ring is arranged at the upper end of the cylindrical elastic die sleeve 3 at the outer wall corresponding to the elastic cover plate 4; a clamp or an elastic rubber ring is arranged at the lower end of the cylindrical elastic die sleeve 3 at the outer wall corresponding to the base.

[0029] The present invention discloses an isostatic pressing one - time forming die for a ceramic tube shell with an inner platform. The isostatic pressing one - time forming die of the present invention includes a rigid upper and lower die core, a cylindrical elastic die sleeve, and an elastic cover plate. The upper and lower die sealing method is adopted to realize the one - time isostatic pressing forming of the isostatic pressing blank of the ceramic tube shell with an inner platform, replacing the traditional process method of forming the blank by secondary turning. It improves the processing efficiency and the stability of processing quality of the blank, reduces the material used for blank pressing, and ensures the density of the blank at the step.

[0030] The embodiment of the present invention also discloses an isostatic pressing one - time forming method for a ceramic tube shell with an inner platform using the above - mentioned isostatic pressing one - time forming die, which includes the following steps: Step 1: Apply sealing oil on the mating surfaces of the rigid upper die core 1 and the rigid lower die core 2 to form a suction connection, and brush release agent on the contact surface between the base and the raw material of the ceramic tube shell with an inner platform; Install the rigid upper die core 1 and the rigid lower die core 2 into the cylindrical elastic die sleeve 3, and install a clamp or an elastic rubber ring at the outer wall corresponding to the base at the lower end of the cylindrical elastic die sleeve 3 to obtain an initial isostatic pressing one - time forming die; Step 2: Pour the raw material of the ceramic tube shell with an inner platform into the initial isostatic pressing one - time forming die, and place the initial isostatic pressing one - time forming die on a vibration platform to vibrate and compact the raw material of the ceramic tube shell with an inner platform inside; Step 3: Install the elastic cover plate 4 at the upper end of the initial isostatic pressing one - time forming die, and install a clamp or an elastic rubber ring at the outer wall corresponding to the elastic cover plate 4 at the upper end of the cylindrical elastic die sleeve 3 to obtain a sealed isostatic pressing one - time forming die; Step 4: Place the isostatic pressing one - time forming die into an isostatic press for isostatic pressing; The pre - pressing pressure of the isostatic press is 5 - 10 MPa, the pressure rise adopts linear pressure rise, and the pressure rise rate is about 10 - 20 Mpa / min; The isostatic pressing forming holding pressure is 100 - 150 Mpa, and the holding time is about 100 - 150 s; The isostatic pressure relief adopts a stepped pressure relief method, and the pressure relief rate is 5 - 15 Mpa / min. The first pressure relief is to 100 MPa and hold for 20 s, and the second pressure relief is to 20 Mpa and hold for 10 s; Step 5: After the isostatic pressing is completed, remove the isostatic pressing one - time forming die. After removing the elastic cover plate 4 at the upper end of the cylindrical elastic die sleeve 3, place the isostatic pressing one - time forming die in the reverse direction, invert and eject the blank and the rigid upper die core, and take out the blank.

[0031] The present invention discloses a one-step isostatic pressing method for a ceramic tube shell with an inner platform. The isostatic pressing pressure relief method adopts multi-step segmented pressure relief to alleviate the problem of local stress inconsistency caused by the excessively rapid release of internal stress during the pressure relief and expansion process of the blank. The segmented slow pressure relief realizes the release of the internal expansion of the blank one by one, and at the same time, the draft taper design of the isostatic pressing die core ensures the density of the step processing and the uniformity of force. In addition, the rigid die core and the elastic die sleeve work together, and the sealing oil and clamp seals effectively prevent the leakage of high-pressure media and ensure the precise transmission of the forming pressure; the vibration pretreatment is combined with the staged isostatic pressing process to make the raw material uniformly densified, the product density deviation is <1%, and the inner platform structure accuracy reaches ±0.05mm; the stepped pressure relief strategy (100MPa→20MPa) is combined with the reverse demolding technology to significantly reduce the residual stress and increase the yield rate to more than 98%; the detachable mold design and the application of the demolding agent simplify the demolding process, shorten the single molding cycle by 30%, and the mold can be reused, thereby reducing the overall production cost. This method provides an efficient solution for the near-net-shape forming of complex structural ceramic components.

