A die-casting mold for a metal packaging can

Abstract

The application relates to the technical field of die-casting forming of metal packaging cans, in particular to a die-casting forming die for metal packaging cans, which comprises an upper die assembly, a lower die assembly and a side core-pulling mechanism, the upper die is provided with a flow channel with a flow divider and a multi-point inner gate, the lower die is provided with a spiral cooling water channel, a micron-level exhaust groove and a porous ceramic exhaust insert are arranged on a parting surface, the side core-pulling mechanism is linked with an inclined guide pin and a return spring, the surface of a cavity is covered with a DLC coating, and a core is provided with a micro-texture and coated with a TiN coating. The application can realize smooth filling of metal liquid, uniform cooling, efficient exhaust and smooth demolding, and effectively solves the problems of uneven filling, pores, shrinkage, demolding difficulty and surface burrs.

Description

Technical Field

[0001] This utility model relates to the field of metal packaging container manufacturing technology, and in particular to a die-casting mold for metal packaging cans. Background Technology

[0002] With the development of metal packaging container manufacturing technology, metal packaging cans are widely used in the food, beverage, and chemical industries due to their high strength, good sealing performance, and recyclability. Die casting is an important manufacturing process in the production of metal packaging cans. However, existing die casting molds still present many problems when used for metal packaging can molding. For example, traditional die casting molds are mostly designed for structural components or mechanical parts, failing to fully consider the characteristics of metal packaging cans, such as thin walls, deep cavities, and high surface quality requirements. This leads to problems such as uneven filling, porosity, shrinkage, difficulty in demolding, and surface burrs in actual production, affecting product yield and production efficiency.

[0003] A search revealed a die-casting machine and its production method for producing metal can packaging boxes, with publication number CN116786787A, filed on June 29, 2023. While this solution mentions die-casting of "metal can packaging boxes" and includes a demolding mechanism and pneumatic-assisted ejection structure, its technical focus is on improving a general demolding method. It fails to optimize the mold flow channels, venting, and temperature control specifically for the deep-cavity, thin-walled structure of metal packaging cans. Furthermore, it lacks a systematic design for key process parameters such as the stability of molten metal filling and the uniformity of mold cooling, making it difficult to meet the continuous production requirements of high-quality metal packaging cans.

[0004] A search revealed an automatic tank forming machine with publication number CN219924366U, authorized on October 31, 2023. This utility model focuses on subsequent machining processes such as bottom sealing, necking, and edge rolling of the tank, employing a multi-station transfer method for automation. However, its core is not die casting, but rather secondary processing of the already formed tank. The die casting part is only briefly mentioned as a pre-processing step, without addressing structural innovations in the die casting mold itself. In particular, it lacks specific design for the flow and solidification behavior of molten metal in a deep cavity mold, failing to solve internal defects caused by uneven cooling or poor venting during the die casting process.

[0005] The aforementioned problems indicate that while existing technologies include die-casting or molding equipment for "cans" or "metal cans," they either fail to focus on the die-casting mold's structure or lack specific optimization for the unique geometric features and process requirements of metal packaging cans. Therefore, there is an urgent need for a dedicated die-casting mold for metal packaging cans that can effectively improve filling flow, enhance venting, balance cooling rates, and achieve smooth demolding, thereby improving product quality and production efficiency. This utility model, "A Die-casting Mold for Metal Packaging Cans," is proposed based on this need. Utility Model Content

[0006] The purpose of this utility model is to provide a die-casting mold for metal packaging cans, so as to solve the problems mentioned in the background art that existing die-casting molds, when forming metal packaging cans, do not have structural optimization for thin walls, deep cavities and high surface quality requirements, resulting in uneven filling, air holes, shrinkage, difficulty in demolding and surface burrs, which in turn affect product yield and production efficiency.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a die-casting mold for metal packaging cans, comprising an upper mold assembly, a lower mold assembly, and a side core-pulling mechanism disposed between the two. The bottom of the upper mold assembly is provided with a cavity groove that matches the top contour of the metal packaging can, and the top of the lower mold assembly is provided with a core boss that matches the bottom contour of the metal packaging can. The cavity groove and the core boss together enclose the mold in the mold-closed state to form a closed mold cavity for forming the overall shape of the metal packaging can. The upper mold assembly is embedded with a ring-shaped distribution of flow divider cone channels. The inlet end of the flow divider cone channels is connected to the sprue sleeve of an external die-casting machine, and the outlet end is connected to the closed mold cavity through multiple radially arranged ingates. Each ingate is evenly distributed along the circumference of the metal packaging can, and the cross-sectional height of the ingate is less than one-third of the wall thickness of the metal packaging can. The outlet direction of the ingate is consistent with the flow direction of the molten metal in the mold cavity, so as to guide the molten metal to fill smoothly along the axial direction of the can.

