Hot pressing sintering mold structure and method

Abstract

The invention provides a hot-pressing sintering mold structure and method, and belongs to the technical field of batch hot-pressing production of compact materials.The hot-pressing sintering mold structure is characterized in that a bottom pressurizing device and a top pressurizing device are close to each other to pressurize a multi-layer mold cavity assembly, multi-layer multi-cavity hot-pressing sintering is achieved, transverse and longitudinal sintering spaces in a hearth are effectively utilized, and the sintering efficiency is improved; the single-furnace loading capacity of sintered products is improved, the sintering efficiency is improved, and the sintering cost is reduced; when the bottom pressurizing device and the top pressurizing device get close to each other, green bodies in the mold cavity assemblies are pressed through pressure transmission among all the layers of mold cavity assemblies, products which reach the compression design height firstly are not continuously compressed any more, and products which do not reach the compression design height are continuously compressed in the pressure transmission process; therefore, all layers of green bodies can be compressed to the designed height, the consistency of the height and density of sintered products in the same batch is improved, and the size and density yield of the sintered products in the single batch are improved on the basis of improving the yield of the sintered products in the single batch.

Description

Technical Field

[0001] The present application belongs to the technical field of batch hot pressing production of dense materials, and specifically relates to a hot pressing sintering mold structure and method. Background Art

[0002] Hot pressing sintering is a process in which a certain external force is applied simultaneously during the sintering process, causing the green material contained in the hot pressing mold to accelerate flow, rearrangement and densification under the dual effects of temperature and pressure. Compared with conventional pressureless sintering, hot pressing sintered products have high density, low sintering temperature, difficult grain growth, and strong mechanical properties. It is mainly used for sintering materials that are difficult to densify by conventional pressureless sintering, such as high-temperature ceramics, refractory metals and other high-performance materials.

[0003] Different from conventional pressureless sintering, hot pressing sintering materials must be loaded inside the hot pressing sintering mold. The diameter of the hot pressing sintered product can be accurately controlled by the inner diameter of the mold cavity. In combination with the green body weight control, the product height and density can be adjusted through the sintering process parameters (temperature / time / pressure). Due to the specific structure of the furnace body, the temperature uniformity during sintering in the hot pressing sintering furnace is not good. Sintering is generally carried out within a relatively small uniform temperature zone, resulting in a small loading capacity of sintered products in a single furnace, high production costs, low efficiency, and low accuracy in controlling the height and density of the products. Although production capacity can be increased by cutting and processing large-sized products after sintering, the processing cost of such materials is high, and in some cases they are not suitable for processing, affecting the quality of the finished product. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] In view of this, according to a first aspect of an embodiment of the present application, a hot pressing and sintering mold structure is proposed, comprising:

[0006] Bottom pressure device;

[0007] M cavity assemblies are stacked on the bottom pressure device along the height direction of the bottom pressure device, M ≥ 1;

[0008] The mold cavity assembly includes a mold cavity pad and a mold cavity plate. The mold cavity plate is arranged on the mold cavity pad. The mold cavity plate is provided with N mold cavities for placing green blanks, where N is greater than or equal to 2.

[0009] A top pressurizing device, the top pressurizing device is arranged above the mold cavity assembly located at the top layer, and the bottom pressurizing device and the top pressurizing device are used to pressurize the mold cavity assembly;

[0010] The top pressurizing device includes P first pressing heads, where P=N. The first pressing heads correspond to the mold cavities one by one, and the shapes of the first pressing heads are adapted to the shapes of the corresponding mold cavities.

[0011] In a feasible embodiment, there are N mold cavities on each layer of mold cavity plate, each mold cavity is vertically aligned with the mold cavity at the corresponding position on the mold cavity plate of the upper layer, and each mold cavity is vertically aligned with the mold cavity at the corresponding position on the mold cavity plate of the next layer to reduce the pressure difference on both sides of the mold cavity pad.

[0012] In a feasible embodiment, the hot pressing and sintering mold structure further includes:

[0013] A first cushion block is arranged in the mold cavity, and the first cushion block, the first pressing head and the mold cavity correspond one to one;

[0014] The side wall of the first cushion block is in contact with the mold cavity plate, the bottom surface of the first cushion block is in contact with the top surface of the mold cavity plate, and the green body is placed on the first cushion block.

[0015] In a feasible embodiment, the hot pressing and sintering mold structure further includes:

[0016] A second pressing head assembly is provided on the bottom surface of the cavity plate between two adjacent layers of cavity plates. The second pressing head assembly includes Q second pressing heads, where Q=P. The second pressing heads correspond one to one with the cavities on the cavity plate of the next layer. The second pressing heads are used to pressurize the green body in the cavity plate of the next layer.

