A reaction-sintered silicon carbide ribbed crossbeam and its special extrusion die and preparation method

Abstract

The invention discloses a reaction-sintered silicon carbide ribbed crossbeam and a special extrusion die and a preparation method thereof. The cross section of the crossbeam is a frame-shaped structure, and a reinforcing rib is arranged inside the frame-shaped structure, so that the load-bearing of two vertical surfaces is changed to three vertical surfaces; the special extrusion die comprises a die body, and the die body comprises an outer die and a core die, and the interior of the outer die is a hollow structure, the cross section of the hollow structure at the outlet end is rectangular, and the longitudinal section of the hollow structure at the inlet end is trumpet-shaped; one end of the core die is a fixed end, and the other end is provided with two forks, the cross sections of the two forks are rectangular, and the strip space between the two forks forms the ribs of the crossbeam; and the extrusion molding process is adopted for preparation; the advantages of the invention are: the blank structure is reasonable, the density is high and the wall thickness is uniform; the blank is dried uniformly without cracking; the product has high density and high bending strength; it can withstand high temperature of 1250°C and is not deformed during long-term use.

Description

Technical Field

[0001] The invention relates to a load-bearing crossbeam, which is used for a kiln car load-bearing main beam of a foam ceramic kiln, and specifically relates to a reaction-sintered silicon carbide ribbed crossbeam and a special extrusion die and a preparation method thereof, belonging to the field of sintered silicon carbide load-bearing crossbeams. Background Art

[0002] The load-bearing crossbeam is a kiln car support used for various kilns such as electrical porcelain, daily-use porcelain, sanitary porcelain, microcrystalline glass, and foam ceramics. It plays an important load-bearing role. Various auxiliary beams, shelf boards, and fired products are sintered under its support. Summary of the invention

[0003] The purpose of the present invention is to design a reaction sintered silicon carbide ribbed crossbeam and its special extrusion die and preparation method, so that the obtained load-bearing crossbeam can bear a load exceeding the national standard by 25% and can be used for a long time at a high temperature of 1250°C.

[0004] The technical solution of the present invention is:

[0005] A reaction-sintered silicon carbide ribbed crossbeam, the cross section of the crossbeam is a frame-shaped structure, a reinforcing rib is arranged inside the frame-shaped structure, and the load-bearing structure is changed from two vertical surfaces to three vertical surfaces; deformation can be prevented and structural strength is improved.

[0006] Wherein, the crossbeam is an extrusion molding structure.

[0007] Furthermore, the width of the reinforcing rib is 8 mm.

[0008] During production, various required raw materials are mixed together, put into a kneading machine, and adhesive and water are added for kneading. The kneaded mud material is then put into an extruder, and the extrusion die is installed at the discharge port of the extruder. Under the action of the spiral force of the extruder, the mud is extruded through the extrusion die to extrude the required square beam blank.

[0009] The special extrusion die for the above-mentioned reaction-sintered silicon carbide ribbed cross beam comprises a die body, wherein the die body comprises an outer die and a core die, wherein the interior of the outer die is a hollow structure, wherein the cross section of the hollow structure at the outlet end is rectangular, and the longitudinal cross section of the hollow structure at the inlet end is trumpet-shaped, so as to facilitate the addition of extruded materials; one end of the core die is a fixed end provided with a fixed thread, and the other end is provided with two forks, wherein the cross sections of the two forks are rectangular, and the strip space between the two forks forms the vertical ribs of the cross beam, and the cross beam is extruded between the outer die and the core die.

[0010] Furthermore, an extrusion material inlet is provided at the beginning of the fork, and the extrusion material inlet is an inclined surface structure, and the width gradually decreases and the depth gradually increases, and the minimum width is equal to the distance between the two forks.

[0011] Furthermore, the width of the extrusion material inlet at the beginning is 20 mm, and the width at the end is 8 mm.

[0012] Furthermore, there are two extrusion material inlets, which are respectively arranged on both sides of the core mold, thereby solving the problem of synchronous extrusion of the peripheral and middle ribs. If they are not synchronized, it will cause cracks in the blank and inconsistent density between the internal ribs and the peripheral ribs.

[0013] The method for preparing the reaction-sintered silicon carbide ribbed cross beam adopts an extrusion molding process and specifically comprises the following steps:

[0014] (1) Mixing various raw materials required for reaction sintered silicon carbide ribbed beams;

[0015] (2) Put the mixed material into a kneader, add a binder and deionized water, and knead until it becomes a mud-like state;

[0016] (3) The kneaded mud material is placed in the feed bin of the extruder for extrusion. Under the driving force of the screw shaft, the mud is pushed through the die to form a beam blank;

[0017] (4) After the extruded green body is baked, it is placed in a high-temperature vacuum sintering furnace at 1750°C for high-temperature vacuum sintering to the required temperature. The furnace is stopped and cooled to 300°C before being taken out of the furnace to obtain the desired finished square beam;

[0018] (5) The finished products are cleaned with rough sand and subjected to load-bearing capacity test, then polished and sandblasted.