[0008] Preferably, the lower mold assembly is provided with a cooling water channel system, which includes a main water inlet channel, a main water return channel, and several spiral cooling branches arranged around the outer periphery of the core boss. One end of each spiral cooling branch is connected to the main water inlet channel, and the other end is connected to the main water return channel. The diameter of the spiral cooling branch is 8mm to 12mm, and the axial spacing between adjacent spiral cooling branches is 15mm to 20mm. The centerline of the spiral cooling branch maintains a constant distance of 10mm to 15mm from the outer surface of the core boss, so that the cooling medium forms a uniform temperature gradient field around the core boss.

[0009] Preferably, the upper mold assembly and the lower mold assembly are respectively provided with mutually aligned venting grooves on their parting surfaces. The venting grooves are located at the corresponding positions of the highest filling area of ​​the metal packaging can. The depth of the venting grooves is 0.08mm to 0.12mm, and the width is 3mm to 5mm. The end of the venting groove is connected to a gas collecting chamber. The gas collecting chamber is connected to the atmosphere through a venting insert. The venting insert is made of porous ceramic material with a porosity of 30% to 40% and an average pore diameter of 50μm to 80μm. The venting insert is embedded in the side wall of the upper mold assembly or the lower mold assembly, and its outer end face is flush with the outer surface of the mold.

[0010] Preferably, the side core-pulling mechanism includes a slider seat, an inclined guide post, and a return spring. The slider seat is slidably installed in the side groove of the lower mold assembly. The inner end face of the slider seat is provided with a forming insert that matches the concave structure of the side wall of the metal packaging can. One end of the inclined guide post is fixed to the side wall of the upper mold assembly, and the other end passes through the inclined hole on the slider seat. The axis of the inclined guide post forms an angle of 15° to 20° with the mold opening and closing direction. The return spring is sleeved on the outside of the inclined guide post, with one end abutting against the slider seat and the other end abutting against the limiting step of the lower mold assembly. During the mold closing process, the upper mold assembly moves downward, driving the inclined guide post to push the slider seat towards the center of the mold cavity, so that the forming insert is embedded in the side wall of the mold cavity. During the mold opening process, the upper mold assembly moves upward, and the return spring pushes the slider seat to slide outward along the groove, so that the forming insert is disengaged from the side wall of the metal packaging can.

[0011] Preferably, the inner surface of the cavity groove of the upper mold assembly is coated with a diamond-like carbon (DLC) coating with a thickness of 1.5 μm to 2.5 μm and a surface roughness Ra value of no more than 0.05 μm; the outer surface of the core boss of the lower mold assembly is provided with a micro-textured array, which consists of circular pits with a diameter of 0.1 mm and a depth of 0.05 mm, arranged in a square grid, with a center distance of 0.5 mm between adjacent pits, and the surface of the micro-textured array is also covered with a titanium nitride (TiN) hard coating with a thickness of 1.2 μm to 2.0 μm.

[0012] Preferably, the central axis of the flow divider conical channel coincides with the vertical center line of the upper mold assembly, the cone angle of the flow divider conical channel is 30° to 45°, its inner wall is mirror polished, and the surface roughness Ra value is not greater than 0.02μm; the inlet end of each ingate is tangentially connected to the cone surface of the flow divider conical channel, and the outlet end extends to the bottom area of ​​the closed mold cavity and is inclined upward at 5° to 8° along the height direction of the metal packaging can to avoid the molten metal directly impacting the top of the core boss and causing splashing or air entrapment.

[0013] Preferably, the volume of the gas collection chamber is 1.5 cm³ to 2.5 cm³, and its inner wall is provided with guide ribs. The guide ribs are radially distributed along the exhaust direction. The height of the guide ribs is 0.3 mm to 0.5 mm, the width is 1 mm to 1.5 mm, the included angle between adjacent guide ribs is 30°, and the end of the guide ribs is smoothly connected to the air inlet end face of the exhaust insert to guide the gas into the internal pore channel of the exhaust insert in an orderly manner.