[0017] A second cushion block is arranged in the mold cavity, and the second cushion block, the second pressing head and the mold cavity correspond one to one;

[0018] The side wall of the second cushion block is in contact with the mold cavity plate, the bottom surface of the second cushion block is in contact with the top surface of the mold cavity plate, and the green body is placed on the second cushion block.

[0019] In a feasible embodiment, the hot pressing and sintering mold structure further includes:

[0020] An isolation layer is provided on the outside of the green body, the isolation layer separates the green body from the first pressing head, the isolation layer separates the green body from the first cushion block, and the isolation layer separates the green body from the mold cavity plate;

[0021] Alternatively, the isolation layer separates the green body from the second pressing head, the isolation layer separates the green body from the second spacer, and the isolation layer separates the green body from the cavity plate;

[0022] In one possible embodiment, the isolation layer is a graphite paper layer or a release agent coating.

[0023] In a feasible embodiment, the hot pressing and sintering mold structure further includes:

[0024] The top pressure device includes:

[0025] A first pressurizing column, the first pressurizing column is provided on a pressurizing device, and the pressurizing device drives the first pressurizing column to move;

[0026] The first pressing plate is arranged perpendicular to the first pressurizing column, a first side of the first pressing plate is connected to the first pressurizing column, and the first pressure head is arranged perpendicularly on the second side of the first pressing plate.

[0027] In a feasible embodiment, the bottom pressurizing device includes:

[0028] A second pressurizing column, the second pressurizing column is arranged on a pressurizing device, and the pressurizing device drives the second pressurizing column to move;

[0029] The second pressure plate is arranged perpendicular to the second pressure column, the first side of the second pressure plate is connected to the second pressure column, the second side of the second pressure plate is in contact with the bottom cavity pad, and the second pressure plate and the top pressure device pressurize the cavity assembly on both sides of the cavity assembly respectively.

[0030] According to a second aspect of an embodiment of the present application, a hot pressing and sintering method is provided, which is applied to a hot pressing and sintering mold structure as in any of the above technical solutions, comprising:

[0031] Design the number of layers of the mold cavity components, assemble the green body into the corresponding mold cavity, and then load the furnace;

[0032] Calculating the total compression required for the green body in all layers of the mold cavity components, driving the top press device and / or the bottom press device to move, and pressurizing and sintering the mold cavity components until the sum of the displacements of the top press device and / or the bottom press device approaches the difference between the total compression and the mold expansion;

[0033] The hot pressing sintering is continued until the displacement of the top pressure device and / or the bottom pressure device remains substantially unchanged, so that the green bodies in all the cavity components are shrunk to the designed height, and the sintering process is completed.

[0034] Compared with the prior art, the hot pressing sintering mold structure and method of the present application have the following beneficial effects:

[0035] The hot pressing sintering mold structure provided in the embodiment of the present application includes a bottom pressurizing device, a mold cavity assembly and a top pressurizing device. By arranging a multi-layer mold cavity assembly between the bottom pressurizing device and the top pressurizing device, and arranging multiple mold cavities on each layer of the mold cavity assembly, the first pressure head corresponds to the mold cavity one by one, and the bottom pressurizing device and the top pressurizing device are brought close to each other to pressurize the multi-layer mold cavity assembly, thereby realizing multi-layer multi-cavity hot pressing sintering, effectively utilizing the horizontal and vertical sintering space in the furnace, increasing the single furnace loading capacity of sintered products, improving sintering efficiency, and reducing sintering costs; the top pressurizing device It acts directly on the topmost cavity assembly. When the bottom pressure device and the top pressure device approach each other, the green compacts in the cavity assembly are compressed by the pressure transfer between the cavity assemblies of each layer. The products that reach the compression design height first are no longer compressed, while the products that have not reached the compression design height are continuously compressed during the pressure transfer process, so that each layer of green compacts can be compressed to the design height, thereby improving the consistency of the height and density of the same batch of sintered products, and improving the size and density yield of the single batch of sintered products on the basis of increasing the output of the single batch of sintered products. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 A schematic structural diagram of a hot pressing and sintering mold structure according to an embodiment of the present application from a first angle;

[0038] Figure 2 A schematic structural diagram of a hot pressing and sintering mold structure according to an embodiment of the present application from a second angle;

