Downward pressing rod assembly

Abstract

A down-pressing rod chock plug is of a solid structure, the down-pressing rod chock plug sequentially comprises a surface layer, a gradient transition layer and a base body layer from outside to inside, the surface layer, the gradient transition layer and the base body layer sequentially form a gradient structure, the surface layer is made of a high-hardness ceramic material, the gradient transition layer is made of a metal ceramic composite material, and the gradient transition layer is made of a metal ceramic composite material. The base body layer is made of Cr-Mo alloy steel materials, the high-hardness layer on the surface layer is beneficial for reducing abrasion, the base body layer is a ductile layer, overall brittle failure and bursting of the down-pressing rod chock plug are avoided, the service life of the down-pressing rod chock plug is prolonged by 30% or above, stress can be effectively dispersed through the gradient structure of the down-pressing rod chock plug, the surface layer is made of high-hardness ceramic materials, powder adhesion can be reduced, and the service life of the down-pressing rod chock plug is prolonged by 30% or above. The surface smoothness of a formed part is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy die processing, and specifically to a downward pressing rod assembly. Background Art

[0002] Powder Metallurgy (PM) is an advanced manufacturing technology for manufacturing materials or parts through the forming and sintering of metal or non-metal powders. It is widely used in modern industries such as automotive, aerospace, electronics, and medical fields, and has advantages such as near-net shaping, high material utilization rate, and adjustable material properties.

[0003] When powder metallurgy pre-processes metal powders, it is usually necessary to assemble a downward pressing rod assembly and a plug together on a powder forming rotary press to extrude the metal powders to be processed, so that the metal powders are formed. Because the pressure required during the metal powder forming process is relatively large, and the existing plugs are usually hollow structures, so during the metal powder forming process, it is very easy to cause the plug to burst, affecting the processing progress and increasing the processing cost at the same time. Summary of the Invention

[0004] Based on this, it is necessary to provide a downward pressing rod assembly, which can effectively solve the problem of plug bursting due to excessive pressure during the metal powder processing.

[0005] A downward pressing rod assembly includes a downward pressing rod plug, a screw, a downward pressing rod bushing, and a downward pressing rod;

[0006] The screw is threadedly connected to the downward pressing rod plug, the downward pressing rod bushing is sleeved on the screw, the downward pressing rod is sequentially sleeved on the downward pressing rod bushing and the downward pressing rod plug, the top of the screw has a mounting hole, and both sides of the downward pressing rod are provided with notches, and both ends of the mounting member are clamped in the notches after passing through the mounting hole;

[0007] The downward pressing rod plug has a solid structure. The downward pressing rod plug sequentially includes a surface layer, a gradient transition layer, and a matrix layer from the outside to the inside. The surface layer, the gradient transition layer, and the matrix layer form a gradient structure. The surface layer is made of a high-hardness ceramic material, the gradient transition layer is made of a metal-ceramic composite material, and the matrix layer is made of a Cr-Mo alloy steel material.

[0008] In one embodiment, the high-hardness ceramic material is one of alumina or silicon carbide.

[0009] In one embodiment, the metal-ceramic composite material is a gradient mixture of WC-Co and steel.

[0010] In one embodiment, the surface layer has a laser-textured micro-pit array, and the micro-pits are filled with a solid lubricant.

[0011] In one embodiment, the depth of the micro-pit array is 10 μm - 30 μm.

[0012] In one embodiment, the gradient transition layer is dispersed with TiC nanowires, and the diameter of the TiC nanowires is 50 nm - 100 nm, and the aspect ratio > 20.

[0013] In one embodiment, the pressing rod assembly further includes a plug head backing plate, and the plug head backing plate is sleeved on the plug head of the pressing rod and abuts against the inner layer of the pressing rod.

[0014] In one embodiment, the surface layer has an Al2O3 - Y2O3 composite coating.

[0015] In one embodiment, the Al2O3 - Y2O3 composite coating is formed on the micro-pit array of the surface layer by laser cladding.

[0016] In one embodiment, the depth of the micro-pit is 10% - 15% of the thickness of the Al2O3 - Y2O3 composite coating.

