A high precision metal injection molding mechanism and method

Abstract

The application relates to the technical field of metal injection molding, in particular to a high-precision metal injection molding mechanism and method. In actual production, the problem of deformation may occur during high-speed injection, which reduces the injection precision. After the connection driving mode of directly connecting an integrated piston, a piston rod and a feeding screw of a feeding unit, and connecting a storage driving assembly at the end side to provide movement power is adopted, the length of the piston and the feeding screw can be reduced under the premise of ensuring large storage capacity, the strength is improved, and then the stability of the mechanism is improved, so that the injection precision can be improved. Meanwhile, high-frequency response servo valves are arranged on the oil inlet side and the oil outlet side of an injection oil cylinder, double-response control is conducted, the valve opening degree is rapidly adjusted on the oil inlet side to control the injection speed, the injection speed is controlled by adjusting the oil inlet amount, and multi-section control of the injection speed is conducted.

Description

Technical Field

[0001] This invention relates to the field of metal injection molding technology, and in particular to a high-precision metal injection molding mechanism and method. Background Technology

[0002] Magnesium has a specific gravity approximately two-thirds that of aluminum and one-quarter that of iron, making it the lightest of the practical metals, while also possessing high strength and rigidity. Due to its low density, magnesium alloys offer significant advantages in lightweight design. These properties make magnesium alloys promising for various applications, such as lightweighting automotive parts.

[0003] Currently, magnesium alloy products are mainly produced using injection molding machines in conjunction with molds. An important method for molding magnesium alloys is semi-solid injection molding. Compared to other molding methods such as cold chamber die casting, semi-solid injection molding offers unparalleled advantages, such as energy saving (lower melting temperature of magnesium alloys: general magnesium alloy casting requires heating the alloy to 650-680°C, while injection molding only requires heating to 580-600°C), environmental friendliness (no need for protective gases: general magnesium alloy casting requires the use of harmful protective gases such as SF6 to prevent oxidation and combustion, while injection molding's molten magnesium alloy does not come into contact with air), and safety (although general magnesium alloy casting uses protective gases, there is still a risk of spontaneous combustion and explosion; injection molding's molten magnesium alloy is in a closed container, thus avoiding these risks).

[0004] The method for injection molding magnesium alloys involves feeding the magnesium alloy into a feed tube, heating it to a molten state, continuously feeding it through a rotating screw, and then injecting it at high speed to form the final product. Currently, there are many types of metal injection molding equipment using this process, but as the production precision requirements for magnesium alloy parts increase, existing injection molding equipment can no longer meet these needs.

[0005] Chinese patent application CN101524747A discloses a servo-controlled high-speed injection molding machine for semi-solid magnesium alloys, including a mold-locking mechanism, an injection mechanism, a hydraulic mechanism, an electrical mechanism, and a frame. The injection mechanism features an injection cylinder equipped with a hollow floating piston; the feeding system includes a feeding screw assembly capable of forming the microstructure of the semi-solid magnesium alloy; the hydraulic mechanism includes a cartridge valve and a high-response accumulator; the high-speed injection speed control system has a high-frequency response servo valve on the oil outlet side of the injection cylinder and two pressure sensors PS1 and PS2 on the oil outlet side to monitor the pressure on the oil outlet side of the injection cylinder in real time; the electrical mechanism includes a high-speed CPU module to control the high-speed injection speed in real-time closed-loop control. This patented device achieves closed-loop control of the injection speed during the injection process through the high-frequency response servo valve on the oil outlet side of the injection cylinder, enabling high-precision control of the injection speed and thus improving the accuracy of injection molding. However, this device still has the following drawbacks in terms of injection molding accuracy control:

[0006] (1) First, by using a high-frequency response servo valve, the injection volume accuracy can only be controlled by adjusting the valve opening. At the same time, there is a certain time difference in the response of the high-frequency response servo valve to adjust the valve opening, which makes it impossible to achieve real-time control of injection accuracy.

[0007] (2) Secondly, the precision control effect of the device depends on the response speed of the high-frequency response servo valve. Since the high-frequency response servo valve cannot play a deceleration and buffering role, it can only reduce the injection volume by reducing the valve opening. Long-term liquid impact can easily slow down the response speed of the high-frequency response servo valve, thus making the precision control effect of the device easily deteriorate.

[0008] (3) Third, relying on a single high-frequency servo valve to achieve precision control of the injection device has the defect of unstable effect. Summary of the Invention

[0009] In order to solve one or more of the above-mentioned technical problems and improve the accuracy of magnesium alloy injection molding, the present invention provides a high-precision metal injection molding mechanism and method.

[0010] The specific technical solution of this invention is as follows:

[0011] In a first aspect, the present invention provides a high-precision metal injection molding mechanism, comprising an injection unit, a hydraulic unit, and a feeding unit, wherein:

[0012] The injection unit includes an injection cylinder, an integrated piston and piston rod disposed within the injection cylinder;

[0013] The feeding unit includes a feeding screw and a storage drive assembly. The two ends of the integrated piston and piston rod are respectively connected to the feeding screw and the storage drive assembly. The integrated piston and piston rod are used to drive the feeding screw through the driving action of the storage drive assembly to deliver the injection liquid.