[0014] Preferably, a lubrication reservoir is provided between the slider seat and the slide groove of the lower mold assembly. The lubrication reservoir is located on the bottom surface of the slide groove, is distributed in a strip shape, and its length is consistent with the stroke of the slider seat. The lubrication reservoir is filled with high-temperature lithium-based grease. The bottom surface of the slider seat is provided with oil seepage holes corresponding to the lubrication reservoir. The diameter of the oil seepage holes is 0.8mm to 1.2mm, and they are arranged at equal intervals along the sliding direction of the slider seat with a spacing of 20mm to 25mm, so as to continuously release the lubricating medium during the reciprocating motion of the slider seat, reduce frictional resistance, and prevent high-temperature adhesion.

[0015] The beneficial effects of this utility model are as follows: by combining the diverting cone flow channel with multi-point ingates, and with precise control of the ingate size and direction, the molten metal is smoothly filled along the axial direction of the tank, reducing turbulence and air entrapment; by setting spiral cooling branches around the core boss in the lower mold assembly, a uniform cooling field is formed, suppressing shrinkage defects; by setting micron-level venting grooves and porous ceramic venting inserts at the high point of the parting surface, efficient venting without overflow is achieved; by cooperating with the inclined guide post-slider structure and return spring of the side core pulling mechanism, smooth demolding of complex side wall structures is ensured; at the same time, the cavity surface is treated with DLC coating and micro-textured TiN composite treatment, which not only improves demolding performance but also ensures the smoothness of the outer surface of the tank, effectively solving the defects of uneven filling, air holes, shrinkage, difficult demolding, and surface burrs in the prior art. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the outer structure of the exhaust insert of this utility model; Figure 3 This is a schematic diagram of the outer structure of the inclined guide post of this utility model; Figure 4 This is a schematic diagram of the outer structure of the gas collection chamber of this utility model; Explanation of reference numerals in the attached drawings: 1. Upper mold assembly; 2. Lower mold assembly; 3. Side core pulling mechanism; 4. Cavity groove; 5. Core boss; 6. Closed mold cavity; 7. Diverter cone runner; 8. Sprue bushing; 9. Ingate; 10. Main water inlet channel; 11. Main water return channel; 12. Spiral cooling branch; 13. Venting groove; 14. Gas collection chamber; 15. Venting insert; 16. Slider seat; 17. Angled guide post; 18. Return spring; 19. Molding insert; 20. DLC coating; 21. Microtexture array; 22. Titanium nitride hard coating; 23. Guide rib; 24. Lubricating oil reservoir; 25. Oil seepage hole. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0018] Specific implementation examples are given below.