[0032] The working principle of the present invention is as follows: An isostatic pressing one-time forming die and method with an inner platform ceramic shell, including a cylindrical elastic die sleeve 3 and a cylindrical rigid die core located inside the cylindrical elastic die sleeve 3. The die core includes an elastic rubber cover plate 4, a rigid upper die core 1, and a rigid lower die core 2 that are concentrically arranged from top to bottom. The elastic rubber cover plate 4 is attached to the top of the rigid upper die core 1. The bottom of the rigid upper die core 1 is designed with a tapered boss, and the tapered groove at the top of the rigid lower die core 2 is fixed by tapered surface fit. A sealing oil is applied between the parting surface of the rigid upper die core 1 and the parting surface of the rigid lower die core 2 to achieve suction connection. The rigid upper die core 1 and the rigid lower die core 2 are made of die steel and 40Cr material, and the surface of the die is electroplated with a hard chromium coating. The surface roughness of the die is about Rac0.04. The hardness of the die is 40-50 degrees on the Shore hardness scale. The middle of the rigid upper die core is hollowed out to reduce the weight of the die, and the wall thickness of the die on one side is about 5.5-7mm. The rigid upper die core 1 is provided with a die top surface, a mating parting surface, and a tapered boss ground surface from top to bottom. A nylon insert block 101 of the upper die core is embedded in the hollow position of the rigid upper die core 1 to fill the hollow position of the upper die core. The upper end surface of the nylon insert block 101 of the upper die core is flush with the rigid upper die core 1. A tapered boss is designed on the parting surface of the rigid upper die core, and a tapered mating concave hole is provided on the parting surface of the rigid lower die core. The tapered boss of the rigid upper die core is in oblique cone positioning fit with the tapered concave hole of the rigid lower die core. The mating depth of the oblique cone hole pin is about 20mm, and the oblique cone angle is 2°-5°. The rigid lower die core 2 is provided with a mating parting surface, an inner platform plane, a lower die bottom surface, and a die sleeve positioning end surface. The inner platform plane of the rigid lower die core is concentric and parallel to the lower die bottom surface. The inner platform plane and the lower die bottom surface of the rigid lower die core 2 are designed with a draft angle of about 2°, and there is no friction force on the blank plane when the blank is depressurized and expanded. A weight-reducing inner hole is provided inside the rigid lower die core 2, and the wall thickness of the die is about 5.5-7mm. The weight-reducing inner hole of the rigid lower die core is filled with an elastic sealing layer and a nylon spacer from top to bottom in sequence, and the three are closely fitted. The cylindrical elastic die sleeve is made of rubber or polyurethane material, and the designed Shore hardness of the die sleeve is 50-60 degrees, and the thickness of the die sleeve is about 12mm. The rigid lower die core 2 is provided with a base, and the outer diameter of the base is the same as the inner diameter of the elastic die sleeve, and the outer diameter of the base is the same as the outer diameter of the elastic cover plate. The cylindrical elastic die sleeve is fitted on the base of the rigid lower die core, and one end surface of the elastic die sleeve is fitted with the die sleeve positioning surface of the rigid lower die core to maintain concentricity. A clamp or an elastic rubber ring is also provided outside the cylindrical elastic die sleeve 3. After the clamp or the elastic rubber ring is sleeved on the bottom of the elastic die sleeve 3 and tightened, the elastic die sleeve 3 and the rigid lower die core 2 are kept concentric. The elastic cover plate 4 is made of rubber or polyurethane material, the designed Shore hardness of the elastic cover plate is 20-40 degrees, the thickness is about 30mm, and the outer diameter of the cover plate has an interference fit with the inner diameter surface at the upper end of the cylindrical elastic die sleeve. A clamp or an elastic rubber ring is provided at the upper end of the outer diameter of the elastic die sleeve 3. After the clamp or the elastic rubber ring is sleeved on the upper end of the elastic die sleeve and tightened, the internal seal of the isostatic pressing forming die is maintained.

