Metal injection mechanism and injection molding machine

Abstract

The utility model discloses a metal injection mechanism and an injection molding machine, the metal injection mechanism comprises a charging barrel with an internal channel, a feeding unit and a nozzle unit connected to one end of the charging barrel, and the feeding unit is used for feeding slurry in the charging barrel into the nozzle unit and enabling the slurry to flow out; the nozzle unit is provided with a temperature control unit, the temperature control unit is used for controlling the nozzle unit to have a first temperature, so that slurry flowing into the nozzle unit before injection is solidified to form a cold plug, or the temperature control unit is used for controlling the nozzle unit to have a second temperature, so that the cold plug is melted during injection. The utility model has the beneficial effects that the leakage risk of slurry before injection can be avoided, and the product quality is ensured.

Description

Technical Field

[0001] This utility model relates to the technical field of metal injection molding equipment, and in particular to a metal injection mechanism and injection molding machine. Background Technology

[0002] Metal injection molding technology offers advantages such as the ability to mold complex metal parts in a single step, low scrap rate, high production efficiency, and ease of automation. It is widely used in the fabrication of small, complex-shaped metal parts. Based on the raw material form, metal injection molding technology can be categorized into liquid metal injection molding, powder metallurgy injection molding, and semi-solid metal injection molding. Semi-solid magnesium alloy products are primarily manufactured using semi-solid metal injection molding in conjunction with molds. Compared to other casting methods, semi-solid magnesium alloy injection molding offers the following advantages: 1. Energy saving: lower melting temperature of magnesium alloys. While general magnesium alloy casting requires heating the alloy to 650-680℃, injection molding only requires heating to 580-600℃. 2. Environmental friendliness: no protective gas required. In general magnesium alloy casting, molten magnesium alloy requires the use of environmentally harmful protective gases such as SF6 to prevent oxidation and combustion. In injection molding, the molten magnesium alloy does not come into contact with air.

[0003] Chinese utility model patent with patent publication number CN116493567A and publication date of July 28, 2023 discloses a semi-solid magnesium alloy two-stage injection device, including a horizontally arranged feed cylinder assembly and an inclined feed cylinder assembly. The feed cylinder assembly and the feed cylinder assembly respectively form a lower channel and an upper channel. The tail end of the upper channel is connected to the lower channel, and the front end of the upper channel is provided with a first feed port. A backflow prevention mechanism is also provided at the connection between the lower channel and the upper channel. The semi-solid magnesium alloy two-stage injection device disclosed in this Chinese utility model patent has the following general usage method and advantages: Semi-solid magnesium alloy slurry is introduced into the upper channel through the first feed port. The rotation of the second screw is controlled by the second drive mechanism, which melts the semi-solid magnesium alloy slurry in the upper channel of the second screw, greatly improving the melting capacity and injection volume of the magnesium alloy slurry. The molten slurry is then transferred to the feeding section of the lower channel and combined with the slurry introduced through the second feed port. The slurry is further melted and transported to the injection section through the rotation and linear motion of the first screw, and then injected into the molding process through the injection head. This improves the injection response and injection speed, and greatly increases the working efficiency of semi-solid magnesium alloy injection molding.

[0004] However, since the material preparation time is generally long and the slurry needs to be mixed in the feed cylinder assembly before injection, the residence time of the slurry in the lower channel is increased. This causes some slurry to flow into the injection head and enter the mold under pressure in advance. This part of the slurry may solidify prematurely due to the decrease in temperature, resulting in the slurry not being able to completely fill the mold cavity during the actual injection, which affects the product quality. Utility Model Content

[0005] The purpose of this invention is to provide a metal injection mechanism that can avoid the risk of material leakage before injection and ensure product quality.

[0006] This utility model is achieved through the following technical solution.

[0007] A metal injection mechanism includes a barrel with an internal channel, a feeding unit, and a nozzle unit connected to one end of the barrel. The feeding unit is used to feed slurry from the barrel into the nozzle unit and allow it to flow out. The nozzle unit is provided with a temperature control unit, which is used to control the nozzle unit to have a first temperature, such that the slurry flowing into the nozzle unit before injection solidifies to form a cold plug, or the temperature control unit is used to control the nozzle unit to have a second temperature, such that the cold plug melts during injection.