[0019] See Figures 1-4 This utility model provides a die-casting mold for metal packaging cans, which is described below in conjunction with the attached drawings. Figure 1 To be continued Figure 4 The structure, the connection relationships, positional relationships, mutual cooperation relationships, and overall operation process of the mold are described in detail. The structure described in this embodiment is a complete technical solution that can be actually manufactured and put into use. All key components are described in accordance with the numbers in the accompanying drawings to ensure that those skilled in the art can accurately reproduce the mold based on the contents of this specification. The overall structure of this utility model includes an upper mold assembly 1, a lower mold assembly 2, and a side core-pulling mechanism 3 disposed between the two. Under the drive of the die-casting machine, the upper mold assembly 1 and the lower mold assembly 2 perform mold closing and opening actions in the vertical direction. When the mold is closed, they form a closed mold cavity 6 for forming the overall shape of the metal packaging can. The bottom of the upper mold assembly 1 is provided with a cavity groove 4, the outline of which is completely matched with the top shape of the metal packaging can. The top of the lower mold assembly 2 is provided with a core boss 5, the shape of which is consistent with the bottom inner cavity of the metal packaging can. When the upper mold assembly 1 and the lower mold assembly 2 are closed, the cavity groove 4 and the core boss 5 together enclose and form a closed mold cavity 6. The spatial shape of this mold cavity is the final geometric shape of the metal packaging can to be formed. Inside the upper mold assembly 1, a ring-shaped distribution of flow divider cone channels 7 is embedded. The central axis of the flow divider cone channels 7 coincides with the vertical center line of the upper mold assembly 1, and its cone angle is set between 30° and 45°, preferably 35°. The inlet end of the flow divider cone channels 7 is connected to the sprue sleeve 8 of the external die-casting machine via a threaded or flanged connection, while the outlet end is connected to the closed mold cavity 6 through multiple ingates 9. The ingates 9 are arranged radially and evenly distributed along the circumference of the metal packaging can, with a number typically ranging from 4 to 8, depending on the can diameter and wall thickness. The cross-sectional height of each ingate 9 is less than three times the wall thickness of the metal packaging can. For example, if the can wall thickness is 1.2mm, the height of the ingate 9 is controlled between 0.35mm and 0.4mm. The inlet end of the ingate 9 is tangentially connected to the conical surface of the split conical runner 7, and the outlet end extends to the bottom area of ​​the closed mold cavity 6, and is inclined upwards at 5° to 8° along the height direction of the metal packaging can, for example, 6°, to avoid the molten metal directly impacting the top of the core boss 5 in the early stage of filling, thereby reducing splashing and air entrapment. The inner wall of the split conical runner 7 is mirror polished, and the surface roughness Ra value is not greater than 0.02μm, in order to reduce the flow resistance of the molten metal and ensure smooth filling. The lower mold assembly 2 integrates a cooling water system, which includes a main water inlet channel 10, a main water return channel 11, and several spiral cooling branches 12 arranged around the outer periphery of the core boss 5. The main water inlet channel 10 and the main water return channel 11 are located on both sides of the lower mold assembly 2 and are connected to the cooling circulation system through external water pipes. One end of each spiral cooling branch 12 is connected to the main water inlet channel 10, and the other end is connected to the main water return channel 11, forming a closed loop. The diameter of the spiral cooling branch 12 is 8mm to 12mm, preferably 10mm. The axial distance between adjacent spiral cooling branches 12 is 15mm to 20mm, preferably 18mm. The centerline of the spiral cooling branch 12 maintains a constant distance of 10mm to 15mm, preferably 12mm, from the outer surface of the core boss 5. This arrangement allows the cooling medium (usually water or oil) to form a uniform temperature gradient field around the core boss 5, effectively controlling the solidification sequence and preventing shrinkage defects caused by local overheating. On the parting surfaces of the upper mold assembly 1 and the lower mold assembly 2, venting grooves 13 are respectively provided in opposite directions. The venting grooves 13 are located at the corresponding positions of the highest filling area of ​​the metal packaging can, i.e., the top area of ​​the mold cavity. Their depth is 0.08 mm to 0.12 mm, preferably 0.1 mm, and their width is 3 mm to 5 mm, preferably 4 mm. The end of the venting groove 13 is connected to a gas collecting chamber 14. The volume of the gas collecting chamber 14 is 1.5 cm³ to 2.5 cm³, preferably 2.0 cm³. The inner wall of the gas collecting chamber 14 is provided with guide ribs 23. The guide ribs 23 are radially distributed along the venting direction, with a number of 6 to 12. The included angle between adjacent guide ribs 23 is 30°. The height of the guide rib 23 is 0.3 mm to 0.5 mm and the width is 1 mm to 1.5 mm. Its end is smoothly connected to the air inlet end face of the exhaust insert 15. The exhaust insert 15 is made of porous ceramic material with a porosity of 30% to 40% and an average pore diameter of 50 μm to 80 μm, preferably with a porosity of 35% and an average pore diameter of 65 μm. The exhaust insert 15 is embedded in the side wall of the upper mold assembly 1 or the lower mold assembly 2. Its outer end face is flush with the outer surface of the mold, ensuring that the gas can enter the gas collection chamber 14 through the exhaust groove 13, and then be guided by the guide rib 23 into the pore channel of the exhaust insert 15 in an orderly manner, and finally discharged into the atmosphere, while preventing the metal liquid from overflowing. The side core-pulling mechanism 3 is used to form concave structures on the side wall of the metal packaging can, such as reinforcing ribs and snap-fit ​​grooves. The side core-pulling mechanism 3 includes a slider seat 16, an inclined guide post 17, a return spring 18, and a forming insert 19. The slider seat 16 is slidably installed in the side groove of the lower mold assembly 2, and the forming insert 19 is fixedly installed on its inner end face. The shape of the forming insert 19 