[0014] Both the inlet and outlet sides of the injection cylinder are equipped with high-frequency servo valves.

[0015] Researchers discovered in experiments that this invention, by employing an integrated piston and piston rod in the injection unit and directly connecting it to the feeding screw of the feeding unit, significantly improves the precision of metal injection molding. Further analysis reveals that in existing technologies, the piston within the injection cylinder is often connected to the feeding screw via a drive component or other connecting structure. Therefore, the total length of the piston and feeding screw is often quite long, resulting in insufficient strength. During high-speed injection in actual production, deformation can occur, leading to reduced injection precision. By adopting a connection and drive method where "an integrated piston and piston rod are directly connected to the feeding screw of the feeding unit, and the material storage drive assembly is connected to the end side to provide motion power," the length of the piston and feeding screw can be reduced while ensuring a large material storage capacity, thus increasing strength and improving the stability of the mechanism, thereby achieving improved injection precision.

[0016] High-frequency response servo valves are installed on both the inlet and outlet sides of the injection cylinder. The principle is that magnesium alloy is lighter than other metals. During actual injection, it has a greater acceleration when pushed by the same force. In the final stage of injection, it will have a larger injection speed compared with other metals. Therefore, the control of the injection accuracy of magnesium alloy is particularly important in the final stage. This invention sets high-frequency response servo valves on both the inlet and outlet sides of the injection cylinder to perform dual-response control. In addition to quickly adjusting the valve opening on the outlet side to control the injection speed, the oil inlet volume is controlled by adjusting the valve opening on the inlet side to regulate the piston's driving force, thus performing multi-stage control of the injection speed. Meanwhile, as described in the background section, the injection speed control effect of a high-frequency response servo valve depends on its response speed. However, the limited response speed of high-frequency response servo valves on the market makes it difficult to improve injection accuracy by simply replacing them with faster-responding products. In the metal injection molding mechanism provided by this invention, high-frequency response servo valves are installed on both the oil inlet and outlet sides of the injection cylinder for dual proportional valve ring control. Through multi-segment control of the injection speed, the problem of poor injection accuracy control caused by the slow response of a single high-frequency response servo valve on the outlet side can be avoided, and the problem that the response of a single high-frequency response servo valve cannot guarantee the stability of injection speed control can be overcome.

[0017] It is important to note that the oil inlet and outlet sides of the injection cylinder depend on the direction of linear motion of the integrated piston and piston rod. The piston section of the integrated piston and piston rod serves as the dividing line; the side in the direction of linear motion of the integrated piston and piston rod is the outlet side. That is, if one side is the outlet side during injection, it will become the inlet side during retraction.

[0018] As a preferred embodiment of the above-mentioned technical solution of the present invention, the oil outlet side of the injection cylinder is provided with a first oil outlet and a second oil outlet, the second oil outlet being close to the end of the injection cylinder, and the diameter of the second oil outlet being smaller than that of the first oil outlet.

[0019] One problem in existing technologies leading to poor precision in metal injection molding lies in speed control at high injection speeds. In the final stage of injection, the injection speed is high, and prolonged liquid impact can slow down the response speed of the high-frequency servo valve. This invention addresses this by setting two oil outlets, one large and one small, on the oil outlet side. The smaller outlet is located near the end of the injection cylinder. During injection, in the early and middle stages, oil is discharged through the larger outlet. In the final stage, the oil volume on the outlet side is lower and the speed is higher, so the second outlet provides speed buffering. Oil discharge from the outlet side directly affects the injection acceleration and speed control. Simultaneously, near the end of injection, the hydraulic structure needs to protect the mechanical structure from mechanical collisions. During injection, when the injection position reaches the edge of the larger outlet, the oil on the injection cylinder's outlet side returns to the oil tank through the smaller outlet, achieving a mechanical-hydraulic braking effect. This not only provides good speed buffering but also prevents impact damage to the mechanism.

[0020] It is important to note that the diameter of the second oil outlet is smaller than that of the first oil outlet. This can be understood as meaning that, at the same flow rate, the amount of oil discharged through the second oil outlet in the same amount of time is less than that through the first oil outlet. The limitation that the diameter of the second oil outlet is smaller than that of the first oil outlet does not imply that either the first or second oil outlet is circular.

[0021] As a preferred embodiment of the above-mentioned technical solution of the present invention, cylinder covers are provided at both ends of the injection cylinder to seal the inner cavity of the injection cylinder; the cylinder covers are provided with oil drain grooves.

[0022] The researchers of this invention discovered that improving the smoothness of oil return and discharge in the injection cylinder during the injection process can also improve the control effect of injection accuracy. This invention further improves the smoothness of oil discharge by providing an oil discharge groove on the injection cylinder used to seal the inner cavity of the injection cylinder, thereby buffering the flow of oil and improving the smoothness of oil discharge, particularly for improving the smoothness of oil discharge and return at the relative position of the second oil outlet within the inner cavity of the injection cylinder.

