Metal powder injection molding die

Abstract

The utility model discloses a metal powder injection molding mold. The metal powder injection molding mold comprises a mold main body, an aluminum mold core and a positioning pin, the mold main body is provided with a mold cavity, and the aluminum mold core is fixed in the mold cavity through a positioning pin; a nitriding layer and a first molybdenum disulfide coating are sequentially arranged on the inner wall of a mold cavity of the mold body. The outer surface of the aluminum mold core is covered with a second molybdenum disulfide coating, and at least part of the interior of the aluminum mold core is of a hollow structure. Molybdenum disulfide coatings are formed on the inner wall of the mold cavity and the outer portion of the aluminum mold core, friction resistance in the metal powder injection molding process can be reduced, and MIM injection molding of a metal piece with an inner cavity is facilitated. The aluminum profile adopts a hollow structure and can be subsequently soaked and removed by sodium hydroxide, and the removal efficiency is improved; the method is suitable for preparing metal parts with complex structures and high in product precision.

Description

Technical Field

[0001] The utility model belongs to the technical field of metal forming, and in particular relates to a metal powder injection molding die. Background Art

[0002] Metal Powder Injection Molding (MIM) is an advanced manufacturing process that combines powder metallurgy and plastic injection molding. It is suitable for producing small, complex-shaped metal parts and is commonly used in a variety of fields, including electronics, the automotive industry, and hardware. Metal powder is injected into the MIM process to create metal parts with internal cavities, such as faucets. In particular, complex, special-shaped faucets require a core to form the faucet's internal structure.

[0003] Existing cores include high-strength salt cores, plastic cores, etc. Among them, high-strength salt cores (the main component is sodium chloride) are suitable for gravity casting, low-pressure casting and high-pressure casting of aluminum-magnesium alloys. They are easy to collapse and remove when soaked in high-pressure water guns or hot water. However, the strength of the salt core is relatively low and cannot withstand the pressure during the MIM injection molding process of titanium alloys. It is prone to cracking or even collapse during the mold closing and even molding process. If plastic cores such as POM are used, the POM and other plastic cores will expand and deform due to heat during the mold heating process, blocking the powder injection molding channel, resulting in incomplete molding. The above problems limit the manufacture of faucets with complex structures. Utility Model Content

[0004] The utility model aims to solve the deficiencies in the prior art and provides a metal powder injection molding die.

[0005] In order to achieve the above objectives, the technical solution of the utility model is:

[0006] A metal powder injection molding mold comprises a mold body, an aluminum core and a locating pin; the mold body has a mold cavity, and the aluminum core is fixed in the mold cavity by the locating pin; the inner wall of the mold cavity of the mold body is sequentially provided with a nitriding layer and a first molybdenum disulfide coating; the outer surface of the aluminum core is covered with a second molybdenum disulfide coating, and the interior is at least partially hollow.

[0007] Optionally, the material of the mold body is H13 steel, P20 steel, 718 steel or 420 steel.

[0008] Optionally, the thickness of the nitriding layer is 50-200 μm.

[0009] Optionally, the thickness of the first molybdenum disulfide coating is 50-100 μm.

[0010] Optionally, the material of the aluminum core is 6061 aluminum alloy, 6063 aluminum alloy or AlSi10Mg aluminum alloy.

[0011] Optionally, the thickness of the second molybdenum disulfide coating is 50-100 μm.

[0012] Optionally, the wall thickness of the hollow structure of the aluminum core is less than 1 mm.

[0013] Optionally, the mold body comprises a first mold and a second mold, the first mold and the second mold enclose the mold cavity, and the aluminum core cooperates with the mold cavity to form a forming space of the metal piece with the inner cavity.

[0014] Optionally, the positioning pin is fitted in the hollow structure of the aluminum core and extends outward.

[0015] Optionally, the aluminum core comprises a first forming part and a second forming part, the first forming part is used for forming a water outlet area of the faucet valve body, the second forming part is used for forming a water inlet to valve port area of the faucet valve body, and the first forming part and the second forming part are hollow structures; the positioning pin comprises a first positioning pin and a second positioning pin, the first positioning pin is fitted in the first forming part, and the second positioning pin is fitted in the second forming part.