[0033] The present invention also provides an isostatic pressing one - time forming method for an inner - platform ceramic shell, which is carried out by using the isostatic pressing forming die for the inner - platform ceramic shell as described above in the present invention, and includes the following processes: Before cold isostatic pressing forming, first apply sealing oil to connect the rigid upper and lower die cores of the isostatic pressing forming die for the inner - platform ceramic shell at the parting surface, and brush release agent at the step plane. Fill the raw materials into the isostatic pressing forming die.

[0034] Place the die on a vibrating platform to compact the raw materials in the die, fix the elastic cover plate on the top of the rigid upper die core, fix and seal it with a clamp, and then put it into an isostatic press for pressing and forming.

[0035] The pre - pressing pressure of the isostatic press is 5 - 10 MPa, the pressure increase adopts linear pressure increase, and the pressure increase rate is about 10 - 20 Mpa / min. The holding pressure of isostatic pressing forming is about 100 - 150 Mpa, and the holding time is about 100 - 150 s. The pressure relief of isostatic pressing adopts a stepped pressure relief method, and the pressure relief rate is about 5 - 15 Mpa / min. The first pressure relief is to 100 MPa and hold the pressure for 20 s, and the second pressure relief is to 20 Mpa and hold the pressure for 10 s.

[0036] After the isostatic pressing is completed, remove the die from the blank rack. After removing the clamp at the upper end of the elastic die sleeve and the elastic cover plate, place the die in the reverse direction, and inversely eject the blank and the rigid upper die core. After taking out the blank and placing it in place, reinstall and fit the rigid upper and lower dies to complete the isostatic pressing one - time forming of the inner - platform ceramic shell blank.

[0037] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An isostatic pressing one-time forming die with an inner platform ceramic shell, characterized in that, It includes a cylindrically-shaped elastic die sleeve (3) and a rigid die core that are concentrically sleeved, and the cylindrically-shaped elastic die sleeve (3) and the rigid die core are used for filling raw materials of a ceramic tube shell with an inner platform; the rigid die core includes a rigid upper die core (1) and a rigid lower die core (2) that are fitted and connected and a sealing device is arranged on the connection surface; an elastic cover plate (4) that is sleeved in the cylindrically-shaped elastic die sleeve (3) and is in interference connection with it is arranged on the top surface of the rigid upper die core (1); a base is arranged at the lower end of the rigid lower die core (2), and the outer diameter of the base, the inner diameter of the cylindrically-shaped elastic die sleeve (3), and the outer diameter of the elastic cover plate (4) are the same.

2. The isostatic pressing one-time forming die for the in-band table ceramic tube shell according to claim 1, wherein, Both the rigid upper die core (1) and the rigid lower die core (2) are provided with weight-reducing inner holes, and inserts are arranged in the weight-reducing inner holes.

3. The isostatic pressing primary forming die for the in-band ceramic tube shell according to claim 2, wherein The wall thickness at the weight-reducing inner holes of the rigid upper die core (1) and the rigid lower die core (2) is 5.5 mm - 7 mm.

4. The isostatic pressing primary forming die for the in-band table ceramic shell according to claim 2, wherein A lower die core elastic sealing layer (201) is also arranged between the weight-reducing inner hole of the rigid lower die core (2) and the insert arranged in it.