[0023] As a preferred embodiment of the above-mentioned technical solution of the present invention, a rotary sealing ring is provided on the piston section of the integrated piston and piston rod to ensure that the integrated piston and piston rod are in close contact with the inner wall of the injection cylinder.

[0024] The piston section of the integrated piston and piston rod is also provided with a pressure reducing ring and a wear-resistant ring. The pressure reducing ring is located on both sides of the rotary seal ring, and the wear-resistant ring is located on the side of the pressure reducing ring away from the rotary seal ring.

[0025] During injection, oil leakage in the injection cylinder, specifically the flow of oil from the outlet side to the inlet side, can lead to decreased injection precision control. The integrated piston and piston rod require both axial and rotational movement during operation. To meet the requirements of precise control and prevent oil leakage, the outer circumference of the piston section of the integrated piston and piston rod must have a high sealing requirement. This invention uses a rotary sealing ring on the piston section of the integrated piston and piston rod to ensure tight contact between the piston and piston rod and the inner wall of the injection cylinder for sealing. However, the sealing ring's application limit depends on the product of the oil pressure P and the moving speed V. The value of P*V is limited, and the seal is prone to failure during high-speed injection. This invention further solves the oil leakage problem by setting pressure-reducing rings on both sides of the rotary sealing ring, and then setting a wear-resistant ring on the side of the pressure-reducing ring furthest from the rotary sealing ring. This creates a seal between the inlet and outlet sides of the injection cylinder using a combination of a wear-resistant ring, pressure-reducing ring, rotary sealing ring, pressure-reducing ring, and wear-resistant ring on the piston section of the integrated piston and piston rod, thereby improving injection precision.

[0026] As a preferred embodiment of the above-mentioned technical solution of the present invention, the storage drive assembly includes a servo motor and a transmission shaft. The transmission shaft is connected to the integrated piston and piston rod via a spline. The servo motor drives the transmission shaft to rotate via a transmission belt, thereby causing the integrated piston and piston rod to move.

[0027] As a preferred embodiment of the above technical solution of the present invention, it further includes a hydraulic unit, wherein the hydraulic unit includes a first high-response accumulator and at least one nitrogen storage cylinder, the high-pressure nitrogen side of the high-response accumulator is connected to the nitrogen storage cylinder, and the oil outlet side of the high-response accumulator is connected to the oil inlet side of the injection cylinder.

[0028] A proportional throttle valve is installed on the oil outlet side of the high-response accumulator and the oil inlet side of the injection cylinder, and a second high-response accumulator is installed on the proportional throttle valve.

[0029] As a preferred embodiment of the above technical solution of the present invention, pressure sensors are respectively installed on the oil inlet side and the oil outlet side of the injection cylinder to detect the inlet and outlet pressures of the injection cylinder in real time.

[0030] By installing pressure sensors on both the inlet and outlet sides of the injection cylinder, the system pressure can be detected in real time. Real-time monitoring can improve the response speed and further enhance injection accuracy.

[0031] As a preferred embodiment of the above technical solution of the present invention, the high-precision metal injection molding mechanism further includes a transfer unit, wherein the transfer unit includes a bearing component, and the bearing component is connected to the barrel;

[0032] The adjustment and transfer unit also includes an injection seat, an adjustment and transfer cylinder, and an adjustment and transfer piston rod disposed inside the adjustment and transfer cylinder. The bearing component is connected to the adjustment and transfer piston rod. The injection seat pushes the adjustment and transfer piston rod to move inside the adjustment and transfer cylinder, so that the material cylinder moves relative to the fixed template.

[0033] As a preferred embodiment of the above-mentioned technical solution of the present invention, the high-precision metal injection molding mechanism further includes a rotating unit, the rotating unit including a rotating cylinder and a rotating piston rod disposed inside the rotating cylinder; the rotating unit also includes a middle base plate and a lower base plate connected to each other, the middle base plate and the lower base plate being respectively connected to the rotating cylinder, and a rotating positioning pin being provided between the middle base plate and the lower base plate; when the rotating piston rod moves inside the rotating cylinder, the middle base plate rotates around the lower base plate with the rotating positioning pin as the center.

[0034] Secondly, the present invention also provides a method for high-precision metal injection molding, comprising the following steps:

[0035] S1: The injection unit adopts an integrated piston and piston rod connected to the feeding screw, which shortens the length of the injection unit and reduces the deformation of the metal injection molding mechanism;

[0036] S2: Increase the sealing performance between the integrated piston and piston rod and the injection cylinder;

[0037] S3: The injection unit is equipped with a deceleration structure to slow down and buffer the injection speed at the end of the injection process.

[0038] S4: Both the inlet and outlet sides of the injection cylinder are equipped with high-frequency servo valves, which provide high dynamic response to user commands.

[0039] Thirdly, based on the above-mentioned high-precision metal injection molding mechanism or the above-mentioned high-precision metal injection molding method, the present invention also provides a high-precision metal injection molding machine.