[0017] In the above-mentioned pressing rod assembly, the plug head of the pressing rod is of a solid structure. The plug head of the pressing rod sequentially includes a surface layer, a gradient transition layer, and a matrix layer from the outside to the inside. The surface layer, the gradient transition layer, and the matrix layer form a gradient structure in sequence. The surface layer is made of a high-hardness ceramic material, the gradient transition layer is made of a cermet composite material, and the matrix layer is made of a Cr-Mo alloy steel material. The high-hardness layer of the surface layer is beneficial to reducing wear, and the matrix layer is a tough layer to avoid the overall brittle fracture and explosion of the plug head of the pressing rod. The service life of the plug head of the pressing rod is increased by more than 30%. The gradient structure of the plug head of the pressing rod can effectively disperse stress. The surface layer is made of a high-hardness ceramic material, which can reduce powder adhesion and improve the surface finish of the formed part. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a pressing rod assembly according to an embodiment of the present invention;

[0019] Figure 2 is Figure 1 a schematic cross-sectional structural diagram of a pressing rod assembly according to an embodiment of the present invention;

[0020] Figure 3 is Figure 2 a schematic cross-sectional structural diagram of a plug head of a pressing rod assembly according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings. A lot of specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0022] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element present at the same time. In contrast, when an element is referred to as being "directly" connected to another element, there is no intermediate element.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0024] As Figure 1 、 Figure 2 shown, a pressing rod assembly includes a pressing rod plug 1, a screw 2, a pressing rod bushing 3, and a pressing rod 4;

[0025] The screw 2 is threadedly connected to the pressing rod plug 1. The pressing rod bushing 3 is sleeved on the screw 2. The pressing rod 4 is sequentially sleeved on the pressing rod bushing 3 and the pressing rod plug 1. The top of the screw 2 has a mounting hole 21. Notches 41 are formed on both sides of the pressing rod 4. After the mounting member passes through the mounting hole 21, both ends are clamped in the notches 41.

[0026] As Figure 3 shown, the pressing rod plug 1 has a solid structure. The pressing rod plug 1 sequentially includes a surface layer 11, a gradient transition layer 12, and a matrix layer 13 from the outside to the inside. The surface layer 11, the gradient transition layer 12, and the matrix layer 13 form a gradient structure. The surface layer 11 is made of a high-hardness ceramic material. The gradient transition layer 12 is made of a cermet composite material. The matrix layer 13 is made of a Cr-Mo alloy steel material.

[0027] The high-hardness ceramic material is one of alumina or silicon carbide. The cermet composite material is a gradient mixture of WC-Co and steel.

[0028] The lower pressure rod plug 1 is a solid structure, and the surface layer 11, the gradient transition layer 12 and the base layer 13 form a gradient structure, so that the lower pressure rod plug 1 forms a hard outer and tough inner structure. The surface layer 11 is a high hardness layer that can effectively resist wear, and the internal high toughness matrix (such as Cr-Mo steel) absorbs impact and avoids brittle failure. The performance of the lower pressure rod plug 1 is gradually changed to avoid sudden changes in performance at the interface. For example, in the present application, the hardness gradient of the lower plug from the surface to the core is: surface layer 11 (100% ceramic, high wear resistance) → gradient transition layer 12 (ceramic + metal composite material) → base layer 13 (100% metal, high toughness), and the hardness gradually decreases to form a gradient change.

[0029] Thus, a lower pressure rod assembly is provided, wherein the lower pressure rod plug 1 is a solid structure, and the lower pressure rod plug 1 includes a surface layer 11, a gradient transition layer 12 and a base layer 13 from the outside to the inside, wherein the surface layer 11, the gradient transition layer 12 and the base layer 13 form a gradient structure in sequence, wherein the surface layer 11 is made of a high-hardness ceramic material, the gradient transition layer 12 is made of a metal-ceramic composite material, and the base layer 13 is made of a Cr-Mo alloy steel material. The high-hardness layer of the surface layer 11 is beneficial for reducing wear, and the base layer 13 is a toughness layer, which avoids the overall brittle fracture and bursting of the lower pressure rod plug 1, thereby increasing the service life of the lower pressure rod plug 1 by more than 30%, and the gradient structure of the lower pressure rod plug can effectively disperse stress, and the surface layer 11 is made of a high-hardness ceramic material, which can reduce powder adhesion and improve the surface finish of the molded part.

[0030] In one embodiment, the surface layer 11 has a laser-textured micro-pit array, and the micro-pits are filled with solid lubricants; the depth of the micro-pit array is 10 μm-30 μm.

[0031] During the long-term use of the lower pressure rod plug 1, local plastic deformation or fatigue accumulation caused by high-pressure pressing (>500MPa) can easily cause subtle microcracks on the edge or defects of the lower pressure rod plug 1. Microcracks are an important factor affecting service life and molding quality.

[0032] The present application uses a laser-textured micro-pit array in the surface layer 11. The micro-pits have a diameter of 20μm-100μm and a depth of 10μm-30μm. The micro-pits act as physical barriers, forcing the crack propagation path to change. When the crack encounters the pits, it needs to detour or branch, consuming more energy. The pit structure increases the surface area of ​​the crack, which requires more energy to continue to expand. The pits make the contact pressure distribution more even, avoiding local excessive wear, and can effectively reduce the probability of cracks.