is perfectly matched with the concave structure of the side wall of the metal packaging can. One end of the inclined guide post 17 is fixed to the side wall of the upper mold assembly 1 by screws or interference fit, and the other end passes through the inclined hole opened on the slider seat 16. The axis of the inclined guide post 17 forms an angle of 15° to 20° with the mold opening and closing direction (i.e., the vertical direction), preferably 18°. The return spring 18 is sleeved on the lower mold assembly 2. The inclined guide post 17 has one end abutting against the outer end face of the slider seat 16, and the other end abutting against the limiting step provided on the lower mold assembly 2. During the mold closing process, the upper mold assembly 1 moves downward, driving the inclined guide post 17 to move downward. Due to the inclined surface cooperation between the inclined guide post 17 and the inclined hole of the slider seat 16, the slider seat 16 is pushed to move along the slide groove towards the center of the mold cavity, so that the molding insert 19 is embedded in the side wall area of ​​the closed mold cavity 6 and participates in the molding. During the mold opening process, the upper mold assembly 1 moves upward, and the inclined guide post 17 rises accordingly. The pushing force on the slider seat 16 disappears. At this time, the return spring 18 releases the elastic potential energy, pushing the slider seat 16 to slide outward along the slide groove, so that the molding insert 19 is separated from the side wall of the formed metal packaging can, and the demolding action is completed. To improve demolding performance and ensure the surface quality of the tank, the inner surface of the cavity groove 4 of the upper mold assembly 1 is coated with a diamond-like carbon (DLC) coating 20, with a coating thickness of 1.5 μm to 2.5 μm, preferably 2.0 μm, and a surface roughness Ra value of not more than 0.05 μm. The outer surface of the core boss 5 of the lower mold assembly 2 is provided with a micro-textured array 21, which is composed of circular pits with a diameter of 0.1 mm and a depth of 0.05 mm arranged in a square grid, with a center distance of 0.5 mm between adjacent pits. The surface of the micro-textured array 21 is further covered with a titanium nitride (TiN) hard coating 22, with a coating thickness of 1.2 μm to 2.0 μm, preferably 1.6 μm. The DLC coating 20 has the characteristics of high hardness and low coefficient of friction, while the composite structure of the micro-textured array 21 and the TiN coating 22 can store trace amounts of demolding agent and reduce the direct contact area between the molten metal and the mold surface, thereby reducing the risk of mold sticking and improving the surface finish of the inner surface of the tank. In addition, a lubrication reservoir 24 is provided between the slider seat 16 and the slide groove of the lower mold assembly 2. The lubrication reservoir 24 is located on the bottom surface of the slide groove and is distributed in a strip shape. Its length is consistent with the stroke of the slider seat 16, and is usually 30mm to 60mm. The lubrication reservoir 24 is filled with high-temperature lithium-based grease, which can work for a long time at temperatures above 200°C without failure. The bottom surface of the slider seat 16 is provided with a plurality of oil seepage holes 25. The diameter of the oil seepage holes 25 is 0.8mm to 1.2mm, preferably 1.0mm. They are arranged at equal intervals along the sliding direction of the slider seat 16, with a spacing of 20mm to 25mm, preferably 22mm. During the reciprocating motion of the slider seat 16, the grease continuously seeps out through the oil seepage holes 25, forming an oil film on the sliding contact surface, effectively reducing frictional resistance and preventing metal adhesion or jamming caused by high temperature. In the actual die-casting production process, the upper mold assembly 1 and the lower mold assembly 2 are first installed on the moving mold and fixed mold base plates of the die-casting machine, and the cooling water circuit and the sprue bushing 8 are connected. The die-casting machine is started to close the mold. The upper mold assembly 1 moves downward, the inclined guide post 17 pushes the slider seat 16 to move inward, the forming insert 19 is embedded into the side wall of the mold cavity, and at the same time the cavity groove 4 and the core boss 5 close to form a closed mold cavity 6. Subsequently, the die-casting machine injects molten metal (such as aluminum alloy) into the diversion cone channel 7 through the sprue bushing 8. After being diverted, the molten metal flows through multiple internal gating channels. The nozzle 9 smoothly fills the closed mold cavity 6 along the axial direction of the tank body; during this process, the venting groove 13 and the venting insert 15 work together to discharge the gas in the mold cavity to prevent the formation of air holes; the cooling medium in the spiral cooling branch 12 carries away the heat synchronously to control the solidification rate; after the molten metal has completely solidified, the die casting machine opens the mold, the upper mold assembly 1 moves upward, the return spring 18 pushes the slider seat 16 to return to its original position, the forming insert 19 disengages from the side wall of the tank body, and then the ejection mechanism ejects the formed metal packaging can from the core boss 5 to complete one forming cycle; In the above structure, the geometric parameters of the diversion cone channel 7 and the multi-point ingate 9, the spatial layout of the spiral cooling branch 12, the size matching of the venting groove 13 and the venting insert 15, the angle of the inclined guide post 17 and the stiffness of the return spring 18 of the side core pulling mechanism 3, and the specific parameters of the surface coating and microtexture are all indispensable technical features for achieving the purpose of this utility model. They must work together to solve the problems of uneven filling, porosity, shrinkage, difficulty in demolding, and surface burrs in the prior art. In order to enable those skilled in the art to fully understand and implement this utility model, the specific implementation principle of this utility model is further supplemented below in conjunction with a specific application scenario. When producing aluminum alloy beverage packaging cans with a diameter of 65mm, a height of 120mm, and a wall thickness of 1.2mm, the upper mold assembly 1 is first installed on the fixed mold base plate of the die-casting machine, and the lower mold assembly 2 is installed on the moving mold base