[0040] This high-precision metal injection molding machine includes the aforementioned high-precision metal injection molding mechanism. Using this molding machine for magnesium alloy metal injection molding offers the advantage of high precision.

[0041] Compared with the prior art, the present invention has the following technical effects:

[0042] (1) The present invention provides a high-precision metal injection molding mechanism, the advantages of which are:

[0043] ① In existing technologies, the piston in the injection cylinder is often connected to the feeding screw via a drive component or other connecting structures. Therefore, the total length of the piston and feeding screw is often quite long, resulting in insufficient strength. In actual production, high-speed injection can lead to deformation and reduced injection accuracy. By adopting a connection and drive method that directly connects the integrated piston and piston rod to the feeding screw of the feeding unit, and connects the material storage drive component to the end side to provide motion power, the length of the piston and feeding screw can be reduced while ensuring a large material storage capacity, thereby increasing strength and improving the stability of the mechanism. This can improve injection accuracy.

[0044] ② Furthermore, this invention provides high-frequency response servo valves on both the inlet and outlet sides of the injection cylinder. Magnesium alloys are lighter than other metals, resulting in greater acceleration when injected with the same force. In the final stage of injection, they exhibit a higher injection speed compared to other metals. Therefore, controlling the injection accuracy of magnesium alloys is particularly important in the final stage. This invention provides high-frequency response servo valves on both the inlet and outlet sides of the injection cylinder for dual response. Besides rapidly adjusting the valve opening on the outlet side to control the injection speed, it also controls the oil intake by rapidly adjusting the valve opening on the inlet side to regulate the piston's driving force, thus achieving multi-stage control of the injection speed.

[0045] ③ This invention further improves the smoothness of oil discharge by providing an oil drain groove on the injection cylinder used to seal the inner cavity of the injection cylinder, thereby buffering the flow of oil and improving the smoothness of oil discharge, especially for improving the smoothness of oil discharge and return at the relative position of the second oil outlet within the inner cavity of the injection cylinder. This invention further improves the control effect of injection precision by improving the smoothness of oil return and discharge in the injection cylinder.

[0046] ④ The present invention further provides pressure relief rings on both sides of the rotary sealing ring, and then provides a wear-resistant ring on the side of the pressure relief ring away from the rotary sealing ring, so as to seal the oil inlet and outlet sides of the injection cylinder by setting "wear-resistant ring, pressure relief ring, rotary sealing ring, pressure relief ring, and wear-resistant ring" on the piston section of the integrated piston and piston rod, thereby solving the problem of oil leakage and improving injection accuracy.

[0047] (2) The present invention also provides a high-precision metal injection molding method. Using this method to perform magnesium alloy metal injection molding has the characteristic of injection precision control.

[0048] (3) The present invention also provides a high-precision metal injection molding machine. Using this injection molding machine to perform magnesium alloy metal injection molding has the feature of injection precision control. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the structure of a high-precision metal injection molding mechanism according to the present invention;

[0051] Figure 2 This is a cross-sectional view of a high-precision metal injection molding mechanism according to the present invention.

[0052] Figure 3 for Figure 2 A cross-sectional schematic diagram of the piston section structure, consisting of a single piston and piston rod.

[0053] Figure 4 for Figure 2 A cross-sectional view of the piston section on the oil outlet side of the injection cylinder.

[0054] Figure 5 for Figure 1 Cross-sectional view of the injection detection unit;

[0055] Figure 6 for Figure 1 Another structural schematic diagram of the injection detection unit;

[0056] Figure 7 for Figure 1 A schematic diagram of a structural unit for repositioning and shifting;

[0057] Figure 8 for Figure 1 A schematic diagram of a central shifting unit and a rotating unit;

[0058] Figure 9 for Figure 1 A schematic diagram of a lifting unit;

[0059] Figure 10 for Figure 1 The present invention relates to a hydraulic control principle diagram of a high-precision metal injection molding mechanism.

[0060] The attached figures are labeled as follows: 100, injection unit; 101, integrated piston and piston rod; 102, injection cylinder; 1021, first oil outlet; 1022, second oil outlet; 103, cylinder head; 1031, oil drain groove; 104, wear ring; 105, pressure reducing ring; 106, rotary seal ring; 200, feeding unit; 201, feeding screw; 202, material cylinder; 203, material storage drive assembly; 2031, servo motor; 2032, small pulley; 2033, synchronous belt; 2034, large pulley; 2035, drive shaft; 300, injection test sheet. Yuan, 301, Stroke seat, 302, Bearing, 303, Stroke rod, 304, Magnetic scale, 305, Reading head, 400, Adjustment unit, 401, Fixed template, 402, Adjustment cylinder barrel, 403, Adjustment piston rod, 404, Middle base plate, 405, Guide rail, 406, Slider, 407, Limit block, 408, Fixing block, 409, Injection seat, 410, Bearing assembly, 500, Rotation unit, 501, Lower base plate, 502, Rotation cylinder barrel, 503, Rotation piston rod, 504, Rotation positioning pin, 505, Copper pad, 600, Lifting unit, 601, Guide column, 602, Base hole, 603, Lifting cylinder, A, Oil inlet side during injection, B, Oil outlet side during injection. Detailed Implementation

[0061] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0062] In the following description, several embodiments of this application are provided. Different embodiments can be substituted or combined. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0063] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0064] Example 1:

[0065] This embodiment provides a high-precision metal injection molding mechanism, such as Figures 1-10As shown.

