Metal injection mechanism and injection molding machine

Abstract

The invention 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 injection mold has the beneficial effects that the leakage risk of slurry before injection can be avoided, and the product quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of metal injection molding devices, in particular to a metal injection mechanism and an injection molding machine. Background Art

[0002] Metal injection molding technology has the advantages of being able to mold complex-shaped metal parts in one go, low scrap rate, high production efficiency, and easy automation. It is widely used in the preparation of small complex-shaped metal parts. Metal injection molding technology can be divided into liquid metal injection molding technology, powder metallurgy injection molding technology, and semi-solid metal injection molding technology according to the form of raw materials. Semi-solid magnesium alloy products are mainly produced using semi-solid metal injection molding technology in conjunction with molds. Compared with other casting methods, semi-solid magnesium alloy injection molding has the following advantages: First, energy saving, low melting temperature of magnesium alloy: general magnesium alloy casting requires heating the magnesium alloy to 650-680℃, while injection molding magnesium alloy only needs to be heated to 580-600℃; second, environmental protection, no protective gas is required. General magnesium alloy casting requires the use of SF6 and other environmentally harmful protective gases to prevent oxidation and combustion of magnesium alloy after melting the magnesium alloy to prevent oxidation and combustion of magnesium alloy. The melted magnesium alloy in injection molding does not come into contact with air.

[0003] A Chinese invention patent with patent announcement number CN116493567A and announcement date 2023.7.28 discloses a semi-solid magnesium alloy two-stage injection device, including a horizontally arranged lower barrel assembly and an inclined upper barrel assembly, wherein the lower barrel assembly and the upper barrel assembly are respectively formed with a lower channel and an upper channel, the tail end of the upper channel is connected to the lower channel, and a first feed port is provided at the front end of the upper channel, and a non-return mechanism is also provided at the connection between the lower channel and the upper channel. The Chinese invention patent discloses a semi-solid magnesium alloy two-stage injection device, and its general usage and advantages are as follows: semi-solid magnesium alloy slurry is introduced into the upper channel through the first feed port, and the rotational movement of the second screw is controlled by the second drive mechanism to melt the semi-solid magnesium alloy slurry in the upper channel of the second screw, thereby greatly improving the melting capacity and injection volume of the magnesium alloy slurry. The melted slurry is transmitted 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 shooting section through the rotation and linear movement of the first screw for injection molding through the injection head, thereby improving the injection response and injection speed, and greatly improving the work efficiency of semi-solid magnesium alloy injection molding.

[0004] However, since the material preparation time is generally long and this device needs to mix the slurry in the lower barrel assembly before slurry injection, the residence time of the slurry in the lower channel is increased, so that part of the slurry may flow into the injection head and enter the mold in advance under the action of pressure. This part of the slurry may solidify prematurely due to the decrease in temperature, resulting in the slurry being unable to completely fill the mold cavity during formal injection, affecting product quality. Summary of the invention

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

[0006] The present invention is achieved through the following technical solutions.

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

[0008] As a further improvement of the present invention, the nozzle unit includes at least a first nozzle pipe section arranged at the front end of the barrel, one end of the first nozzle pipe section is connected to the interior of the barrel and the other end is provided with a first outlet, and the temperature control unit is at least partially arranged on the first nozzle pipe section.

[0009] As a further improvement of the present invention, the nozzle unit also includes a second nozzle pipe segment, which is connected to the first outlet, and is provided with a second outlet. The second nozzle pipe segment is also provided with an air inlet arranged toward the second outlet and used for injecting protective gas, and the temperature control unit is at least partially arranged on the second nozzle pipe segment.

[0010] As a further improvement of the present invention, the first nozzle pipe section is connected to a side of the second nozzle pipe section, and a conveying path of the protective gas in the second nozzle pipe section passes through the first outlet.

[0011] As a further improvement of the present invention, a connecting pipe section is provided at one end of the first nozzle pipe section close to the barrel, the connecting pipe section is embedded in the barrel and communicated with the interior of the barrel, and 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 the present invention, the first nozzle pipe section is arranged to be bent and extended.

[0013] As a further improvement of the present invention, a feed port is provided on the barrel, and the feed port is communicated with an internal channel of the barrel.

[0014] As a further improvement of the present invention, the internal channel of the barrel includes a shooting 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 in the screw, the shooting section is connected to the nozzle unit, and the feed port is connected to the feeding section.

[0015] As a further improvement of the present invention, the temperature control unit includes a plurality of heating coils.