[0016] The beneficial effects of the utility model are as follows:

[0017] The molybdenum disulfide coating is formed on the inner wall of the mold cavity and the outer portion of the aluminum core, so that the frictional resistance in the metal powder injection molding process is reduced, the MIM injection molding of the metal piece with the inner cavity is facilitated, the aluminum profile adopts the hollow structure, and the subsequent sodium hydroxide soaking can be used for removal and improvement of the removal efficiency; the utility model is suitable for preparing the metal piece with the complex structure and has high product precision. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a disassembled structure schematic view of the metal powder injection molding faucet valve body mold of the embodiment;

[0019] Figure 2 It is a schematic view of the faucet valve body by the metal powder injection molding in the mold of the embodiment;

[0020] Figure 3 It is a structure schematic view of the first mold of the embodiment;

[0021] Figure 4 It is a mold cavity inner wall local section schematic view of the first mold of the embodiment;

[0022] Figure 5 It is a structure schematic view of the aluminum core and the positioning pin combination of the embodiment;

[0023] Figure 6 A cross-sectional view of an embodiment of the aluminum core and positioning pin combination. DETAILED DESCRIPTION

[0024] The utility model will be further explained in connection with the drawings and specific embodiments. The drawings of the utility model are only schematic to make it easier to understand the utility model, and the specific proportion can be adjusted according to design requirements. The relative position of the components in the figures described in the specification and the definition of the front / back surface should be understood by those skilled in the art as referring to the relative position of the components, so they can be reversed to show the same components, which should be included in the scope disclosed in the specification.

[0025] The metal powder injection molding die of the embodiment is used for the molding of metal pieces with internal cavities, for example, faucet valve bodies, as shown in Figure 1 and Figure 2 , which comprises a die body 1, an aluminum core 2 and a positioning pin 3; the die body 1 comprises a first die 11 and a second die 12, which enclose a die cavity a, the aluminum core 2 is fixed in the die cavity a by the positioning pin 3, and the aluminum core 2 cooperates with the die cavity a to form a molding space of the faucet valve body 4. The die is placed between the base and the upper cover of the metal powder injection molding equipment, for example, the die body 1 and the positioning pin are fixed on the base, the solid metal powder is uniformly mixed with the organic binder, and after granulation, it is injected into the molding space in the die cavity a in a heated and plasticized state (~150℃) by the injection molding equipment to solidify and form the faucet valve body 4 for manufacturing. The metal powder is, for example, pure titanium or titanium alloy.

[0026] The material of the die body 1 is H13 steel, P20 steel, 718 steel or 420 steel. Referring to Figure 3 and Figure 4 , the die body is used to form the wall surface of the outer surface of the faucet valve body, that is, the inner wall of the die cavity a, for example, the first die 11, which has a nitriding layer 5 and a first molybdenum disulfide coating 6 in sequence on the inner wall a1 of the die cavity. Carburizing refers to the process of allowing carbon atoms to penetrate into the surface layer of steel. It is also to make the workpiece of low carbon steel have a surface layer of high carbon steel, and then quenching and low temperature tempering, so that the surface layer of the workpiece has high hardness and wear resistance, while the center part of the workpiece still maintains the toughness and plasticity of low carbon steel. The thickness of the nitriding layer 5 is 50-200μm, for example, 100μm, 150μm, etc. or any value therebetween. The thickness of the first molybdenum disulfide coating 6 is 50-100μm, for example, 70μm, 90μm, etc. or any value therebetween. The first molybdenum disulfide coating 6 forms a lubricating film between the friction interface between the inner wall of the die cavity of the die body and the outer surface of the powder molded body, effectively reducing the friction coefficient. The second die 12 has the same setting.

[0027] The material of the aluminum core 2 is 6061 aluminum alloy, 6063 aluminum alloy or AlSi10Mg aluminum alloy. The aluminum core 2 is used to form the wall surface of the inner surface of the faucet valve body, that is, the outer wall of the aluminum core 2 is entirely covered with a second molybdenum disulfide coating 7, and the thickness of the second molybdenum disulfide coating 7 is 50-100 μm, such as 70 μm, 90 μm, etc. or any value therebetween. The second molybdenum disulfide coating 7 forms a lubricating film between the friction interface between the outer surface of the aluminum core 2 and the inner surface of the powder molded body, effectively reducing the friction coefficient. Faucets are large in size and metal powder injection molding is relatively difficult. By coating the inner wall of the mold cavity of the mold body and the outer surface of the aluminum core with a molybdenum disulfide coating, the friction resistance during the metal powder injection molding process can be reduced, which is beneficial to the MIM injection molding of the faucet.