[0066] like Figure 1 , Figure 2 , Figure 3 As shown, a high-precision metal injection molding mechanism includes an injection unit 100, a hydraulic unit, a feeding unit 200, and an electrical unit. The injection unit 100 includes an injection cylinder 102 and an integrated piston and piston rod 101 housed within the injection cylinder 102. The feeding unit 200 includes a feeding screw 201 and a material storage drive assembly 203. The two ends of the integrated piston and piston rod 101 are respectively connected to the feeding screw 201 and the material storage drive assembly 203, and are used to drive the integrated piston and piston rod 101 to move the feeding screw 201 through the driving action of the material storage drive assembly 203, thereby delivering the injection liquid. High-frequency servo valves are installed on both the oil inlet and outlet sides of the injection cylinder 102.

[0067] The oil inlet and outlet sides of the injection cylinder 102 depend on the direction of linear movement of the integrated piston and piston rod 101. The piston section of the integrated piston and piston rod 101 serves as the boundary; the side in the direction of linear movement of the integrated piston and piston rod 101 is the outlet side. That is, during injection, if one side is the outlet side, then during retraction, that side will become the inlet side. For example... Figure 2 As shown, during injection, area A is the oil inlet side and area B is the oil outlet side.

[0068] By adopting a connection and drive method that "directly connects the integrated piston and piston rod 101 to the feeding screw 201 of the feeding unit 200, and connects the material storage drive assembly 203 to the end side to provide motion power", the length of the piston and feeding screw 201 can be reduced while ensuring a large material storage capacity, thereby increasing the strength and stability of the mechanism. This can improve the injection accuracy and has a significant effect on improving the precision of metal injection molding.

[0069] Magnesium alloys are lighter than other metals, resulting in greater acceleration when injected with the same force. This leads to a higher injection speed in the final stages compared to other metals. Therefore, controlling the injection accuracy of magnesium alloys is crucial in the final stages. This invention incorporates high-frequency servo valves on both the inlet and outlet sides of the injection cylinder 102 for dual-response operation. In addition to rapidly adjusting the valve opening on the outlet side to control the injection speed, the valve opening on the inlet side also rapidly adjusts the oil inflow to regulate the piston's injection speed, enabling multi-stage control of the injection speed.

[0070] As a preferred embodiment, pressure sensors are respectively installed on the oil inlet and oil outlet sides of the injection cylinder 102 to detect the system pressure in real time. By installing pressure sensors on the oil inlet and oil outlet sides of the injection cylinder 102 to detect the system pressure in real time, the response speed can be improved, thereby further improving the injection accuracy.

[0071] like Figure 4 As shown, in a preferred embodiment, the oil outlet side of the injection cylinder 102 is provided with a first oil outlet 1021 and a second oil outlet 1022. The second oil outlet 1022 is close to the end of the injection cylinder 102, and the diameter of the second oil outlet 1022 is smaller than that of the first oil outlet 1021.

[0072] By setting two oil outlets, one large and one small, on the oil outlet side, with the smaller outlet located near the end of the injection cylinder 102, oil is discharged through the larger outlet 1021 during the initial and intermediate stages of injection. In the final stage, the oil volume on the outlet side is smaller and the speed is higher, so the second outlet 1022 provides speed buffering. The oil discharge on the outlet side directly affects the injection acceleration and speed control. Simultaneously, near the end of injection, the hydraulic structure needs to protect the mechanical structure from mechanical collisions. During injection, when the injection position reaches the edge of the larger outlet, the oil on the outlet side of the injection cylinder 102 returns to the oil tank through the smaller outlet, the second outlet 1022, achieving a mechanical-hydraulic brake. This not only provides good speed buffering but also prevents impact damage to the mechanism. The oil flow rate is controlled by a one-way throttle valve.

[0073] The second oil outlet 1022 has a smaller diameter than the first oil outlet 1021. This can be understood as meaning that, at the same flow rate, the amount of oil discharged through the second oil outlet 1022 in the same amount of time is less than that discharged through the first oil outlet 1021. The limitation that the diameter of the second oil outlet 1022 is smaller than that of the first oil outlet 1021 is not a limitation that the first oil outlet 1021 and the second oil outlet 1022 are circular.

[0074] like Figure 4 As shown, in a preferred embodiment, the injection cylinder 102 is provided with cylinder covers 103 at both ends to seal the inner cavity of the injection cylinder 102; the cylinder covers 103 are provided with oil drain grooves. This embodiment further provides oil drain grooves 1031 on the injection cylinder 102 used to seal the inner cavity of the injection cylinder 102, which buffers the flow of oil and improves the smoothness of oil draining. In particular, it improves the smoothness of oil discharge and return at the relative position of the second oil outlet 1022 within the inner cavity of the injection cylinder 102, thereby enhancing the control effect of injection accuracy by improving the smoothness of oil return and discharge in the injection cylinder 102 during the injection process.