[0039] Figure 3 A first schematic structural diagram of a cavity plate of a hot pressing and sintering mold structure according to an embodiment of the present application;

[0040] Figure 4 A second schematic structural diagram of a cavity plate of a hot pressing and sintering mold structure according to an embodiment of the present application;

[0041] Figure 5 A schematic flowchart of the hot pressing sintering method according to an embodiment of the present invention;

[0042] in, Figures 1 to 4 The corresponding relationship between the reference numerals and component names is as follows:

[0043] 11. Bottom pressure device; 12. Cavity assembly; 13. Top pressure device; 14. First cushion block; 15. Second pressure head; 16. Green mold; 17. Second cushion block;

[0044] 111. Second pressure column; 112. Second pressure plate;

[0045] 121. Cavity backing plate; 122. Cavity plate; 123. Cavity;

[0046] 131. First pressure column; 132. First pressure plate; 133. First pressure head. DETAILED DESCRIPTION

[0047] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to 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 should not be understood as a limitation on this application.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0049] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0050] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0051] like Figure 1 and Figure 2As shown, according to the first aspect of the embodiment of the present application, a hot pressing sintering mold structure is proposed, including: a bottom pressurizing device 11, a cavity assembly 12 and a top pressurizing device 13; M cavity assemblies 12 are stacked on the bottom pressurizing device 11 along the height direction of the bottom pressurizing device 11, M≥1; the cavity assembly 12 includes a cavity pad 121 and a cavity plate 122, the cavity plate 122 is arranged on the cavity pad 121, and N cavities 123 are arranged on the cavity plate 122, and the cavity 123 is used to place the green body 16, N≥2; the top pressurizing device 13 is arranged above the cavity assembly 12 located at the top layer, and the bottom pressurizing device 11 and the top pressurizing device 13 are used to pressurize the cavity assembly 12; the top pressurizing device 13 includes P first pressing heads 133, P=N, the first pressing heads 133 correspond one-to-one to the cavity 123, and the shape of the first pressing heads 133 is adapted to the shape of the corresponding cavity 123.

[0052] The hot pressing sintering mold structure provided in the embodiment of the present application includes a bottom pressurizing device 11, a cavity assembly 12 and a top pressurizing device 13. By arranging a multi-layer cavity assembly 12 between the bottom pressurizing device 11 and the top pressurizing device 13, and arranging a plurality of cavities 123 on each layer of the cavity assembly 12, the first pressure head 133 corresponds to the cavity 123 one by one, and the bottom pressurizing device 11 and the top pressurizing device 13 are brought close to each other to pressurize the multi-layer cavity assembly 12, thereby realizing multi-layer multi-cavity hot pressing sintering, effectively utilizing the horizontal and vertical sintering space in the furnace, increasing the single furnace loading capacity of sintered products, improving the sintering efficiency, and reducing the sintering cost. ; The top pressure device 13 acts directly on the topmost cavity assembly 12. When the bottom pressure device 11 and the top pressure device 13 are close to each other, the green billets 16 in the cavity assembly 12 are compressed by the pressure transfer between the layers of cavity assemblies 12. The products that reach the compression design height first are no longer compressed, while the products that have not reached the compression design height continue to be compressed during the pressure transfer process, so that each layer of green billets 16 can be compressed to the design height, thereby improving the consistency of the height and density of the same batch of sintered products, and on the basis of increasing the output of a single batch of sintered products, improving the size and density yield of a single batch of sintered products.

[0053] Furthermore, the change in the distance between the top pressurizing device 13 and the bottom pressurizing device 11 can be achieved by simply driving the top pressurizing device 13 or the bottom pressurizing device 11 to move, or the change in the distance between the top pressurizing device 13 and the bottom pressurizing device 11 can be achieved by driving the top pressurizing device 13 and the bottom pressurizing device 11 to move together.

[0054] It is understood that the mold cavity assembly 12 can be provided with multiple layers or only one layer. As a preferred embodiment, the mold cavity assembly 12 is provided with multiple layers to sinter more products of the same height and density in the same batch in the furnace of the same volume.

[0055] Furthermore, the spacing between the mold cavities 123 and the margins of the mold cavities 123 are sufficient to ensure that the mold cavity plate 122 does not break during the hot pressing and sintering process of the green body 16 .

[0056] In some examples, depending on the shape requirements of the product, the cavity plate 122 can be composed of multiple single molds, such as Figure 4 , a green body 16 is placed in the mold cavity 123 of the single mold, so that the green body 16 after hot pressing and sintering is adapted to the shape of the mold cavity 123 of the single mold, and a product of the desired shape is sintered.

