A cold-pressing die suitable for boron nitride powder

Abstract

This utility model discloses a cold pressing mold suitable for boron nitride powder, comprising: a cylinder, a filter bag, a press head, and a base. The cylinder and press head are separately arranged. The upper and lower ends of the cylinder are open. The filter bag is placed inside the cylinder and placed on the base together with the cylinder. The outer wall of the cylinder has evenly arranged vent holes. The filter bag is used to hold the boron nitride powder to be cold pressed. The press head is a hollow cylinder. This mold is used to cold press boron nitride powder to increase the powder bulk density, thereby increasing the filling amount of the hot pressing mold in the subsequent hot pressing sintering step.

Description

Technical Field

[0001] This utility model relates to the field of boron nitride processing technology, and in particular to a cold pressing mold suitable for boron nitride powder. Background Technology

[0002] Vacuum hot pressing sintering technology is widely used in the preparation of functional ceramic green bodies. This technology allows for the production of various functional ceramics from powder, such as corundum ceramics, boron carbide ceramics, silicon nitride ceramics, and high-density graphite green bodies. High-purity hexagonal boron nitride ceramics are obtained by sintering micron-sized boron nitride powder in a vacuum hot pressing furnace at temperatures above 1800℃ and pressures of tens of megapascals. Compared to other ceramic powder raw materials, boron nitride ceramic powder is characterized by its very low bulk density, only 250 ~ 350 kg / m³. 3 The density of hexagonal boron nitride hot-pressed ceramics is typically 2000~2100 kg / m³. 3 When filling a mold with powder, approximately six-sevenths of the material is porous. Therefore, the production efficiency of directly filling a hot-press mold with boron nitride powder is very low. It is necessary to increase the density of the raw material to 1000 kg / m³ before hot pressing and sintering. 3 above.

[0003] As described in CN202010771468.6, in the boron nitride ceramics industry, cold pressing in a hot-press mold is commonly used to increase density. However, because boron nitride powder is flake-shaped, it forms an orientation after cold pressing. This means that when sintering a relatively large block, if filling continues directly after cold pressing, an interface will appear between the two fillings, which is difficult to bond even during hot pressing and sintering. This leaves obvious interface marks or even cracks that do not heal properly after sintering. Patent CN202010922421.5 chooses to demold after cold pressing, re-crush the cold-pressed block into granules, and then re-fill. The problem with this method is that although the bulk density of the obtained granules can reach approximately 1200~1300 kg / m³, 3 However, the blank formed by cold pressing will get stuck in the mold and be difficult to demold, especially for larger and taller molds.

[0004] Therefore, a mold for cold-pressing boron nitride powder is provided, which can increase the bulk density of boron nitride powder to about 1000 kg / m³. 3 This avoids the problem of compacted powder being difficult to demold under high pressure. Utility Model Content

[0005] In view of this, the present invention discloses a cold pressing mold suitable for boron nitride powder. The boron nitride powder is cold pressed by the mold to increase the bulk density of the powder, thereby increasing the filling amount of the hot pressing mold in the subsequent hot pressing sintering step.

[0006] The technical solution of this utility model includes: a cold pressing mold suitable for boron nitride powder, comprising: a cylinder, a filter bag, a press head and a base, wherein the cylinder and the press head are separately arranged, the upper and lower ends of the cylinder are open, the filter bag is placed inside the cylinder, and the filter bag and the cylinder are placed together on the base, the outer wall of the cylinder is provided with evenly arranged vent holes, the filter bag is used to hold the boron nitride powder to be cold pressed, and the press head is a hollow cylinder.

[0007] Preferably, two handles are symmetrically provided on both sides of the upper outer wall of the cylinder.

[0008] Preferably, the filter bag body is made of polypropylene.

[0009] Preferably, when the filter bag contains the boron nitride powder to be cold-pressed, the filter bag is in a sealed state. Preferably, the opening of the filter cloth belt can be closed.

[0010] Preferably, the filter bag is equipped with a filter bag handle.

[0011] Preferably, the side of the base body is pre-fabricated with forklift fork holes.

[0012] Preferably, the diameter of the pressure head is smaller than the inner diameter of the cylinder.

[0013] Preferably, the upper part of the pressure head is provided with a lifting ring interface and a detachable lifting ring.

[0014] This invention provides a cold pressing mold suitable for boron nitride powder. The outer wall of the mold cylinder has rows of vent holes, and the raw material is wrapped in a filter bag inside the cylinder. This facilitates the removal of large amounts of air squeezed out during compaction and effectively prevents dust leakage. Using this mold in conjunction with a cold press, the density of boron nitride powder for hot pressing sintering can be reduced from 250 to 350 kg / m³. 3 Increased to approximately 1000 kg / m 3 .

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of this utility model. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A front view of a cold pressing mold suitable for boron nitride powder, provided in an embodiment of this utility model; Figure 2 A three-dimensional structural schematic diagram of a cold pressing mold suitable for boron nitride powder, provided for an embodiment of this utility model; Figure 3 This is a schematic diagram of the press head structure in a cold pressing mold suitable for boron nitride powder, provided by an embodiment of the present invention. Figure 4 This is a schematic diagram of the usage state of a cold pressing mold suitable for boron nitride powder, provided in an embodiment of this utility model. Detailed Implementation

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention. Rather, they are merely examples of systems consistent with some aspects of this invention as detailed in the appended claims.

[0020] like Figure 1-2 As shown, this embodiment provides a cold pressing mold suitable for boron nitride powder, including: a cylinder 1, a filter bag 4, a pressing head 8 and a base 6, wherein the cylinder and the pressing head 8 are separately arranged; The filter bag 4 is placed inside the cylinder. The upper and lower ends of the cylinder are open. The cylinder has a cylindrical structure and is used to withstand the radial pressure transmitted by the boron nitride powder during cold pressing. Two handles are symmetrically installed on the upper part of the outer wall of the cylinder for easy movement.

