Two-color injection mold and injection molding method for producing a milk powder can lid

Abstract

The present application relates to injection mold technical field, especially in a kind of for producing milk powder tank cover's double-color injection mold and injection molding method.The mold realizes hard glue and soft glue synchronous injection molding by double forming station coordination rotating mechanism, gradient type water circulation cooling mechanism is matched, realizes differentiation temperature control, rotating process cooling water is uninterrupted circulation, while integrating waterway self-cleaning, leakage detection and waste heat recovery function, the problems such as traditional double-color injection molding production efficiency is low, product forming defect is many, cooling system function single etc.are solved, the forming precision, sealing performance and production efficiency of milk powder tank cover are greatly improved, and production energy consumption and maintenance cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, and in particular to a two-color injection mold and injection method for producing milk powder can lids. Background Technology

[0002] As a core component of infant formula packaging, the two-tone milk powder can lid employs a dual-material structure design, with an outer hard rubber layer providing structural support and an inner soft rubber layer ensuring sealing performance. This places extremely high demands on the product's molding precision, sealing performance, dimensional consistency, and production efficiency. Currently, the injection molding production of two-tone milk powder can lids mostly adopts a two-stage injection molding process, requiring the mold to be opened and closed twice, and a robotic arm to adjust the mold orientation or rotate the entire mold to complete the two-tone molding. This not only results in bulky equipment and a large production space, but also a cumbersome production process and low production efficiency.

[0003] Meanwhile, existing two-color injection molds still have many technical defects in practical applications. For example, the cooling system mostly adopts a uniform water circuit design, which cannot perform differentiated gradient temperature control according to the different material properties and molding process requirements of soft and hard rubber. This can easily lead to problems such as inconsistent product molding shrinkage, warping deformation, and obvious weld lines, making it difficult to guarantee the sealing performance and dimensional accuracy of milk powder can lids. Moreover, during the rotation and repositioning of the front mold core, the cooling water circuit is prone to circulation interruption, making it impossible to achieve continuous cooling. This not only prolongs the product molding cycle but also affects the stability of batch molding quality. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a two-color injection mold for producing milk powder can lids, comprising:

[0005] A first mold shell, with a front mold core embedded inside the first mold shell;

[0006] The second mold shell is slidable in the horizontal left and right direction and is located on the right side of the first mold shell. The second mold shell has a rear mold core embedded inside. After the front mold core and the rear mold core are molded together, they form a molding cavity for the two-color milk powder can lid. The front mold core has two molding stations that are centrally symmetrically distributed.

[0007] Both the soft rubber hot runner assembly and the hard rubber hot runner assembly are installed inside the first mold shell, and the two are arranged vertically in space, respectively corresponding to and connected to the two molding stations of the front mold core.

[0008] An ejection mechanism is set inside the first mold shell and connected to the front mold core for synchronously ejecting the front mold core, the molded two-color milk powder can lid, and the soft rubber gate.

[0009] A rotary positioning mechanism is provided inside the first mold shell and fixedly connected to the front mold core. It is used to drive the front mold core to rotate and position after it is pushed out to the right, so that the spatial positions of the two molding stations can be interchanged.

[0010] A gradient water circulation cooling system is installed inside the first mold shell, the front mold core, and the rear mold core. It includes a front mold cooling module, a rear mold cooling module, a cooling water control module, and a waste heat recovery module. The front mold cooling module is adapted to the front mold core, and the rear mold cooling module is adapted to the rear mold core. Both are connected to the cooling water control module. The waste heat recovery module is connected to the outlet of the cooling water control module to realize the recovery and reuse of the cooling water's thermal energy.

[0011] In some feasible embodiments, the front mold cooling module includes a first cooling water channel, a second cooling water channel, a rotary annular connecting interface, and independent cooling branches for each workstation. The first cooling water channel is located inside the sliding seat, and the second cooling water channel is located along the axis of the rotating spindle. The two are connected by the rotary annular connecting interface. Double-layer sealing rings are provided on both sides of the rotary annular connecting interface. There are two sets of independent cooling branches for each workstation, which are adapted to the two forming workstations of the front mold core respectively. The water pipe diameter and water flow rate of the two sets of independent cooling branches for each workstation can be adjusted independently.