[0057] like Figure 1 and Figure 2 As shown, in a feasible embodiment, there are N mold cavities 123 on each layer of mold cavity plate 122, each mold cavity 123 is vertically aligned with the mold cavity 123 at the corresponding position on the mold cavity plate 122 of the previous layer, and each mold cavity 123 is vertically aligned with the mold cavity 123 at the corresponding position on the mold cavity plate 122 of the next layer, so as to reduce the pressure difference on both sides of the mold cavity pad 121.

[0058] In this technical solution, when multiple layers of cavity assemblies 12 are stacked and each layer of cavity assemblies 12 is provided with multiple cavities 123, the cavities 123 at corresponding positions on the cavity plates 122 of each layer are aligned in the vertical direction to reduce the pressure difference between the upper and lower sides of the cavity pad 121, so that the thickness of the cavity pad 121 can be set smaller to reduce the overall height of the mold and reduce the occupation of the longitudinal sintering space of the furnace. More layers of cavity assemblies 12 can be arranged, thereby further increasing the loadable capacity in the uniform temperature area, and further increasing the single furnace load capacity of sintered products, thereby improving the hot pressing sintering efficiency.

[0059] like Figure 1 and Figure 2 As shown, in a feasible embodiment, the hot pressing sintering mold structure also includes: a first pad 14, the first pad 14 is arranged in the mold cavity 123, the first pad 14, the first pressure head 133 and the mold cavity 123 correspond one to one; the side wall of the first pad 14 is in contact with the mold cavity plate 122, the bottom surface of the first pad 14 is in contact with the top surface of the mold cavity pad 121, and the green body 16 is placed on the first pad 14.

[0060] In this technical solution, a first pad 14 is provided in the mold cavity 123 corresponding to each first pressing head 133, and the green body 16 is placed in the mold cavity 123 and above the first pad 14. As the hot pressing sintering densification process proceeds, the first pressing head 133 gradually enters the corresponding mold cavity 123. When the first pressing head 133 enters the corresponding mold cavity 123 and no longer moves, the molding height of the sintered product in the mold cavity 123 corresponding to the first pressing head 133 is determined.

[0061] like Figure 1 and Figure 2 As shown, in a feasible embodiment, the hot pressing sintering mold structure also includes: a second ram 15 assembly, the second ram 15 assembly is arranged on the bottom surface of the cavity pad 121 between two adjacent layers of cavity plates 122, the second ram 15 assembly includes Q second rams 15, Q=P, the second ram 15 corresponds one-to-one to the cavity 123 on the cavity plate 122 of the next layer, and the second ram 15 is used to pressurize the green body 16 in the cavity plate 122 of the next layer; a second pad 17, the second pad 17 is arranged in the cavity 123, the second pad 17 and the second ram 15 correspond one-to-one to the cavity 123; the side wall of the second pad 17 is in contact with the cavity plate 122, the bottom surface of the second pad 17 is in contact with the top surface of the cavity pad 121, and the green body 16 is placed on the second pad 17.

[0062] In this technical solution, a plurality of second pressing heads 15 are provided at the bottom of the cavity pad 121. The second pressing heads 15 are used to press the green billets 16 in a cavity assembly 12 adjacent to the lower layer of the cavity pad 121. That is, except for the green billets 16 in the top layer of the cavity assembly 12 being pressed by the first pressing head 133, the green billets 16 in the remaining layers of the cavity assembly 12 are all pressed by the second pressing heads 15 of the upper layer. The second pressing heads 15 transfer the pressing force to the green billets 16 during the hot pressing and sintering process to realize the transmission of the pressing force. The second pressing heads 15 cooperate with the first pressing heads 133 to realize the pressing molding of all the green billets 16. A second pad 17 is provided in the mold cavity 123 corresponding to each second press head 15, and the green body 16 is placed in the mold cavity 123 and located above the second pad 17. As the hot pressing and sintering densification process proceeds, the second press head 15 gradually enters the corresponding mold cavity 123. When the second press head 15 enters the corresponding mold cavity 123 and no longer moves, the molding height of the sintered product in the mold cavity 123 corresponding to the second press head 15 is determined.

[0063] In this technical solution, the product height is calculated as the height of the mold cavity 123 minus the corresponding pressure head height minus the corresponding spacer height. During pressure transfer between the various layers of the mold cavity assembly 12, the first spacer 14 and second spacer 17 within the mold cavity 123 allow the final molding height of each layer of green compact 16 to be adjusted, ensuring consistent heights across the sintered products. This allows for controllable heights across the entire batch of sintered products, ensuring high quality.