[0028] The interior of the aluminum core 2 is at least partially hollow, which is beneficial to the efficiency of its subsequent removal. Figure 5 and Figure 6 The aluminum core 2 includes a first molded portion 21 and a second molded portion 22, wherein the first molded portion 21 is used to form the water outlet area of ​​the faucet valve body, and the second molded portion 22 is used to form the water inlet to valve port area of ​​the faucet valve body. In one embodiment, the first molded portion 21 and the second molded portion 22 are hollow structures, such as hollow annular wall structures, with a wall thickness of less than 1 mm, such as 500 μm, 800 μm, or any value therebetween. The first locating pin 3a fits into the hollow structure of the first molded portion 21 and extends outward, and the second locating pin 3b fits into the hollow structure of the second molded portion 22, passes through the water inlet to the valve port, and extends outward. The portion located in the hollow structure matches the shape of the hollow structure to provide support, and the portion extending outward is used for positioning and fixing during the MIM molding process. The aluminum core 2 is manufactured using processes such as machining-welding or metal 3D printing, and can be directly formed on the locating pin, and the area covering the locating pin forms a hollow structure. In other embodiments, the range and location of the hollow structure can be varied, but it is preferably located in an area of ​​greater thickness. The aforementioned aluminum core provides high strength, making it less susceptible to cracking, deformation, or collapse during the MIM molding process. Furthermore, it can be removed efficiently through methods such as sodium hydroxide soaking, without causing corrosion damage to the pure titanium or titanium alloy faucet body. Furthermore, compared to traditional core-pulling mechanisms, aluminum cores can be used to create faucets with more complex structures, such as special-shaped faucets, extending their applicability.

[0029] When the faucet valve body is manufactured using the aforementioned metal powder injection molding die, the faucet valve body blank is obtained after injection molding, which is wrapped around an aluminum core. The aluminum core is then subjected to processes such as removal, degreasing, and high-temperature sintering. The aluminum core is removed, for example, by soaking in sodium hydroxide at room temperature, with a concentration of 5%-20% for 12-24 hours. The degreasing process utilizes a combination of nitric acid atmosphere degreasing and high-temperature degreasing, with the nitric acid atmosphere degreasing process being (120°C, 2 hours) and the vacuum heat degreasing process being (150°C, 10 hours). The sintering process is (1300°C, 30 hours).

[0030] The above embodiments are only used to further illustrate a metal powder injection molding die of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the technical solution of the present invention.

Claims

1. A metal powder injection molding die, characterized in that: The invention comprises a mold body, an aluminum core and a positioning pin; the mold body has a mold cavity, and the aluminum core is fixed in the mold cavity by the positioning pin; the inner wall of the mold cavity of the mold body is sequentially provided with a nitriding layer and a first molybdenum disulfide coating; the outer surface of the aluminum core is covered with a second molybdenum disulfide coating, and the interior is at least partially hollow.

2. The metal powder injection molding die according to claim 1, characterized in that: The material of the mold body is H13 steel, P20 steel, 718 steel or 420 steel.

3. The metal powder injection molding die according to claim 1, characterized in that: The thickness of the nitriding layer is 50-200 μm.

4. The metal powder injection molding die according to claim 1, characterized in that: The thickness of the first molybdenum disulfide coating is 50-100 μm.

5. The metal powder injection molding die according to claim 1, characterized in that: The material of the aluminum core is 6061 aluminum alloy, 6063 aluminum alloy or AlSi10Mg aluminum alloy.

6. The metal powder injection molding die according to claim 1, characterized in that: The thickness of the second molybdenum disulfide coating is 50-100 μm.

7. The metal powder injection molding die according to claim 1, characterized in that: The wall thickness of the hollow structure of the aluminum core is less than 1 mm.

8. The metal powder injection molding die according to claim 1, characterized in that: The mold body includes a first mold and a second mold. The first mold and the second mold are enclosed to form the mold cavity. The aluminum core cooperates with the mold cavity to form a molding space for the metal part with an inner cavity.

9. The metal powder injection molding die according to claim 1, characterized in that: The positioning pin is fitted into the hollow structure of the aluminum core and extends outward.

10. The metal powder injection molding die according to claim 9, characterized in that: The mold is a forming mold for the faucet valve body, and the aluminum core includes a first forming part and a second forming part, wherein the first forming part is used to form the water outlet area of ​​the faucet valve body, and the second forming part is used to form the water inlet to valve port area of ​​the faucet valve body, and the first forming part and the second forming part are hollow structures; the positioning pin includes a first positioning pin and a second positioning pin, the first positioning pin is fitted in the first forming part, and the second positioning pin is fitted in the second forming part.

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