[0012] In some feasible embodiments, the rear mold cooling module includes a rear mold main cooling water channel, a mold cavity fitting cooling flow hole and a heat insulation layer. The mold cavity fitting cooling flow hole is opened in the rear mold core on the side close to the molding cavity and is connected to the rear mold main cooling water channel. The heat insulation layer is disposed at the mating surface between the rear mold core and the second mold shell to reduce the loss of cold energy of the rear mold cooling module.

[0013] In some feasible embodiments, the cooling water control module includes a constant temperature water storage tank, a variable frequency booster pump, a water circuit switching valve group, an automatic cleaning component, and a leakage detection component. The variable frequency booster pump is connected to the constant temperature water storage tank and is used to adjust the delivery pressure and flow rate of the cooling water. The water circuit switching valve group is connected to the front mold cooling module and the rear mold cooling module respectively, and is used to realize independent on / off and precise flow adjustment of the cooling water circuits of the front mold and the rear mold. The automatic cleaning component is used to automatically flush and descale the water circuits of the entire water circulation cooling system. The leakage detection component is set at each connection node of the water circuit and is used to detect the leakage status of the water circuit in real time and issue an early warning signal.

[0014] In some feasible embodiments, the automatic cleaning assembly includes a high-pressure flushing pump, a descaling agent metering storage box, and a drain valve assembly. The high-pressure flushing pump is connected to a constant temperature water tank. The descaling agent metering storage box is connected to the water inlet of the high-pressure flushing pump and can add descaling agent meteredly according to cleaning needs. The drain valve assembly is located at the end of each cooling water circuit and is used to discharge the flushed wastewater and impurities.

[0015] In some feasible embodiments, the leakage detection component includes a pressure sensing module, a liquid level sensing module, and an audible and visual alarm module. The pressure sensing module is installed on the delivery pipeline of each cooling water circuit, and the liquid level sensing module is installed in the liquid receiving tank of the rotary annular connecting interface and the double-layer sealing rubber ring. Both the pressure sensing module and the liquid level sensing module are electrically connected to the audible and visual alarm module.

[0016] In some feasible embodiments, the waste heat recovery module includes a heat exchange storage tank, a tubular heat exchange component, and a hot water delivery pipeline. The tubular heat exchange component is connected to the outlet of the cooling water control module and the heat exchange storage tank, respectively, and is used to transfer the waste heat in the cooling water to the cold water in the heat exchange storage tank. The hot water delivery pipeline is connected to the heat exchange storage tank and is used to deliver the preheated hot water to the heating equipment of the injection molding equipment.

[0017] In some feasible embodiments, the two sets of independent cooling branches of the front mold cooling module are adapted to the soft rubber injection molding station and the hard rubber injection molding station, respectively. The water flow rate of the cooling branch corresponding to the soft rubber injection molding station is higher than that of the cooling branch corresponding to the hard rubber injection molding station, and the cooling water channel of the soft rubber injection molding station is set to fit the inner side wall of the soft rubber molding area of ​​the milk powder can lid.

[0018] In some feasible embodiments, the rotary shifting mechanism includes a rotary spindle, a sliding bushing, a transmission gear, a first drive cylinder, and a meshing rack. The rotary spindle is rotatably mounted inside a first mold shell, with one end fixedly connected to the front mold core and the other end fitted with a sliding bushing that can slide along its axial direction. The transmission gear is fixedly fitted on the sliding bushing, and the output end of the first drive cylinder is fixedly connected to the meshing rack. The transmission gear meshes with the meshing rack.

[0019] In some feasible embodiments, the ejection mechanism includes a second drive cylinder, a sliding seat, a third drive cylinder, and an ejector pin assembly. The output end of the second drive cylinder is fixedly connected to the sliding seat, and the sliding seat is rotatably connected to the end of the rotating spindle away from the front mold core. The third drive cylinder is fixed inside the first mold shell, and its output end ejects the soft rubber gate through the ejector pin assembly.