[0064] It should be noted that hot-pressed sintering furnaces have poorer temperature uniformity than pressureless sintering furnaces. There are certain temperature differences both horizontally and vertically within the furnace chamber. The actual uniform temperature zone is much smaller than the furnace chamber size. Even relatively small temperature differences within the uniform temperature zone can lead to inconsistent densification rates of green compacts 16 in different regions and inconsistent sample heights. By adjusting the inner diameter of the mold cavity 123, the diameter of the sintered product can be adjusted. Furthermore, by adjusting the weight of the pre-pressed green compact 16, the inner diameter of the mold cavity 123, the length of the first ram 133, the height of the spacer, and the height of the mold cavity 123, the size and density of the sintered product can be determined, achieving autonomous control of size and density.

[0065] It is understandable that the first pressing head 133 can be controlled to continue to move for pressurization by setting the margin of the first pressing head 133 that does not enter the mold cavity plate 122. The minimum margin is zero, that is, the top pressurizing device 13 is in contact with the top surface of the top mold cavity assembly 12.

[0066] In a feasible embodiment, the hot pressing sintering mold structure also includes: an isolation layer, which is arranged on the outside of the green body 16, the isolation layer separates the green body 16 from the first pressure head 133, the isolation layer separates the green body 16 from the first pad 14, and the isolation layer separates the green body 16 from the mold cavity plate 122; or, the isolation layer separates the green body 16 from the second pressure head 15, the isolation layer separates the green body 16 from the second pad 17, and the isolation layer separates the green body 16 from the mold cavity plate 122.

[0067] In this technical solution, the pre-pressed green body 16 is placed in the corresponding mold cavity 123, and an isolation layer is provided between the green body 16 and the inner wall of the mold cavity plate 122, the pressure head, and the pad, so that the green body 16 will not undergo high-temperature sintering and adhesion with the pressure head, the mold cavity plate 122 and the pad during the sintering process, which facilitates the demolding of the sintered product and protects the mold, and can improve the surface quality of the product.

[0068] As a preferred solution, the isolation layer is a graphite paper layer or a release agent coating.

[0069] like Figure 1 and Figure 2 As shown, in a feasible embodiment, the hot pressing sintering mold structure also includes: the top pressurizing device 13 includes: a first pressurizing column 131 and a first pressure plate 132; the first pressurizing column 131 is arranged on the pressurizing device, and the pressurizing device drives the first pressurizing column 131 to move; the first pressure plate 132 is arranged perpendicular to the first pressurizing column 131, the first side of the first pressure plate 132 is connected to the first pressurizing column 131, and the first pressure head 133 is vertically arranged on the second side of the first pressure plate 132.

[0070] In this technical solution, the diameter of the first pressurizing column 131 is much smaller than the inner diameter of the furnace. The first pressurizing column 131 is driven to move by the pressurizing equipment, and then the first pressure plate 132 is driven to move synchronously above the mold cavity assembly 12 for pressurization, thereby expanding the hot-pressing area of the first pressurizing column 131, thereby increasing the loading amount of green billets 16 in the single-layer mold cavity assembly 12, and increasing the loading amount of green billets 16 in the transverse direction of the furnace, thereby realizing effective utilization of the transverse space of the furnace.

[0071] It is understandable that the first pressing plate 132 needs to have a certain strength to ensure that no significant deformation occurs during the sintering process, thereby ensuring a high degree of precision of the product.

[0072] like Figure 1 and Figure 2 As shown, in a feasible embodiment, the bottom pressurizing device 11 includes: a second pressurizing column 111 and a second pressure plate 112; the second pressurizing column 111 is arranged on the pressurizing device, and the pressurizing device drives the second pressurizing column 111 to move; the second pressure plate 112 is arranged perpendicular to the second pressurizing column 111, and the first side of the second pressure plate 112 is connected to the second pressurizing column 111, and the second side of the second pressure plate 112 is in contact with the bottom layer of the cavity pad 121, and the second pressure plate 112 and the top pressurizing device 13 pressurize the cavity assembly 12 on both sides of the cavity assembly 12 respectively.