[0008] As a further improvement of this utility model, the nozzle unit includes at least a first nozzle tube section disposed at the front end of the barrel, one end of the first nozzle tube section is connected to the inside of the barrel and the other end is provided with a first outlet, and the temperature control unit is at least partially disposed on the first nozzle tube section.

[0009] As a further improvement of this utility model, the nozzle unit further includes a second nozzle tube section, which is connected to the first outlet. The second nozzle tube section is provided with a second outlet and an air inlet that faces the second outlet and is used to protect the gas injection. The temperature control unit is at least partially disposed on the second nozzle tube section.

[0010] As a further improvement of this utility model, the first nozzle pipe section is connected to the side of the second nozzle pipe section, and the protective gas is transported through the first outlet in the second nozzle pipe section.

[0011] As a further improvement of this utility model, a connecting pipe section is provided at one end of the first nozzle pipe section near the material cylinder. The connecting pipe section is embedded in the material cylinder and communicates with the interior of the material cylinder. The inner diameter of the connecting pipe section is larger than the inner diameter of the first nozzle pipe section.

[0012] As a further improvement of this utility model, the first nozzle tube segment is bent and extended.

[0013] As a further improvement of this utility model, the material cylinder is provided with a feed inlet, which is connected to the internal channel of the material cylinder.

[0014] As a further improvement of this utility model, the internal channel of the barrel includes an injection section and a feeding section that are interconnected. The feeding unit includes a screw disposed in the barrel and a drive assembly for controlling the screw to rotate and move linearly. The feeding section is formed inside the screw. The injection section is connected to the nozzle unit. The feed port is connected to the feeding section.

[0015] As a further improvement of this utility model, the temperature control unit includes multiple heating coils.

[0016] A metal injection molding machine includes a metal injection mechanism as described in the above technical solution.

[0017] The beneficial effects of this utility model are:

[0018] The nozzle unit is equipped with a temperature control unit, which maintains either a first temperature or a second temperature. Before injection, under the control of the temperature control unit, the slurry flowing into the nozzle unit solidifies inside, forming a high-solids cold plug that blocks the nozzle unit. This prevents the slurry in the barrel from being injected into the mold, naturally isolating the connection between the mold and the barrel. This ensures that the slurry is stored in the barrel before injection, avoiding the risk of leakage and guaranteeing the quality of the final product. Simultaneously, during injection, the temperature control unit maintains a second temperature on the nozzle unit, causing the cold plug to melt and cooperating with the feeding unit to complete the injection operation. Attached Figure Description

[0019] The preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings to help understand the purpose and advantages of this utility model, wherein:

[0020] Figure 1 This is a schematic diagram of the structure of a metal injection molding machine according to the present invention;

[0021] Figure 2 This is an internal structural diagram of a metal injection mechanism according to the present invention;

[0022] Figure 3 This is a schematic diagram of the nozzle unit. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0025] Example 1:

[0026] A metal injection mechanism, as described above Figures 1-3 The device includes a barrel 1 with an internal channel, a feeding unit 2, and a nozzle unit 3 connected to one end of the barrel 1. The nozzle unit 3 communicates with the internal channel of the barrel 1. The feeding unit 2 is used to feed the molten metal slurry located in the internal channel into the nozzle unit 3. The feeding unit 2 includes a screw 21 located in the barrel 1 and a drive assembly 22 for controlling the rotation and linear motion of the screw 21. The nozzle unit 3 is provided with a temperature control unit 4. The temperature control unit 4 is used to control the nozzle unit 3 to have a first temperature, so that the slurry flowing into the nozzle unit 3 before injection solidifies to form a cold plug, or the temperature control unit 4 is used to control the nozzle unit 3 to have a second temperature, so that the cold plug melts during injection.

[0027] It should be noted that the specific structure of the feeding unit 2 here can be the structure of the pressing unit in the applicant's earlier Chinese patent publication number CN114472844A.