[0019] The key to synchronous discharge is mold processing, that is, the 8mm rib, the tail feed end is gathered from 20mm width to 8mm width, so that there can be enough material mud to the position of the rib and then extruded through the mold under the action of rotational force.

[0020] The present invention adopts an extrusion molding process: in order to synchronize the discharge of the periphery and the middle rib during extrusion, the rear part of the 8mm space of the middle rib in the mold core is opened to 20mm wide and the rear part is deep and the front part is shallow, so as to achieve sufficient feeding, synchronize the discharge of the middle rib and the periphery, and thus make the density of the blank uniform.

[0021] Furthermore, the inner wall of the crossbeam blank obtained in step (3) is treated by steam blowing drying to solve the problem of uniform drying of the blank. Since the space between the two holes in the crossbeam is small, the air in the inner holes does not flow, which causes the blank cracks to be generated due to the asynchronous drying of the outer surface.

[0022] Furthermore, the method for drying the green body is as follows: put the extruded green body on the drying rack, insert a thin tube into the two rectangular holes of each beam respectively to pass steam; dry it indoors to solve the problem of asynchronous drying of the inner and outer surfaces and the problem of green body cracks caused by asynchronous drying. After ventilating for 24 hours, stop ventilating and put it into a low-temperature baking room, dry it at 40℃-50℃ for 30 hours, then transfer it to a high-temperature baking room, bake it at 60℃-70℃ for 24 hours, and then take out the green body for sintering.

[0023] The advantages of the invention are: reasonable body structure, high density and uniform wall thickness; uniform drying of the body without cracking; high density and high bending strength of the product; high temperature resistance of 1250°C and long-term use without deformation.

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a cross-sectional view of a reaction-sintered silicon carbide ribbed beam according to an embodiment of the present invention;

[0026] Figure 2 It is a longitudinal cross-sectional view of the outer die of a special extrusion die for reaction-sintered silicon carbide ribbed cross beam according to an embodiment of the present invention;

[0027] Figure 3 for Figure 2 Cross-sectional view at plane AA;

[0028] Figure 4 This is a schematic structural diagram of a special extrusion die core mold for a reaction-sintered silicon carbide ribbed cross beam according to an embodiment of the present invention;

[0029] In the figure:

[0030] 1-crossbeam, 2-frame structure, 3-reinforced vertical ribs, 4-elevation, 11-external mold, 12-core mold, 13-hollow structure, 14-export end, 15-trumpet shape, 16-fixed end, 17-bifurcation, 18-strip space, 19-extrusion material inlet. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] Examples, such as Figure 1 As shown, a reaction-sintered silicon carbide ribbed cross beam, the cross section of the cross beam 1 is a frame-shaped structure 2, and a reinforcing vertical rib 3 is arranged inside the frame-shaped structure 2, so that the load-bearing is changed from two vertical surfaces 4 to three vertical surfaces 4; deformation can be prevented and structural strength is improved.

[0033] The cross beam is an extrusion-molded structure. The width of the reinforcing rib is 8 mm.

[0034] During production, the required raw materials (traditional raw materials: 3-10 micron micropowder, 3-5 micron carbon powder) are mixed together, put into a kneading machine, and an adhesive (traditional binder) and water are added for kneading. The kneaded mud material is then put into an extruder, and the extrusion die is installed at the discharge port of the extruder. Under the action of the spiral force of the extruder, the mud is extruded through the extrusion die to extrude the required square beam blank.

[0035] like Figure 2-4 As shown, a special extrusion die for the above-mentioned reaction sintered silicon carbide ribbed cross beam comprises a die body, wherein the die body comprises an outer die 11 and a core die 12, wherein the interior of the outer die 11 is a hollow structure 13, wherein the cross section of the hollow structure 13 at the outlet end 14 is rectangular, and the longitudinal section of the hollow structure 13 at the inlet end is a trumpet shape 15, which is convenient for adding extruded materials; one end (inlet end) of the core die 12 is a fixed end 16, provided with a fixed thread, and the other end (outlet end) is provided with two forks 17, wherein the cross section of the two forks 17 is rectangular, and the strip space 18 between the two forks 17 forms the vertical ribs 3 of the cross beam, and the cross beam is extruded between the outer die and the core die.

[0036] The beginning of the bifurcation 17 is provided with an extrusion material inlet 19, which is an inclined surface structure, and the width gradually decreases, the depth gradually increases, and the minimum width is equal to the distance between the two bifurcations 17. The width of the extrusion material inlet at the beginning is 20mm, and the width at the end is 8mm. There are two extrusion material inlets 19, which are respectively arranged on both sides of the core mold, thereby solving the problem of synchronous extrusion of the peripheral and middle ribs. If they are not synchronized, it will cause cracks in the blank and the density of the inner ribs will be inconsistent with that of the peripheral ribs.