[0075] like Figure 3As shown, in a preferred embodiment, the piston section of the integrated piston and piston rod 101 is provided with a rotary sealing ring 106 to ensure that the integrated piston and piston rod 101 are in close contact with the inner wall of the injection cylinder 102; the piston section of the integrated piston and piston rod 101 is also provided with a pressure reducing ring 105 and a wear-resistant ring 104, the pressure reducing ring 105 being provided on both sides of the rotary sealing ring 106, and the wear-resistant ring 104 being provided on the side of the pressure reducing ring 105 away from the rotary sealing ring 106.

[0076] The integrated piston and piston rod 101 require both axial and rotational movement during operation. To meet precise control requirements and prevent oil leakage, the outer circumference of the piston section of the integrated piston and piston rod 101 requires a high degree of sealing. This invention utilizes a rotary sealing ring 106 on the piston section of the integrated piston and piston rod 101 to ensure tight contact between the integrated piston and piston rod 101 and the inner wall of the injection cylinder 102, thus achieving a seal. However, the sealing ring's application limit depends on the product of the oil pressure P and the moving speed V. The value of P*V is finite, and the seal is prone to failure during high-speed injection. The present invention further provides pressure relief rings 105 on both sides of the rotary sealing ring 106, and then provides a wear-resistant ring 104 on the side of the pressure relief ring 105 away from the rotary sealing ring 106. By providing "wear-resistant ring 104, pressure relief ring 105, rotary sealing ring 106, pressure relief ring 105, and wear-resistant ring 104" in the piston section of the integrated piston and piston rod 101, the oil inlet and outlet sides of the injection cylinder 102 are sealed, thereby solving the problem of oil leakage and improving injection accuracy.

[0077] like Figure 5 and Figure 6 As shown, the high-precision metal injection molding mechanism also includes an injection detection unit 300. The injection detection unit 300 is connected to the outside of the integrated piston and piston rod 101. The injection detection unit 300 includes a stroke seat 301, a bearing 302, a stroke rod 303, a magnetic scale 304, and a reading head 305.

[0078] The stroke seat 301 and the integrated piston and piston rod 101 move axially simultaneously. While the integrated piston and piston rod 101 rotate, the stroke seat 301 does not rotate due to the presence of the bearing 302. The stroke rod 303 is fastened to the stroke seat 301 and moves axially simultaneously. A magnetic scale 304 is mounted on the stroke rod 303. The reading head 305 detects the positional movement of the magnetic scale 304 and calculates the movement speed based on the relationship between positional movement and movement time. Thus, when the integrated piston and piston rod 101 drive the screw forward and backward, the reading head 305 detects the positional movement of the magnetic scale 304 to calculate the position and speed of the screw movement, thereby calculating the injection volume.

[0079] like Figure 2As shown, in a preferred embodiment, the material storage drive assembly 203 includes a servo motor 2031 and a drive shaft 2035. The drive shaft 2035 is connected to the integrated piston and piston rod 101 via a spline. The servo motor 2031 drives the drive shaft 2035 to rotate via a transmission belt, thereby causing the integrated piston and piston rod 101 to move. Based on the connection and drive method of "the integrated piston and piston rod 101 is directly connected to the feeding screw 201 of the feeding unit 200, and the material storage drive assembly 203 is connected to the end side to provide motion power", this embodiment sets the drive shaft 2035 to be connected to the integrated piston and piston rod 101 via a spline to more flexibly control the movement of the feeding screw 201. With the spline connection, it is possible to achieve the effect of moving a section of the rod while the end rod remains stationary when necessary.

[0080] like Figure 10 As shown in the preferred embodiment, the high-precision metal injection molding mechanism further includes a hydraulic unit. The hydraulic unit includes a first high-response accumulator and a nitrogen storage cylinder of suitable volume. The high-pressure nitrogen side of the high-response accumulator is connected to the nitrogen storage cylinder, and the oil outlet side of the high-response accumulator is connected to the oil inlet side of the injection cylinder 102. A proportional throttle valve is installed on the oil outlet side of the high-response accumulator and the oil inlet side of the injection cylinder 102. A second high-response accumulator is installed on the proportional throttle valve. By installing the second high-response accumulator, a small accumulator is installed on the proportional valve to provide pilot oil to the injection cylinder 102, maintaining the proportional valve's high dynamic response.

[0081] like Figure 7 , Figure 8 As shown in the preferred embodiment, the high-precision metal injection molding mechanism further includes a transfer unit 400. The transfer unit 400 includes an injection seat 409, a support assembly 410, a transfer cylinder 402, and a transfer piston rod 403 disposed within the transfer cylinder 402. The fixed template 401 is connected to the transfer piston rod 403, and the injection seat 409 is connected to the barrel 202. When the injection seat 409 pushes the transfer cylinder 402 to move, the barrel 202 and the fixed template 401 move relative to each other. The transfer unit 400 facilitates adjustment of the distance between the injection seat 409 and the fixed template 401, making mold disassembly easier.