[0028] In this embodiment, it should be noted that the first temperature is the temperature at which the metal slurry solidifies, and the second temperature is the temperature at which the metal slurry is in a molten state. Before injection, under the action of the temperature control unit 4, the slurry flowing into the nozzle unit 3 solidifies inside the nozzle unit 3, forming a cold plug with a high solids content that blocks the nozzle unit 3. This prevents the slurry in the barrel 1 from being injected into the mold through the nozzle unit 3, naturally isolating the connection between the mold and the barrel 1. This ensures that the slurry is stored in the barrel 1 before injection, avoiding the risk of leakage before injection and ensuring the quality of the final molded product. At the same time, during injection, the temperature control unit 4 controls the nozzle unit 3 to have a second temperature, causing the cold plug to melt, which, together with the feeding unit 2, completes the injection operation.

[0029] Specifically, the nozzle unit 3 includes at least a first nozzle section 31 located at the front end of the barrel 1. One end of the first nozzle section 31 is connected to the interior of the barrel 1, and the other end has a first outlet 311. The temperature control unit 4 is at least partially located on the first nozzle section 31, thus a cold plug can be formed on the first nozzle section 31. Furthermore, a connecting pipe section 34 is located at the end of the first nozzle section 31 closest to the barrel 1. The connecting pipe section 34 is embedded inside the barrel 1 and communicates with the interior of the barrel 1. The inner diameter of the connecting pipe section 34 is larger than the inner diameter of the first nozzle section 31. When the slurry enters the first nozzle section 31 from the connecting pipe section 34, the slurry flow path becomes smaller, thus increasing the flow resistance and reducing the flow velocity. This makes it easier for the slurry to remain within the first nozzle section 31, reducing the risk of the slurry flowing out of the first nozzle section 31 at this time.

[0030] In this embodiment, in order to prevent the cold plug in the first nozzle tube section 31 from being dislodged from the first nozzle tube section 31 by the pressure inside the barrel 1, the first nozzle tube section 31 is configured to be curved and extended. When the cold plug in the first nozzle tube section 31 is subjected to the pressure inside the barrel 1, the curved tube section can generate resistance to the cold plug, thereby preventing the cold plug from moving in the first nozzle tube section 31, thereby improving the stability of the cold plug.

[0031] In this embodiment, the nozzle unit 3 further includes a second nozzle section 32, which is connected to the first outlet 311. The second nozzle section 32 is provided with a second outlet 321, which is used to inject the slurry in the nozzle into the mold. The second nozzle section 32 is also provided with an air inlet facing the second outlet 321 for injecting protective gas. The temperature control unit 4 is at least partially disposed on the second nozzle section 32. The temperature control unit 4 can heat the protective gas and slurry in the second nozzle section 32 to keep the slurry in a molten state. The protective gas can be an inert gas such as argon or helium. The protective gas prevents the slurry from contacting the air in the mold and oxidizing to form oxides when it enters the mold. On the other hand, the protective gas has a certain thrust, which can push the slurry in the second nozzle section 32 out of the second outlet 321, thereby preventing the slurry from remaining in the second nozzle section 32 and ensuring the quality of the molded product.

[0032] In this embodiment, the first nozzle section 31 is connected to the side of the second nozzle section 32. The second outlet 321 and the air inlet 33 are respectively formed at both ends of the second nozzle section 32. Specifically, the air inlet 33 is located at the upper end of the second nozzle section 32, and the second outlet 321 is located at the lower end of the second nozzle section 32. At this time, the protective gas is transported through the first outlet 311 within the second nozzle section 32. It should be noted that when the slurry injection is completed, the temperature control unit 4 stops working. At this time, it is necessary to wait for the temperature of the first nozzle section 31 to drop to a certain level until a cold plug can be formed before the next slurry preparation can be carried out. This process greatly reduces the production efficiency. Therefore, protective gas can be continuously input into the second nozzle section 32, that is, some protective gas can enter the first nozzle section 31. When the protective gas flows through the first nozzle section 31, it can carry away the heat of the first nozzle section 31, thereby playing a role in rapidly cooling the first nozzle section 31 and greatly improving the production efficiency.