plate. The external cooling circulation system is connected to the main water inlet channel 10 and the main water return channel 11 via quick-connect couplings. At the same time, the sprue sleeve 8 is connected to the nozzle of the die-casting machine. The die-casting machine is started to perform the mold closing action. The upper mold assembly 1 moves downward in the vertical direction, driving the inclined guide post 17 fixed to its side wall to move downward in sync. Since the inclined guide post 17 is inserted into the inclined hole of the slider seat 16 at an 18° angle, it applies a horizontal component force to the slider seat 16 during its downward movement, pushing the slider seat 16 to slide along the side groove of the lower mold assembly 2 toward the center of the mold cavity, so that the molding insert 19 is accurately embedded into the side wall area of ​​the closed mold cavity 6, completing the molding and positioning of the snap-fit ​​groove on the outside of the can; at the same time, the cavity groove 4 at the bottom of the upper mold assembly 1 and the core boss 5 at the top of the lower mold assembly 2 are completely closed, forming a closed mold cavity 6 with a contour that precisely matches the geometry of the can; Subsequently, the die-casting machine injects molten aluminum alloy at 680℃ into the flow channel 7 through the sprue sleeve 8 at a specific pressure of 55MPa. The 35° cone angle of the flow channel 7, together with the mirror-polished inner wall (Ra≤0.02μm), ensures that the molten metal is evenly distributed along the cone surface. The molten metal enters the closed mold cavity 6 through eight circumferentially distributed ingates 9. The cross-sectional height of each ingate 9 is 0.38mm (approximately 31.7% of the 1.2mm thickness of the tank wall). Its outlet end is inclined upward at 6° from the bottom of the mold cavity, guiding the molten metal to fill smoothly from bottom to top along the axial direction of the tank, avoiding splashing or air entrapment caused by the high-speed molten metal directly impacting the top of the core boss 5. During this filling process, the gas accumulated in the top area of ​​the mold cavity is quickly discharged through the venting groove 13 with a depth of 0.1 mm and a width of 4 mm on the parting surface. The gas first enters the gas collecting chamber 14 with a volume of 2.0 cm³, and is then guided by six radially distributed guide ribs 23 with an included angle of 30°, and evenly dispersed to the air inlet end face of the venting insert 15. Since the venting insert 15 is made of porous ceramic material with a porosity of 35% and an average pore size of 65 μm, the gas can be smoothly discharged into the atmosphere through its internal interconnecting pores, while the molten metal is blocked at the inlet of the venting groove 13 due to surface tension and cannot enter the gas collecting chamber 14, thereby achieving efficient venting and no overflow. After the molten metal is filled, the cooling system is started simultaneously. Cooling water flows into eight spiral cooling branches 12 arranged around the outer periphery of the core boss 5 through the self-inlet channel 10. Each branch has a pipe diameter of 10mm, the axial distance between adjacent branches is 18mm, and the distance from the center line of the branch to the outer surface of the core boss 5 is always 12mm. The cooling water flows along the spiral path, forming a continuous and uniform annular cooling zone around the core boss 5, so that the bottom and side wall areas of the tank solidify synchronously at a controllable rate, avoiding shrinkage defects caused by slow local heat dissipation. After the holding time reaches the set value (usually 8 seconds), the die casting machine performs the mold opening action. The upper mold assembly 1 moves upward, the inclined guide post 17 disengages from the inclined hole of the slider seat 16, the return spring 18 releases the pre-compressed elastic potential energy, and pushes the slider seat 16 to return outward along the slide groove, so that the forming insert 19 can be smoothly removed from the snap-fit ​​groove on the side wall of the tank. At the same time, the ejection mechanism moves to push the solidified tank away from the core boss 5. Throughout the entire mold closing-filling-cooling-opening cycle, the 2.0μm thick DLC coating 20 covering the inner surface of the cavity groove 4 of the upper mold assembly 1 significantly reduces the adhesion between the outer surface of the can and the mold due to its high hardness (≥20GPa) and low coefficient of friction (≤0.1). The micro-textured array 21 on the surface of the core boss 5 of the lower mold assembly 2 consists of circular pits with a diameter of 0.1mm and a depth of 0.05mm arranged orthogonally at a center distance of 0.5mm. The 1.6μm thick titanium nitride hard coating 22 covering its surface not only improves wear resistance but also... The recess can store a small amount of release agent, which forms a lubricating film at high temperature, reducing the direct contact area between the molten metal and the mold, thereby inhibiting sticking and ensuring that the surface roughness Ra of the inner surface of the tank is Ra≤0.8μm; in addition, during the reciprocating motion of the slider seat 16, the oil seepage holes 25 (diameter 1.0mm, spacing 22mm) provided on its bottom surface continuously draw high-temperature lithium-based grease from the lubrication oil reservoir 24, forming a dynamic oil film on the contact surface between the slider seat 16 and the groove, effectively maintaining the smooth sliding of the side core pulling mechanism 3 under working conditions above 200℃, and preventing jamming caused by thermal expansion; The coordinated operation of the above structural parameters and running sequence enables the molten metal to achieve axial sequential filling, uniform heat dissipation and solidification, efficient venting and impurity removal, and non-destructive demolding within the closed mold cavity 6. This fundamentally solves the process defects that easily occur in the die casting process of thin-walled deep-cavity metal packaging cans, such as filling disorder, porosity, shrinkage porosity, demolding scratches, and surface burrs. All contents not described in detail in the specification are existing technologies known to those skilled in the art, and the model parameters of each device are not specifically limited. Conventional die casting equipment and control systems can be used to achieve this. Electrical control components not mentioned in this technical solution are not shown in the figure because they are existing technologies, and will not be described in detail.