[0082] like Figure 7 , Figure 8As shown in the preferred embodiment, the high-precision metal injection molding mechanism further includes a rotating unit 500. The rotating unit 500 includes a rotating cylinder 502 and a rotating piston rod 503 disposed within the rotating cylinder 502. The rotating unit 500 also includes a middle base plate 404 and a lower base plate 501 connected to each other. The middle base plate 404 and the lower base plate 501 are respectively connected to the rotating cylinder 502. A rotating positioning pin 504 is provided between the middle base plate 404 and the lower base plate 501. When the rotating piston rod 503 moves within the rotating cylinder 502, the middle base plate 404 rotates around the lower base plate 501 with the rotating positioning pin 504 as its center. The rotating unit 500 facilitates the periodic replacement of the nozzle, screw, and barrel 202. In this embodiment, limit blocks 407 are provided at both ends of the middle base plate 404 to prevent the slider 406, the bearing assembly 410, and the parts on it from sliding off the guide rail during assembly and maintenance.

[0083] like Figure 8 , Figure 9 As shown in the preferred embodiment, the high-precision metal injection molding mechanism further includes a lifting unit 600, which includes a lower base plate 501 and a guide post 601 disposed below the lower base plate 501. The guide post 601 provides guidance between itself and the base hole 602. A lifting cylinder 603 can push the lower base plate 501 up and down, thereby pushing the entire injection seat 409 up and down. This adapts to different work positions.

[0084] Compared with the prior art, this embodiment has the following technical effects:

[0085] ① In existing technologies, the piston in the injection cylinder is often connected to the feeding screw via a drive component or other connecting structures. Therefore, the total length of the piston and feeding screw is often quite long, resulting in insufficient strength. In actual production, high-speed injection can lead to deformation and reduced injection accuracy. By adopting a connection and drive method that directly connects the integrated piston and piston rod to the feeding screw of the feeding unit, and connects the material storage drive component to the end side to provide motion power, the length of the piston and feeding screw can be reduced while ensuring a large material storage capacity, thereby increasing strength and improving the stability of the mechanism. This can improve injection accuracy.

[0086] ② Furthermore, this invention provides high-frequency response servo valves on both the inlet and outlet sides of the injection cylinder. Magnesium alloys are lighter than other metals, resulting in greater acceleration when injected with the same force. In the final stage of injection, they exhibit a higher injection speed compared to other metals. Therefore, controlling the injection accuracy of magnesium alloys is particularly important in the final stage. This invention provides high-frequency response servo valves on both the inlet and outlet sides of the injection cylinder for dual-response control. In addition to rapidly adjusting the valve opening on the outlet side to control the injection speed, the invention also controls the oil inflow by rapidly adjusting the valve opening on the inlet side, thereby regulating the piston's injection speed and achieving multi-stage control of the injection speed.

[0087] ③ This invention further improves the smoothness of oil discharge by providing an oil drain groove on the injection cylinder used to seal the inner cavity of the injection cylinder, thereby buffering the flow of oil and improving the smoothness of oil discharge, especially for improving the smoothness of oil discharge and return at the relative position of the second oil outlet within the inner cavity of the injection cylinder. This invention further improves the control effect of injection precision by improving the smoothness of oil return and discharge in the injection cylinder.

[0088] ④ The present invention further provides pressure relief rings on both sides of the rotary sealing ring, and then provides a wear-resistant ring on the side of the pressure relief ring away from the rotary sealing ring, so as to seal the oil inlet and outlet sides of the injection cylinder by setting "wear-resistant ring, pressure relief ring, rotary sealing ring, pressure relief ring, and wear-resistant ring" on the piston section of the integrated piston and piston rod, thereby solving the problem of oil leakage and improving injection accuracy.

[0089] Based on the above technical effects, the high-precision metal injection molding mechanism provided in this embodiment can be steplessly adjusted from 0.05 to 5 m / s, and has high speed and high acceleration, which can realize high-precision injection at high speed and improve product performance.

[0090] Example 2:

[0091] Based on the high-precision metal injection molding mechanism provided in Embodiment 1, this embodiment provides a high-precision metal injection molding method, including the following steps:

[0092] S1: The injection unit adopts an integrated piston and piston rod connected to the feeding screw, which shortens the length of the injection unit and reduces the deformation of the metal injection molding mechanism;

[0093] S2: Increase the sealing performance between the integrated piston and piston rod and the injection cylinder;

[0094] S3: The injection unit is equipped with a deceleration structure to slow down and buffer the injection speed at the end of the injection process.

[0095] S4: Both the inlet and outlet sides of the injection cylinder are equipped with high-frequency servo valves, which provide high dynamic response to user commands.

[0096] The high-precision metal injection molding method provided in this embodiment for magnesium alloy metal injection molding has the advantage of effective injection precision control. The specific principle is described in Embodiment 1 and will not be elaborated further here.