[0033] In this embodiment, the temperature control unit 4 includes multiple heating coils and a controller. The heating coils can be of electromagnetic induction or resistance wire structure. Heating coils are provided on the outside of the first nozzle section 31 and the second nozzle section 32, so that heating of the first nozzle section 31 and the second nozzle section 32 can be realized.

[0034] In this embodiment, the barrel 1 is provided with a feed port 11, which is connected to the internal channel of the barrel 1. Therefore, the semi-solid metal slurry can enter the internal channel of the barrel 1 through the feed port 11. The internal channel of the barrel 1 includes an injection section 12 and a feeding section 13, which are connected through each other. The feeding section 13 is formed inside the screw 21. The injection section 12 is connected to the nozzle unit 3. The feed port 11 is connected to the feeding section 13 and is used to receive the semi-solid metal slurry input through the feed port 11. During operation, the drive assembly 22 controls the rotation and linear motion of the screw 21 to further melt the semi-solid metal slurry located in the feeding section 13 and transport it to the injection section 12. Then, it is injected into the mold through the nozzle unit 3 for injection molding.

[0035] Example 2:

[0036] A metal injection molding machine includes a metal injection mechanism as described in Example 1.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A metal injection mechanism characterized by, The device includes a barrel (1) with an internal channel, a feeding unit (2), and a nozzle unit (3) connected to one end of the barrel (1). The nozzle unit (3) communicates with the internal channel of the barrel (1). The feeding unit (2) is used to feed the slurry in the barrel (1) into the nozzle unit (3) and allow it to flow out. The nozzle unit (3) is provided with a temperature control unit (4). The temperature control unit (4) is used to control the nozzle unit (3) to have a first temperature, so that the slurry flowing into the nozzle unit (3) before injection solidifies to form a cold plug, or the temperature control unit (4) is used to control the nozzle unit (3) to have a second temperature, so that the cold plug melts during injection. The nozzle unit (3) includes at least a first nozzle tube section (31) located at the front end of the barrel (1). One end of the first nozzle tube section (31) is connected to the interior of the barrel (1), and the other end is provided with a first outlet (311). The temperature control unit (4) is at least partially located on the first nozzle tube section (31). The nozzle unit (3) also includes a second nozzle tube section (32). The second nozzle tube section (32) is connected to the first outlet (311). The second nozzle tube section (32) is provided with a second outlet (321) and an air inlet facing the second outlet (321) for injecting protective gas. The temperature control unit (4) is at least partially located on the second nozzle tube section (32). The first nozzle tube section (31) is connected to the side of the second nozzle tube section (32), and the protective gas is transported through the first outlet (311) in the second nozzle tube section (32). When the first nozzle section switches from the second temperature to the first temperature, the protective gas in the second nozzle section (32) enters the first nozzle section (31) through the first outlet (311) to reduce the temperature of the first nozzle section (31).

2. A metal injection molding apparatus as defined in claim 1, wherein The first nozzle section (31) has a connecting pipe section (34) at one end near the material cylinder (1). The connecting pipe section (34) is embedded in the material cylinder (1) and communicates with the interior of the material cylinder (1). The inner diameter of the connecting pipe section (34) is larger than the inner diameter of the first nozzle section (31).

3. A metal injection molding apparatus as defined in claim 1, wherein The first nozzle tube segment (31) is bent and extended.

4. A metal injection molding apparatus as defined in claim 1, wherein The feed cylinder (1) is provided with a feed inlet (11), which is connected to the internal channel of the feed cylinder (1).

5. A metal injection molding apparatus as defined in claim 4, wherein, The internal channel of the barrel (1) includes an injection section (12) and a feeding section (13) that are interconnected. The feeding unit (2) includes a screw (21) disposed in the barrel (1) and a drive assembly (22) for controlling the screw (21) to rotate and move linearly. The feeding section (13) is formed in the screw (21). The injection section (12) is connected to the nozzle unit (3). The feed port (11) is connected to the feeding section (13).

6. A metal injection molding machine according to any one of claims 1 to 5, wherein, The temperature control unit (4) includes multiple heating coils.

7. A metal injection molding machine characterized by, A metal injection molding machine comprising any one of claims 1-6.

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