[0020] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A die-casting mold for metal packaging cans, comprising an upper mold assembly (1), a lower mold assembly (2), and a side core-pulling mechanism (3) disposed between the two, characterized in that: The bottom of the upper mold assembly (1) is provided with a cavity groove (4) that matches the top contour of the metal packaging can, and the top of the lower mold assembly (2) is provided with a core boss (5) that matches the bottom contour of the metal packaging can. The cavity groove (4) and the core boss (5) together enclose the mold in the mold-closed state to form a closed mold cavity (6) for molding the overall shape of the metal packaging can. The upper mold assembly (1) is embedded with a ring-shaped distribution of flow divider cone channels (7). The inlet end of the flow divider cone channel (7) is connected to the sprue sleeve (8) of the external die-casting machine. The outlet end is connected to the closed mold cavity (6) through multiple radially arranged inlet gates (9). Each inlet gate (9) is evenly distributed along the circumference of the metal packaging can, and the cross-sectional height of the inlet gate (9) is less than one-third of the wall thickness of the metal packaging can. The outlet direction of the inlet gate (9) is consistent with the flow direction of the molten metal in the mold cavity.

2. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The lower mold assembly (2) is equipped with a cooling water channel system, which includes a main water inlet channel (10), a main water return channel (11), and several spiral cooling branches (12) arranged around the outer periphery of the core boss (5). One end of each spiral cooling branch (12) is connected to the main water inlet channel (10), and the other end is connected to the main water return channel (11). The diameter of the spiral cooling branch (12) is 8mm to 12mm, the axial distance between adjacent spiral cooling branches (12) is 15mm to 20mm, and the distance between the center line of the spiral cooling branch (12) and the outer surface of the core boss (5) is 10mm to 15mm.

3. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The upper mold assembly (1) and the lower mold assembly (2) are respectively provided with venting grooves (13) that are aligned with each other. The venting grooves (13) are located at the corresponding positions of the highest filling area of ​​the metal packaging can. The depth of the venting grooves (13) is 0.08 mm to 0.12 mm and the width is 3 mm to 5 mm. The end of the venting grooves (13) is connected to the gas collection chamber (14). The gas collection chamber (14) is connected to the atmosphere through the venting insert (15). The venting insert (15) is made of porous ceramic material with a porosity of 30% to 40% and an average pore diameter of 50 μm to 80 μm. The venting insert (15) is embedded in the side wall of the upper mold assembly (1) or the lower mold assembly (2), and its outer end face is flush with the outer surface of the mold.

4. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The side core-pulling mechanism (3) includes a slider seat (16), an inclined guide post (17), and a return spring (18). The slider seat (16) is slidably installed in the side groove of the lower mold assembly (2). The inner end face of the slider seat (16) is provided with a molding insert (19) that matches the concave structure of the side wall of the metal packaging can. One end of the inclined guide post (17) is fixed to the side wall of the upper mold assembly (1), and the other end passes through the inclined hole on the slider seat (16). The axis of the inclined guide post (17) forms an angle of 15° to 20° with the mold opening and closing direction. The return spring (18) is sleeved on the outside of the inclined guide post (17), with one end abutting against the slider seat (16) and the other end abutting against the limiting step of the lower mold assembly (2).

5. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The inner surface of the cavity groove (4) of the upper mold assembly (1) is coated with a diamond-like carbon coating (20) with a coating thickness of 1.5μm to 2.5μm and a surface roughness Ra value of no more than 0.05μm; the outer surface of the core boss (5) of the lower mold assembly (2) is provided with a micro-texture array (21), the micro-texture array (21) is a circular pit with a diameter of 0.1mm and a depth of 0.05mm, the pits are arranged in a square grid, the center distance between adjacent pits is 0.5mm, and the surface of the micro-texture array (21) is covered with a titanium nitride hard coating (22) with a thickness of 1.2μm to 2.0μm.

6. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The central axis of the diversion cone channel (7) coincides with the vertical center line of the upper mold assembly (1). The cone angle of the diversion cone channel (7) is 30° to 45°, and the surface roughness Ra value of its inner wall is not greater than 0.02μm. The inlet end of each ingate (9) is tangentially connected to the cone surface of the diversion cone channel (7), and the outlet end extends to the bottom area of ​​the closed mold cavity (6) and tilts upward at 5° to 8° along the height direction of the metal packaging can.

7. The die-casting mold for metal packaging cans according to claim 3, characterized in that: The volume of the gas collection chamber (14) is 1.5 cm³ to 2.5 cm³, and its inner wall is provided with guide ribs (23). The guide ribs (23) are radially distributed along the exhaust direction. The height of the guide ribs (23) is 0.3 mm to 0.5 mm, the width is 1 mm to 1.5 mm, the included angle between adjacent guide ribs (23) is 30°, and the end of the guide ribs (23) is smoothly connected to the air intake end face of the exhaust insert (15).

8. The die-casting mold for metal packaging cans according to claim 4, characterized in that: A lubrication reservoir (24) is provided between the slider seat (16) and the slide groove of the lower mold assembly (2). The lubrication reservoir (24) is located on the bottom surface of the slide groove and is distributed in a strip shape. Its length is consistent with the stroke of the slider seat (16). The lubrication reservoir (24) is filled with grease. The bottom surface of the slider seat (16) is provided with oil seepage holes (25) corresponding to the lubrication reservoir (24). The diameter of the oil seepage holes (25) is 0.8mm to 1.2mm. They are arranged at equal intervals along the sliding direction of the slider seat (16) with a spacing of 20mm to 25mm.

9. The die-casting mold for metal packaging cans according to claim 2, characterized in that: The spiral cooling branch (12) is arranged in a spiral shape around the outer periphery of the core boss (5), and its path extends along the axial direction of the core boss (5). Each spiral cooling branch (12) is evenly distributed in the circumferential direction.

10. The die-casting mold for metal packaging cans according to claim 1, characterized in that: The number of ingates (9) is 4 to 8, and each ingate (9) is distributed at an equal angle along the circumferential direction at the discharge end of the split cone channel (7).

Images