[0073] In this technical solution, the diameter of the second pressurizing column 111 is much smaller than the inner diameter of the furnace. The second pressurizing column 111 is driven to move by the pressurizing equipment, and then the second pressure plate 112 is driven to move synchronously under the mold cavity assembly 12 for pressurization, thereby expanding the hot-pressing area of the second pressurizing column 111, thereby increasing the loading amount of green billets 16 in the single-layer mold cavity assembly 12, and increasing the loading amount of green billets 16 in the transverse direction of the furnace, thereby effectively utilizing the transverse space of the furnace.

[0074] It is understandable that the second pressing plate 112 needs to have a certain strength to ensure that no significant deformation occurs during the sintering process, thereby ensuring a high degree of precision of the product.

[0075] Example 1:

[0076] The shell size of the hot pressing sintering furnace used is Φ1500mm×2100mm (diameter×height), and the furnace size is Φ800mm×1400mm. This embodiment describes a furnace with a size of Φ18.05mm×23.05mm and a density of 2.30g / cm 3 Boron carbide core blocks are hot pressed and sintered in batches, and the sintering mold material is high-strength isostatic graphite.

[0077] The size of the integral cavity plate used is Φ700mm×52mm, the inner diameter of the cavity is Φ18.4mm×52mm, and the cavity holes are arranged in a dense pattern, with a total of 349 cavity holes (see Figure 3), the dimensions of the first pad and the second pad are Φ18.2mm×3mm, and the dimensions of the first pressure head and the second pressure head are Φ18.2mm×25mm.

[0078] A sufficient amount of boron carbide green body was obtained by pre-pressing. The green body weighed 14.6g and had dimensions of approximately Φ18.0mm×42mm. A cavity backing plate measuring Φ700mm×20mm was placed on the bottom of the cavity plate and aligned. The first ram, second ram, first pad, second pad, and pre-pressed green body were properly assembled in the corresponding cavity holes. The contact between the green body and the graphite mold was isolated with graphite paper. After assembly, the first ram and second ram were respectively approximately 18mm higher than the corresponding cavity plate. Therefore, the total height of the cavity assembly (including the cavity backing plate and excluding the second ram) after the single-layer pre-installed green body was 90mm.

[0079] The dimensions of the first and second pressing plates are both Φ700mm×200mm to ensure sufficient strength of the pressing plates. After the first and second pressing plates are correctly combined with the mold cavity assembly with 10 layers of pre-loaded green billets outside the furnace body, the total dimensions are approximately Φ700mm×1300mm, which can load up to 3490 boron carbide core blocks.

[0080] The diameter of the furnace body pressure column is Φ350mm. The assembled mold is placed in the center of the furnace and tightened by the external mechanical device and the first and / or second pressure columns. After the furnace door is closed and vacuumed, hot pressing sintering is carried out. The sintering process is adjusted to reasonable temperature, time, and pressure process parameters. After hot pressing and sintering, a maximum of 3490 boron carbide core blocks (including graphite paper) with a size of Φ18.4mm×24mm are obtained by demolding. After machining and cleaning, the core blocks are approximately Φ18.05mm×23.05mm in size, and the measured density is basically 2.30g / cm 3 , height and density consistency are good.

[0081] Example 2:

[0082] The shell size of the hot pressing sintering furnace used is Φ1500mm×2100mm, and the furnace size is Φ800mm×1400mm. This embodiment describes the use of a split single-cavity mold to produce a sintered product with a size of Φ39.6mm / Φ30.4mm×29.1mm (outer diameter / inner diameter×height) and a density of 2.35g / cm 3 Batch hot pressing sintering of boron carbide annular core blocks, the sintering mold material is high-strength isostatic graphite.

[0083] The size of the split single-cavity mold used is Φ80mm / Φ40mm×80mm, the size of the inner graphite rod is Φ30mm×80mm, the size of the pressure head is Φ39.8mm / Φ30.2mm×40mm, and the size of the gasket is Φ39.8mm / Φ30.2×10mm.

[0084] A sufficient amount of boron carbide green body is obtained by pre-pressing. The green body weight is 39.2g and the green body size is Φ39.6mm / Φ30.4×50mm. The first pressing head, the second pressing head, the first pad, the second pad, the inner graphite rod and the pre-pressed green body are correctly assembled in the corresponding mold cavity hole. The contact between the green body and the graphite mold is isolated by graphite paper. After assembly, the first pressing head and the second pressing head are respectively about 20mm higher than the corresponding mold cavity. The size of the mold cavity pad is Φ700mm×40mm. Therefore, the total height of the hot pressing mold (including the mold cavity pad, excluding the second pressing head) after the single-layer pre-installed green body is 140mm. A total of 55 single-cavity molds can be arranged on the single-layer mold cavity pad (see Figure 4 ).