5. The isostatic pressing one-time forming die for the in-band ceramic tube shell according to claim 1, characterized in that, A conical boss is arranged at one end of the rigid upper die core (1) that is fitted and connected with the rigid lower die core (2), a conical concave hole is arranged at the relative position of the rigid lower die core (2), and the rigid upper die core (1) and the rigid lower die core (2) form an inclined cone positioning fit.

6. The isostatic pressing primary forming die for the in-band ceramic tube shell according to claim 4, characterized in that The fit depth of the inclined cone positioning fit is 18 mm - 22 mm, and the inclined cone angle is 2° - 5°.

7. The isostatic pressing primary forming die for the in-band ceramic tube shell according to claim 1, characterized in that, The rigid upper die core (1) and the rigid lower die core (2) are made of 40Cr die steel, with a hard chromium coating electroplated on the surface, the surface roughness is less than or equal to Rac0.04, and the hardness is 40 - 50 degrees on the Shore hardness scale; the cylindrically-shaped elastic die sleeve (3) is made of rubber or polyurethane material, the Shore hardness is 50 - 60 degrees, and the thickness is 11 mm - 13 mm.

8. The isostatic pressing primary forming die for the in-band table ceramic shell according to claim 1, characterized in that, A draft angle of 2° - 3° is arranged on the bottom surface of the rigid lower die core (2) and the contact surface between the base and the raw materials of the ceramic tube shell with an inner platform.

9. The isostatic pressing primary forming die for the in-band table ceramic shell according to claim 1, characterized in that, A clamp or an elastic rubber ring is arranged at the outer wall of the upper end of the cylindrically-shaped elastic die sleeve (3) corresponding to the elastic cover plate (4); a clamp or an elastic rubber ring is arranged at the outer wall of the lower end of the cylindrically-shaped elastic die sleeve (3) corresponding to the base.

10. An isostatic pressing one-time forming method for a ceramic tube shell with an inner platform using the isostatic pressing one-time forming die according to any one of claims 1-9, characterized in that, It includes the following steps: Step 1, apply sealing oil on the mating surfaces of the rigid upper die core (1) and the rigid lower die core (2) to form a suction connection, and brush release agent on the contact surface between the base and the raw materials of the ceramic tube shell with an inner platform; install the rigid upper die core (1) and the rigid lower die core (2) into the cylindrically-shaped elastic die sleeve (3), and install a clamp or an elastic rubber ring at the outer wall of the lower end of the cylindrically-shaped elastic die sleeve (3) corresponding to the base to obtain an initial isostatic pressing one-time forming die. Step 2, pour the raw materials of the ceramic tube shell with an inner platform into the initial isostatic pressing one-time forming die, and place the initial isostatic pressing one-time forming die on a vibration platform to vibrate and densify the raw materials of the ceramic tube shell with an inner platform inside it. Step 3, install the elastic cover plate (4) at the upper end of the initial isostatic pressing one-time forming die, and install a clamp or an elastic rubber ring at the outer wall of the upper end of the cylindrically-shaped elastic die sleeve (3) corresponding to the elastic cover plate (4) to obtain a sealed isostatic pressing one-time forming die. Step 4: Place the isostatic pressing primary forming die into an isostatic press for isostatic pressing. The pre-pressurization pressure of the isostatic press is 5 - 10 MPa. The pressure is increased linearly, and the pressure increase rate is about 10 - 20 Mpa / min. The pressure holding for isostatic forming is 100 - 150 Mpa, and the pressure holding time is about 100 - 150 s. The isostatic pressure relief adopts a stepped pressure relief method, and the pressure relief rate is 5 - 15 Mpa / min. It is pressure held for 20 s when the pressure is first relieved to 100 MPa, and then pressure held for 10 s when the pressure is secondarily relieved to 20 Mpa. Step 5: After the isostatic pressing is completed, remove the isostatic pressing primary forming die. After removing the elastic cover plate (4) at the upper end of the cylindrical elastic die sleeve (3), place the isostatic pressing primary forming die in the reverse direction, and inversely eject the blank and the rigid upper die core, and take out the blank.

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