[0033] The pits can store solid lubricants (such as MoS2 and graphite) to form a self-lubricating film, reduce frictional heat, and reduce the risk of thermal stress cracks. The micro-pit array significantly improves the anti-microcrack performance through the triple mechanisms of stress dispersion, crack deflection, and lubrication enhancement.

[0034] In one embodiment, the gradient transition layer 12 is dispersed with TiC nanowires, the diameter of the TiC nanowires is 50nm-100nm, and the aspect ratio is greater than 20.

[0035] In this way, TiC nanowires have high modulus (~450GPa) and high strength (~15GPa), which can effectively hinder crack propagation. When cracks encounter nanowires, they are forced to detour or branch, consuming energy. When nanowires cross cracks, they delay fracture through bridging effect.

[0036] In one embodiment, the lower pressing rod assembly further includes a plug pad 5 , and the plug pad 5 is sleeved on the lower pressing rod plug 1 and abuts against the inner layer of the lower pressing rod 4 .

[0037] In this way, the plug pad 5 can be made of soft material, which can effectively alleviate the hard contact between the lower pressing rod plug 1 and the lower pressing rod 4 when the lower pressing rod plug 1 presses the metal powder.

[0038] In one embodiment, the surface layer 11 has an Al2O3-Y2O3 composite coating; the Al2O3-Y2O3 composite coating is clad on the micro-pit array of the surface layer by laser; the depth of the micro-pits is 10%-15% of the thickness of the Al2O3-Y2O3 composite coating.

[0039] Al2O3-Y2O3 composite coating is a high-performance ceramic coating, mainly composed of Al2O3 (aluminum oxide), Y2O3 (yttrium oxide), and other additives. Al2O3 (aluminum oxide) provides ultra-high hardness, and Y2O3 in Y2O3 3+ Ions fill Al2O3 grain boundary vacancies, inhibit grain boundary diffusion, reduce high-temperature grain coarsening, and improve grain boundary fracture toughness.

[0040] In this way, the Al2O3-Y2O3 composite coating is clad on the micro-pit array of the surface layer by laser, and the Al2O3-Y2O3 composite coating can provide a basic wear-resistant / heat-resistant layer. The presence of micro-pits can enhance the bonding strength of the Al2O3-Y2O3 composite coating and store lubricants. The pit structure can relieve the internal stress of the Al2O3-Y2O3 composite coating. At the same time, the grain boundary strengthening effect of Y2O3 can prevent the initiation of micro-cracks at the edge of the pits, making the lower pressure rod plug 1 stronger. The pits can be designed for non-uniform distribution, for example, the pit density in the high-pressure area is increased by 20%.

[0041] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A push rod assembly, characterized in that: It includes a lower pressure rod plug, a screw, a lower pressure rod sleeve, and a lower pressure rod; The screw is threadedly connected with the lower pressure rod plug, the lower pressure rod shaft sleeve is sleeved on the screw, the lower pressure rod is sleeved on the lower pressure rod shaft sleeve and the lower pressure rod plug in sequence, the top of the screw has a mounting hole, and the two sides of the lower pressure rod have notches, and the mounting piece passes through the mounting hole and the two ends are clamped in the notches; The lower pressure rod plug has a solid structure, and includes a surface layer, a gradient transition layer and a base layer from the outside to the inside. The surface layer, the gradient transition layer and the base layer form a gradient structure. The surface layer is made of a high-hardness ceramic material, the gradient transition layer is made of a metal-ceramic composite material, and the base layer is made of a Cr-Mo alloy steel material.

2. A push rod assembly according to claim 1, characterized in that: The high-hardness ceramic material is one of aluminum oxide and silicon carbide.

3. The push rod assembly according to claim 1, characterized in that: The metal-ceramic composite material is a gradient mixture of WC-Co and steel.

4. The push rod assembly according to claim 1, characterized in that: The surface layer has a laser-textured micro-pit array, and the micro-pits are filled with solid lubricants.

5. A push rod assembly according to claim 4, characterized in that: The depth of the micro-pit array is 10 μm-30 μm.

6. The push rod assembly according to claim 1, characterized in that: The gradient transition layer is dispersed with TiC nanowires, the diameter of the TiC nanowires is 50nm-100nm, and the aspect ratio is greater than 20.

7. The push rod assembly according to claim 1, characterized in that: The lower pressing rod assembly also includes a plug pad, which is sleeved on the lower pressing rod plug and abuts against the inner layer of the lower pressing rod.

8. The push rod assembly according to claim 4, characterized in that: The surface layer is provided with an Al2O3-Y2O3 composite coating.

9. The push rod assembly according to claim 5, characterized in that: The Al2O3-Y2O3 composite coating is clad on the micro-pit array of the surface layer by laser melting.

10. The push rod assembly according to claim 4, characterized in that: The depth of the micro-pits is 10%-15% of the thickness of the Al2O3-Y2O3 composite coating.

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