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

[0017] Beneficial effects of the present invention: The nozzle unit is provided with a temperature control unit, so that the nozzle unit has a first temperature or a second temperature. Before injection, under the action of the temperature control unit, the slurry flowing into the nozzle unit will solidify in the nozzle unit, forming a cold plug with a high solid phase ratio to block the nozzle unit, so that the slurry in the barrel cannot be injected into the mold by the nozzle unit, and the connection between the mold and the barrel is naturally isolated, ensuring that the slurry can be stored in the barrel 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 controls the nozzle unit to have a second temperature, so that the cold plug melts, and cooperates with the feeding unit to complete the injection operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to help understand the purpose and advantages of the present invention, wherein: Figure 1 This is a schematic structural diagram of a metal injection molding machine of the present invention; Figure 2 This is an internal structure diagram of a metal injection mechanism of the present invention; Figure 3 Schematic diagram of the structure of the nozzle unit. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below based on the accompanying drawings and implementation examples.

[0020] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. The words "inside" and "outside" refer to the direction toward or away from the geometric center of a specific component, respectively. They are relative concepts, and therefore may change accordingly according to different locations and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0021] Embodiment 1: A metal injection mechanism, referring to Figures 1 to 3 , comprising a barrel 1 having an internal channel, a feeding unit 2 and a nozzle unit 3 connected to one end of the barrel 1, the nozzle unit 3 being connected to the internal channel of the barrel 1, the feeding unit 2 being used to feed the molten metal slurry in the internal channel into the nozzle unit 3, wherein the feeding unit 2 comprises a screw 21 arranged in the barrel 1 and a driving assembly 22 for controlling the screw 21 to rotate and move linearly, a temperature control unit 4 is provided on the nozzle unit 3, 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.

[0022] It should be noted that the specific structure of the feeding unit 2 here may be the structure of the pressing unit in the Chinese patent publication number CN114472844A previously applied by the applicant.

[0023] In this embodiment, it should be noted that the first temperature here is the temperature when the metal slurry solidifies, and the second temperature is the temperature when 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 will solidify in the nozzle unit 3, forming a cold plug with a high solid phase ratio to block the nozzle unit 3, so that the slurry in the barrel 1 cannot be injected into the mold by the nozzle unit 3, and naturally isolates the connection between the mold and the barrel 1, ensuring that the slurry can be 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, so that the cold plug melts, and cooperates with the feeding unit 2 to complete the injection operation.

[0024] Specifically, the nozzle unit 3 at least includes a first nozzle pipe section 31 disposed at the front end of the barrel 1, one end of the first nozzle pipe section 31 is connected to the inside of the barrel 1 and the other end is provided with a first outlet 311, and the temperature control unit 4 is at least partially disposed on the first nozzle pipe section 31, so that a cold plug can be formed on the first nozzle pipe section 31. In addition, a connecting pipe section 34 is disposed at one end of the first nozzle pipe section 31 close to the barrel 1, and the connecting pipe section 34 is embedded in the barrel 1 and communicated with the inside of the barrel 1, and the inner diameter of the connecting pipe section 34 is larger than the inner diameter of the first nozzle pipe section 31. When the slurry enters the first nozzle pipe section 31 from the connecting pipe section 34, the path of the slurry flow becomes smaller, so the flow resistance of the slurry increases, and its flow rate decreases, so that the slurry is more likely to stay in the first nozzle pipe section 31, reducing the risk of the slurry flowing out of the first nozzle pipe section 31 at this time.

[0025] In the present embodiment, in order to prevent the cold plug in the first nozzle tube segment 31 from being separated from the first nozzle tube segment 31 due to the pressure inside the barrel 1, the first nozzle tube segment 31 is bent and extended. When the cold plug in the first nozzle tube segment 31 is subjected to the pressure inside the barrel 1, the curved tube segment can generate resistance to the cold plug to prevent the cold plug from moving in the first nozzle tube segment 31, thereby improving the stability of the cold plug.

[0026] In this embodiment, the nozzle unit 3 also includes a second nozzle pipe segment 32, which is connected to the first outlet 311. The second nozzle pipe segment 32 is provided with a second outlet 321, which is used to inject the slurry in the nozzle into the mold, and the second nozzle pipe segment 32 is provided with an air inlet arranged toward the second outlet 321 and used for injecting a protective gas. The temperature control unit 4 is at least partially arranged on the second nozzle pipe segment 32. The temperature control unit 4 can heat the protective gas and slurry in the second nozzle pipe segment 32 so that the slurry remains in a molten state. The protective gas here can be an inert gas such as argon and helium. On the one hand, the protective gas can prevent the slurry from contacting with the air in the mold when entering the mold and oxidizing to form oxides. On the other hand, the protective gas has a certain thrust, which can push the slurry in the second nozzle pipe segment 32 to be discharged from the second outlet 321, thereby preventing the slurry from remaining in the second nozzle pipe segment 32 and ensuring the quality of the product after molding.