[0097] Example 3:

[0098] Based on the high-precision metal injection molding mechanism provided in Embodiment 1 or the high-precision metal injection molding method provided in Embodiment 2, this embodiment provides a high-precision metal injection molding machine. This high-precision metal injection molding machine includes the aforementioned high-precision metal injection molding mechanism.

[0099] The high-precision metal injection molding machine provided in this embodiment is used for magnesium alloy metal injection molding, which features effective control over injection precision. The specific principle is described in Embodiment 1 or Embodiment 2, and will not be elaborated further here.

[0100] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0101] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0102] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A high-precision metal injection molding mechanism, comprising an injection unit, a hydraulic unit, and a feeding unit, characterized in that: the injection unit (100) comprises an injection cylinder (102) and an integrated piston and piston rod (101) arranged in the injection cylinder (102); the feeding unit (200) comprises a feeding screw (201) and a storage driving assembly (203), and the two ends of the integrated piston and piston rod (101) are connected with the feeding screw (201) and the storage driving assembly (203) respectively, so that the integrated piston and piston rod (101) drives the feeding screw (201) to move to realize the delivery of injection liquid under the driving action of the storage driving assembly (203); the oil inlet side and the oil outlet side of the injection cylinder (102) are provided with high-frequency response servo valves; the two ends of the injection cylinder (102) are provided with cylinder covers (103) for sealing the inner cavity of the injection cylinder (102), and the cylinder covers (103) are provided with oil discharge grooves (1031); the piston section of the integrated piston and piston rod (101) is provided with a rotary sealing ring (106) for tightly contacting the inner wall of the injection cylinder (102); the piston section of the integrated piston and piston rod (101) is further provided with a pressure relief ring (105) and a wear-resistant ring (104), the pressure relief ring (105) is arranged on the two sides of the rotary sealing ring (106), and the wear-resistant ring (104) is arranged on the side of the pressure relief ring (105) away from the rotary sealing ring (106); the oil outlet side of the injection cylinder (102) is provided with a first oil outlet (1021) and a second oil outlet (1022), the second oil outlet (1022) is close to the end of the injection cylinder (102), and the diameter of the second oil outlet (1022) is smaller than that of the first oil outlet (1021). The storage driving assembly (203) comprises a servo motor (2031) and a transmission shaft (2035), the transmission shaft (2035) is connected with the integrated piston and piston rod (101) through a spline, and the servo motor (2031) drives the transmission shaft (2035) to rotate through a transmission belt, so that the integrated piston and piston rod (101) moves. The hydraulic unit comprises a first high-response accumulator and at least one nitrogen gas cylinder, the high-pressure nitrogen side of the first high-response accumulator is connected with the nitrogen gas cylinder, and the oil outlet side of the first high-response accumulator is connected with the oil inlet side of the injection cylinder (102); the oil outlet side of the first high-response accumulator and the oil inlet side of the injection cylinder (102) are provided with a proportional throttle valve, and the proportional throttle valve is provided with a second high-response accumulator. The hydraulic unit further comprises a moving unit (400), the moving unit (400) comprises an injection seat (409), a moving cylinder barrel (402), and a moving piston rod (403) arranged in the moving cylinder barrel (402), the moving piston rod (403) is connected with a fixed mold plate, the injection seat (409) is connected with a barrel, and the injection seat (409) is used to drive the moving cylinder barrel (402) to move, so that the barrel and the fixed mold plate move relatively. ​ ​ ​ ​ 2. A high precision metal injection molding mechanism as claimed in claim 1, characterized in that: ​ 3. A high precision metal injection molding mechanism as defined in claim 1, wherein: ​ ​ 4. A high precision metal injection molding mechanism as defined in claim 1, wherein: ​ 5. A high precision metal injection molding mechanism as defined in claim 1, wherein: The application also discloses a rotating unit (500), which comprises a rotating oil cylinder (502) and a rotating piston rod (503) arranged in the rotating oil cylinder (502); the rotating unit (500) further comprises a middle bottom plate (404) and a lower bottom plate (501) connected with each other, the middle bottom plate (404) and the lower bottom plate (501) are connected with the rotating oil cylinder (502) respectively, and a rotating positioning pin (504) is arranged between the middle bottom plate (404) and the lower bottom plate (501); when the rotating piston rod (503) moves in the rotating oil cylinder (502), the middle bottom plate (404) rotates around the lower bottom plate (501) with the rotating positioning pin (504) as the center.

6. A method of high precision metal injection molding based on the high precision metal injection molding mechanism according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1: the injection unit is connected with the feeding screw through an integrated piston and piston rod, so that the length of the injection unit is shortened and the deformation of the metal injection molding mechanism is reduced; S2: the sealing performance of the integrated piston and piston rod and the injection cylinder is improved; S3: the injection unit is provided with a speed reduction structure, so that the injection speed is reduced and buffered at the end stage of injection; S4: high-frequency response servo valves are arranged on the oil inlet side and the oil outlet side of the injection cylinder, and the high dynamic response can respond to the instruction of a user.

7. A high precision metal injection molding machine characterized by: The high-precision metal injection molding mechanism comprises any one of claims 1-5.

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