[0085] The dimensions of the first and second pressing plates are Φ700mm×200mm to ensure the strength of the pressing plates. After the first and second pressing plates are correctly combined with the hot pressing mold with 6 layers of pre-loaded green billets outside the furnace body, the total dimensions are approximately Φ700mm×1240mm, which can load and sinter up to 330 annular boron carbide core blocks.

[0086] The diameter of the furnace body pressure column is Φ350mm. The assembled mold is placed in the center of the furnace and tightened by the external mechanical device and the first and / or second pressure columns. After the furnace door is closed and vacuumed, hot pressing sintering is carried out. The sintering process is adjusted to reasonable temperature, time, and pressure process parameters. After hot pressing and sintering, a maximum of 330 annular boron carbide core blocks (including graphite paper) with a size of Φ40.0mm / Φ30.0mm×30.0mm are obtained by demolding. After machining and cleaning, the core blocks are approximately Φ39.6mm / Φ30.4mm×29.1mm in size, and the measured density is basically 2.35g / cm 3 , and can also ensure consistency in height and density.

[0087] like Figure 5 As shown, according to the second aspect of the present application, a hot pressing and sintering method is proposed, which is applied to the hot pressing and sintering mold structure of any of the above technical solutions, comprising:

[0088] Step 100: Design the number of layers of the mold cavity components, assemble the green body into the corresponding mold cavity holes, and then load the furnace;

[0089] Step 200: Calculate the total compression required for the green bodies in all layers of the mold cavity assembly, drive the top pressurizing device and / or the bottom pressurizing device, and pressurize and sinter the mold cavity assembly until the sum of the displacements of the top pressurizing device and / or the bottom pressurizing device approaches the difference between the total compression and the mold expansion; during the sintering process, the pressure column displacement reading changes simultaneously with the hot-pressing shrinkage of the green body height and the thermal expansion of the mold;

[0090] Step 300: Continue hot pressing and sintering until the displacement of the top pressurizing device and / or the bottom pressurizing device remains substantially unchanged, ensuring that the green compacts in all the mold cavity components shrink to the designed height, and completing the sintering process.

[0091] It can be understood that the hot pressing and sintering method provided in the embodiment of the present application is applied to the hot pressing and sintering mold structure of any of the above technical solutions, so the hot pressing and sintering method has all the beneficial effects of the hot pressing and sintering mold structure of the above technical solutions.

[0092] The hot pressing sintering method provided in the embodiment of the present application is characterized in that a multi-layer mold cavity assembly is arranged between a bottom pressurizing device and a top pressurizing device, and multiple mold cavities are arranged on each layer of the mold cavity assembly, so that the first pressure head corresponds to the mold cavity one by one, and the multi-layer mold cavity assembly is pressurized by bringing the bottom pressurizing device and the top pressurizing device close to each other to realize multi-layer and multi-cavity hot pressing sintering, effectively utilizing the horizontal and vertical sintering space in the furnace, increasing the single furnace loading capacity of sintered products, improving sintering efficiency, and reducing sintering costs; the top pressurizing device directly acts on the topmost mold cavity assembly, and when the bottom pressurizing device and the top pressurizing device are close to each other, the green billets in the mold cavity assembly are compressed by the pressure transfer between the mold cavity assemblies of each layer, and the products that reach the compression design height first are no longer compressed, while the products that do not reach the compression design height continue to be compressed during the pressure transfer process, so that each layer of green billets can be compressed to the design height, thereby improving the consistency of the height and density of the same batch of sintered products, and improving the size and density yield of the single batch of sintered products on the basis of improving the output of the single batch of sintered products.

[0093] Furthermore, the temperature, time and pressure in the hot pressing sintering process should be formulated to ensure that all layers of the green body can eventually shrink to the designed height, while minimizing the sintering temperature and shortening the holding time to prevent significant grain growth.

[0094] Specifically, the mold expansion can be obtained by measuring after multiple sintering cycles.

[0095] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0096] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A hot pressing sintering mold structure, characterized in that: The hot pressing and sintering mold structure comprises: Bottom pressure device; M cavity assemblies, wherein M cavity assemblies are stacked on the bottom pressurizing device along the height direction of the bottom pressurizing device, and M is greater than or equal to 1; The mold cavity assembly includes a mold cavity pad and a mold cavity plate, wherein the mold cavity plate is arranged on the mold cavity pad, and the mold cavity plate is provided with N mold cavities for placing green compacts, where N is greater than or equal to 2; A top pressurizing device, the top pressurizing device is arranged above the mold cavity assembly located at the top layer, and the bottom pressurizing device and the top pressurizing device are used to pressurize the mold cavity assembly; The top pressurizing device includes P first pressing heads, where P=N. The first pressing heads correspond to the mold cavities one by one, and the shapes of the first pressing heads are adapted to the shapes of the corresponding mold cavities.