[0021] The outer wall of the cylinder is provided with several rows and columns of evenly arranged vent holes 3, which are used to discharge the gas in the boron nitride powder when it is squeezed by the mold. The filter bag 4 is used to hold the boron nitride powder to be cold-pressed, and also to discharge the gas in the boron nitride powder to be cold-pressed during the cold pressing process, while restraining the boron nitride powder from scattering. The filter bag 4 mentioned above is made of polypropylene, which can be obtained from existing technologies.

[0022] The volumes of the aforementioned cylinder 1 and filter bag 4 are approximately the same. When the filter cloth belt contains boron nitride powder, the filter bag is sealed using existing technical means, such as a pull rope seal or a cross-sealing method using the handle.

[0023] The filter bag 4 is equipped with a filter bag handle 5, which can be lifted out of the entire filter bag along with the boron nitride cold-pressed product using lifting equipment after cold pressing.

[0024] The filter bag 4 is placed on the base 6 together with the cylinder 1. The base 6 provides support for the cylinder 1 and the filter bag 4, and also bears the pressure transmitted from the pressure head 8 during cold pressing. The base 6 has pre-drilled forklift fork holes 7 for easy movement of the mold by forklift.

[0025] The pressure head 8 is a hollow cylinder with a diameter matching the outer wall of the mold. It is equipped with a lifting ring interface 9 and a detachable lifting ring 10 for easy lifting with lifting equipment. The lifting ring interface 9 allows for easy screwing in and removing of the lifting ring, facilitating the raising and lowering of the pressure head. The mold provided in this embodiment can be used with a cold press to reduce the density of boron nitride powder used for hot pressing and sintering from 250 to 350 kg / m³. 3 Increased to approximately 1000 kg / m 3 .

[0026] When using the cold pressing mold for boron nitride powder provided in this embodiment, the cylinder 1 is placed in the center of the base 6, the filter bag 4 is placed inside the cylinder 1, the boron nitride material to be pressed is placed into the filter bag 4 and wrapped by the filter bag 4. The handle 5 of the filter bag 4 is placed on the outside to prevent it from being pressed into the boron nitride material.

[0027] Install the lifting ring 10 onto the pressure head, lift it into the cylinder 1, remove the lifting ring 10, and complete the mold installation process.

[0028] Use a forklift to lift the mold, once assembled, from the fork holes 7 on the base 6 and place it in the cold press. Remove the forklift and start the cold press to complete the cold pressing operation.

[0029] Use a forklift to remove the molded die from the cold press through the forkhole 7 on the base. After removing the forklift, attach the lifting ring to the press head. Use lifting tools to lift the press head 8 and place it in the designated location for future use. Continue using lifting tools to lift the filter bag 4 using the handle to complete the demolding. After demolding, clean the cylinder and filter bag and place them in the designated location for future use.

[0030] The present invention will be further explained and described below with specific embodiments, but these are not intended to limit the scope of protection of the present invention.

[0031] Example 1 Place the 50cm diameter, 60cm high cylinder of the mold in the center of the base. Insert the filter bag into the cylinder, and then fill the filter bag with 30kg of boron nitride material to be pressed until it almost completely fills the internal space. Seal the filter bag with the filter bag. Place the handle of the filter bag on the outside to prevent it from being pressed into the boron nitride material.

[0032] Attach the lifting ring to the pressure head and lift it into the mold cylinder. At this point, due to gravity, the pressure head will press the material in to a depth of several centimeters. Remove the lifting ring to complete the mold installation process.

[0033] Use a forklift to lift the molded part from the fork holes on the base and place it on the cold press. Remove the forklift, start the cold press, set the hydraulic pressure to a constant 25MPa, and set the time to 5 minutes to complete the cold pressing operation.

[0034] Using a forklift, remove the molded die from the cold press through the forkholes on the base. After removing the forklift, attach the lifting ring to the press head. Use lifting tools to lift the press head and place it in the designated location for future use. Continue using lifting tools to lift the filter bag from the handle, completing the demolding process and transferring the product to the next hot pressing process. After demolding, clean the cylinder and filter bag and place them in the designated location for future use.

[0035] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0036] It should be understood that this invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

Claims

1. A cold pressing mold suitable for boron nitride powder, characterized in that, include: The cylinder (1), filter bag (4), press head (8) and base (6) are separate. The upper and lower ends of the cylinder are open. The filter bag (4) is placed inside the cylinder and placed on the base (6) together with the cylinder (1). The outer wall of the cylinder (1) is provided with evenly arranged exhaust holes (3). The filter bag (4) is used to hold the boron nitride powder to be cold-pressed. The press head (8) is a hollow cylinder.

2. The cold pressing mold for boron nitride powder according to claim 1, characterized in that, The upper outer wall of the cylinder (1) is symmetrically provided with two handles (2).

3. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The filter bag (4) is made of polypropylene.

4. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, When the filter bag (4) holds the boron nitride powder to be cold-pressed, the filter bag (4) is in a sealed state.

5. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The opening of the filter bag (4) can be closed.

6. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The filter bag (4) is equipped with a filter bag handle (5).

7. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The base (6) body has forklift fork holes (7) pre-made on the side.

8. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The diameter of the pressure head (8) is smaller than the inner diameter of the cylinder (1).

9. A cold pressing mold suitable for boron nitride powder according to claim 1, characterized in that, The upper part of the pressure head (8) is provided with a lifting ring interface and a detachable lifting ring.

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