[0037] The method for preparing the reaction-sintered silicon carbide ribbed cross beam adopts an extrusion molding process and specifically comprises the following steps:

[0038] (1) Mix various raw materials (conventional configuration) required for reaction sintered silicon carbide ribbed beams;

[0039] (2) Put the mixed material into a kneader, add a binder (traditional binder) and deionized water, and knead until it becomes a mud-like state;

[0040] (3) Put the kneaded mud material into the feed bin of the extruder (extrusion pressure 7-9Kg) for extrusion. Under the push of the rotating force of the screw shaft, the mud is pushed through the mold to form a crossbeam blank;

[0041] (4) After the extruded green body is baked, it is placed in a high-temperature vacuum sintering furnace at 1750°C for high-temperature vacuum sintering to the required temperature. The furnace is stopped to cool down (300°C) and then taken out of the furnace to obtain the desired finished square beam;

[0042] (5) The finished products are cleaned with rough sand and subjected to load-bearing capacity test, then polished and sandblasted.

[0043] The key to the synchronous discharge method is mold processing, that is, the 8mm rib, the tail feed end is gathered from 20mm width to 8mm width, so that there can be enough material mud to the position of the rib and then extruded through the mold under the action of rotational force.

[0044] The present invention adopts an extrusion molding process: in order to synchronize the discharge of the periphery and the middle rib during extrusion, the rear part of the 8mm space of the middle rib in the mold core is opened to 20mm wide and the rear part is deep and the front part is shallow, so as to achieve sufficient feeding, synchronize the discharge of the middle rib and the periphery, and thus make the density of the blank uniform.

[0045] The inner wall of the beam blank obtained in step (3) is treated by steam blowing drying to solve the problem of uniform drying of the blank. Since the space between the two holes in the middle of the beam is only 10x69 rectangular holes 3600mm long, the air in the inner holes does not flow, resulting in the drying of the blank not being synchronized with the outer surface, resulting in cracks in the blank.

[0046] The method for drying the green body is as follows: put the extruded green body on the drying rack, insert a thin tube into the two 10x69 rectangular holes of each crossbeam and pass steam. Dry it naturally indoors to solve the problem of asynchronous drying of the inner and outer surfaces and the problem of green body cracks caused by asynchronous drying. After ventilating for 24 hours, stop ventilating and put it into a low-temperature baking room, dry it at 40℃-50℃ for 30 hours, then transfer it to a high-temperature baking room, bake it at 60℃-70℃ for 24 hours, and then take out the green body for sintering.

[0047] The crossbeam produced by the present invention has the following test comparison indicators:

[0048] index unit This embodiment Traditional Practice Body density g / cm³ 2.16 2.15 Product density g / cm³ 3.05 0.645 Bending strength Concentration force kg per piece 197 275 Silicon carbide content % 85.5 85

[0049] It can be seen from the comparison of the above data that the bending strength of the beam produced by the present invention is significantly improved compared with the product produced by the traditional process, which solves the problem raised by the user and saves a lot of kiln tool costs for foam ceramic manufacturers.

[0050] According to the test, the green body density obtained by the present invention reaches above 2.16g / cm³, the density of the sintered product reaches 3.05g / cm³, and the bending strength of a single concentrated force reaches 260kg.

[0051] Each load-bearing main beam of the kiln car is required to bear a concentrated load of 260 kg. The specifications of the beam are 45x85x8x3600mm. According to national standards, the theoretical load-bearing capacity of the beam is 197kg.

[0052] The raw materials used in the present invention are all commonly used raw materials in production in this field, can be obtained from the market, and will not affect the production results; the various equipment used in the present invention are all conventional equipment used in the production process in this field, and the operation and parameters of each equipment are carried out in accordance with conventional operations, and there is nothing special.

Claims

1. A special extrusion die for reaction sintered silicon carbide ribbed beams, characterized in that: The cross section of the reaction-sintered silicon carbide ribbed cross beam is a frame-shaped structure, and a reinforcing rib is provided inside the frame-shaped structure, so that the load-bearing surfaces change from two vertical surfaces to three vertical surfaces; The crossbeam is an extrusion-molded structure; The width of the reinforcing rib is 8mm; The special extrusion mold includes a mold body, which includes an outer mold and a core mold. The interior of the outer mold is a hollow structure, the cross-section of the hollow structure at the outlet end is rectangular, and the longitudinal section of the hollow structure at the inlet end is trumpet-shaped; one end of the core mold is a fixed end, and the other end is provided with two forks, the cross-sections of the two forks are rectangular, and the strip space between the two forks forms the vertical ribs of the beam.

2. The special extrusion die according to claim 1, characterized in that: An extrusion material inlet is arranged at the beginning of the fork, and the extrusion material inlet is an inclined surface structure, and the width gradually decreases and the depth gradually increases, and the minimum width is equal to the distance between the two forks.

3. The special extrusion die according to claim 2, characterized in that: The width of the extrusion material inlet is 20 mm at the beginning and 8 mm at the end.

4. The special extrusion die according to claim 3, characterized in that: The extrusion material inlet is provided with two, which are respectively arranged on both sides of the core mold.

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