[0027] In this embodiment, the first nozzle pipe section 31 is connected to the side of the second nozzle pipe section 32, and the second outlet 321 and the air inlet 33 are respectively formed at the two ends of the second nozzle pipe section 32. Specifically, the air inlet 33 is located at the upper end of the second nozzle pipe section 32, and the second outlet 321 is located at the lower end of the second nozzle pipe section 32. At this time, the conveying path of the protective gas in the second nozzle pipe section 32 passes through the first outlet 311. It should be noted that when the injection of the slurry is completed, the temperature control unit 4 stops working. At this time, it is necessary to wait for the temperature of the first nozzle pipe section 31 to drop to a certain degree until a cold plug can be formed before the next slurry preparation can be carried out. This process greatly reduces the production efficiency. Therefore, the protective gas can be continuously input into the second nozzle pipe section 32, that is, part of the protective gas can enter the first nozzle pipe section 31. When the protective gas flows through the first nozzle pipe section 31, it can take away the heat of the first nozzle pipe section 31, thereby playing a role in rapidly cooling the first nozzle pipe section 31, so that the first nozzle pipe section 31 can be quickly cooled, which greatly improves the production efficiency.

[0028] In this embodiment, the temperature control unit 4 includes multiple heating coils and controllers, and can use heating coils with electromagnetic induction or resistance wire structures. The outside of the first nozzle pipe segment 31 and the second nozzle pipe segment 32 are both provided with heating coils, so that the first nozzle pipe segment 31 and the second nozzle pipe segment 32 can be heated.

[0029] In this embodiment, a feed port 11 is provided on the barrel 1, and the feed port 11 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, and the internal channel of the barrel 1 includes a shooting section 12 and a feeding section 13, the shooting section 12 and the feeding section 13 are through-connected, the feeding section 13 is formed in the screw 21, the shooting section 12 is connected to the nozzle unit 3, and the feed port 11 is connected to the feeding section 13 for receiving the semi-solid metal slurry input from the feed port 11. During operation, the driving component 22 controls the rotation and linear motion of the screw 21 to further melt the semi-solid metal slurry in the feeding section 13 and transport it to the shooting section 12, and then injects it into the mold through the nozzle unit 3 for injection molding.

[0030] Embodiment 2: A metal injection molding machine includes a metal injection mechanism in embodiment 1.

[0031] Finally, it should be noted that the above implementation cases are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned implementation cases, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned implementation cases, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the implementation cases of the present invention.

Claims

1. A metal injection mechanism, characterized in that: The invention comprises a barrel (1) having an internal passage, a feeding unit (2), and a nozzle unit (3) connected to one end of the barrel (1), wherein the nozzle unit (3) is in communication with the internal passage of the barrel (1), and the feeding unit (2) is used to feed the slurry in the barrel (1) into the nozzle unit (3) and cause the slurry to flow out; the nozzle unit (3) is provided with a temperature control unit (4), and 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) solidifies to form a cold plug before injection, 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.

2. A metal injection mechanism according to claim 1, characterized in that: The nozzle unit (3) comprises at least a first nozzle pipe section (31) arranged at the front end of the barrel (1); one end of the first nozzle pipe section (31) is connected to the interior of the barrel (1) and the other end is provided with a first outlet (311); and the temperature control unit (4) is at least partially arranged on the first nozzle pipe section (31).

3. A metal injection mechanism according to claim 2, characterized in that: The nozzle unit (3) further comprises a second nozzle pipe section (32), the second nozzle pipe section (32) being in communication with the first outlet (311), the second nozzle pipe section (32) being provided with a second outlet (321), and the second nozzle pipe section (32) being provided with a gas inlet arranged towards the second outlet (321) and used for injecting a protective gas, and the temperature control unit (4) is at least partially arranged on the second nozzle pipe section (32).

4. A metal injection mechanism according to claim 3, characterized in that: The first nozzle pipe section (31) is connected to a side of the second nozzle pipe section (32), and a conveying path of the protective gas in the second nozzle pipe section (32) passes through the first outlet (311).

5. A metal injection mechanism according to claim 2, characterized in that: A connecting pipe section (34) is provided at one end of the first nozzle pipe section (31) close to the barrel (1); the connecting pipe section (34) is embedded in the barrel (1) and communicates with the interior of the barrel (1); the inner diameter of the connecting pipe section (34) is greater than the inner diameter of the first nozzle pipe section (31).

6. A metal injection mechanism according to claim 2, characterized in that: The first nozzle pipe section (31) is arranged to extend in a bent manner.

7. A metal injection mechanism according to claim 1, characterized in that: The barrel (1) is provided with a feed port (11), and the feed port (11) is communicated with an internal channel of the barrel (1).

8. A metal injection mechanism according to claim 7, characterized in that: The internal passage of the barrel (1) comprises a shooting section (12) and a feeding section (13) which are interconnected, the feeding unit (2) comprises a screw (21) arranged in the barrel (1) and a driving assembly (22) for controlling the screw (21) to perform rotational and linear motion, the feeding section (13) is formed in the screw (21), the shooting section (12) is connected to the nozzle unit (3), and the feed port (11) is connected to the feeding section (13).

9. A metal injection mechanism according to any one of claims 1 to 8, characterized in that: The temperature control unit (4) comprises a plurality of heating coils.

10. A metal injection molding machine, characterized in that: A metal injection mechanism comprising any one of claims 1 to 9.

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