2. A hot pressing sintering mold structure according to claim 1, characterized in that: There are N mold cavities on each layer of the mold cavity plate, each of the mold cavities is vertically aligned with the mold cavity at the corresponding position on the mold cavity plate of the previous layer, and each of the mold cavities is vertically aligned with the mold cavity at the corresponding position on the mold cavity plate of the next layer to reduce the pressure difference on both sides of the mold cavity pad.

3. The hot pressing sintering mold structure according to claim 1, characterized in that: The hot pressing and sintering mold structure also includes: a first cushion block, the first cushion block being disposed in the mold cavity, the first cushion block and the first pressing head corresponding to the mold cavity in a one-to-one manner; The side wall of the first cushion block is in contact with the mold cavity plate, the bottom surface of the first cushion block is in contact with the top surface of the mold cavity plate, and the green body is placed on the first cushion block.

4. The hot pressing sintering mold structure according to claim 3, characterized in that: The hot pressing and sintering mold structure further includes: A second pressing head assembly, the second pressing head assembly is arranged on the bottom surface of the cavity pad between two adjacent layers of the cavity plates, the second pressing head assembly includes Q second pressing heads, Q=P, the second pressing heads correspond one-to-one to the mold cavities on the cavity plate of the next layer, and the second pressing heads are used to pressurize the green body in the cavity plate of the next layer; a second cushion block, the second cushion block being disposed in the mold cavity, the second cushion block and the second pressing head corresponding to the mold cavity in a one-to-one manner; The side wall of the second cushion block is in contact with the mold cavity plate, the bottom surface of the second cushion block is in contact with the top surface of the mold cavity cushion plate, and the green compact is placed on the second cushion block.

5. The hot pressing sintering mold structure according to claim 4, characterized in that: The hot pressing and sintering mold structure also includes: an isolation layer, the isolation layer being arranged on the outside of the green body, the isolation layer separating the green body from the first pressing head, the isolation layer separating the green body from the first spacer, and the isolation layer separating the green body from the cavity plate; Alternatively, the isolation layer separates the green body from the second pressing head, the isolation layer separates the green body from the second spacer, and the isolation layer separates the green body from the cavity plate.

6. The hot pressing sintering mold structure according to claim 5, characterized in that: The isolation layer is a graphite paper layer or a release agent coating.

7. The hot pressing sintering mold structure according to claim 1, characterized in that: The hot pressing and sintering mold structure further includes: The top pressure device comprises: a first pressurizing column, wherein the first pressurizing column is provided on a pressurizing device, and the pressurizing device drives the first pressurizing column to move; A first pressing plate is arranged perpendicular to the first pressurizing column, a first side of the first pressing plate is connected to the first pressurizing column, and the first pressure head is arranged perpendicularly on the second side of the first pressing plate.

8. A hot pressing and sintering mold structure according to any one of claims 1 to 7, characterized in that: The bottom pressurizing device comprises: a second pressurizing column, the second pressurizing column being provided on a pressurizing device, the pressurizing device driving the second pressurizing column to move; The second pressure plate is arranged perpendicular to the second pressure column, the first side of the second pressure plate is connected to the second pressure column, the second side of the second pressure plate is in contact with the bottom layer of the cavity pad, and the second pressure plate and the top pressure device pressurize the cavity assembly on both sides of the cavity assembly respectively.

9. A hot pressing sintering method, characterized in that: Applicable to manufacturing a hot pressing and sintering mold structure according to any one of claims 1 to 8, the method comprising: Designing the number of layers of the mold cavity components of the mold, assembling the green body into the corresponding mold cavity, and then loading the furnace; Calculating the total compression required for the green compacts in all layers of the mold cavity assembly, driving the top pressurizing device and / or the bottom pressurizing device to move, and pressurizing and sintering the mold cavity assembly until the sum of the displacements of the top pressurizing device and / or the bottom pressurizing device approaches the difference between the total compression and the mold expansion; The hot pressing sintering is continued until the displacement of the top pressurizing device and / or the bottom pressurizing device remains substantially unchanged, so that the green compacts in all the mold cavity components are shrunk to the designed height, and the sintering process is completed.

Images