[0020] The present invention also provides an injection molding method for producing a two-color injection mold for milk powder can lids, which can be implemented on the above-mentioned mold, including the following steps:

[0021] S100, start the gradient water circulation cooling system, the variable frequency booster water pump of the cooling water control module starts, and delivers the cooling water in the constant temperature water tank to the front mold cooling module and the rear mold cooling module. The flow rate of the cooling water in the front mold and the rear mold is adjusted by the water circuit switching valve group so that the soft rubber injection station, the hard rubber injection station and the rear mold core reach the preset cooling temperature and water flow rate respectively.

[0022] S200: Hard plastic raw material and soft plastic raw material are added to the barrel of the corresponding injection molding equipment through an automatic feeding machine. After the raw material is plasticized, the mold is closed and injection molding is performed. Hard plastic is injected at the molding station of the lower half of the front mold core to form the can lid base, and soft plastic is injected at the molding station of the upper half of the front mold core to form the sealing layer, thus obtaining the finished product of the two-color milk powder can lid. During the injection molding process, the gradient water circulation cooling system continuously performs differentiated gradient cooling, and the waste heat recovery module simultaneously recovers the waste heat of the cooling water.

[0023] S300, after injection molding and pressure holding are completed, the mold is opened, so that the first mold shell and the second mold shell are separated from each other, and the front mold core and the rear mold core are separated. During the mold opening process, the front mold cooling module keeps the cooling water circulating continuously through the rotary annular connecting interface.

[0024] S400, the second and third drive cylinders start synchronously to eject the front mold core, and eject the two-color milk powder can lid finished product and soft rubber gate formed in the upper part of the front mold core. The robot arm extends into the part removal area to remove the two-color milk powder can lid finished product and soft rubber gate.

[0025] S500, the first drive cylinder drives the meshing rack to move, and through the gear and rack meshing transmission, it drives the front mold core to rotate 180°. During the rotation, the rotating annular connecting interface of the front mold cooling module rotates synchronously with the rotating main shaft to keep the cooling water circulation uninterrupted. The cooling parameters of the two sets of independent cooling branches of the workstation are switched synchronously as the position of the molding workstation is changed.

[0026] S600, the second and third drive cylinders move in opposite directions, driving the ejector pin assembly and the front mold core to reset, closing the mold again and repeating steps S200-S500 to achieve continuous injection molding production of two-color milk powder can lids.

[0027] When the S700 is shut down or undergoes regular maintenance, the automatic cleaning component is activated to add a measured amount of descaling agent to the cooling water circuit and perform high-pressure flushing using a high-pressure flushing pump. The flushed wastewater is discharged through the drain valve assembly, and at the same time, the leak detection component performs comprehensive leak detection on each node of the water circuit.

[0028] In some feasible embodiments, during steps S100-S600, the leakage detection component monitors the water circuit operation status in real time throughout the process. If abnormal water circuit pressure or excessive liquid level in the receiving tank is detected, the audible and visual alarm module immediately issues an audible and visual warning. At the same time, the cooling water control module controls the variable frequency booster pump to stop and closes the water circuit switching valve group.

[0029] In some feasible embodiments, in step S200, during the injection molding process, the flow rate of cooling water is gradually adjusted by a variable frequency booster water pump according to the molding progress of the milk powder can lid. Low flow rate cooling is used in the early stage of injection molding, and high flow rate cooling is used in the later stage of injection molding to achieve stepped cooling temperature control.

[0030] The beneficial effects of this invention are as follows: The structure is compact and reasonable. Through a dual-molding station combined with a rotary switching mechanism, hard and soft rubber injection molding can be performed simultaneously. A single mold closing operation can simultaneously complete the injection molding of the can lid base (hard rubber) and the finished can lid (soft rubber), eliminating the need for additional robotic arms for switching. This significantly reduces the production cycle and improves production efficiency. Simultaneously, the overall equipment size is smaller, saving production space. The gradient water circulation cooling system can achieve differentiated gradient cooling for different molding requirements of soft and hard rubber, precisely adapting to the molding process characteristics of different materials. This effectively reduces molding defects such as product warpage and weld lines, improving the dimensional accuracy and sealing performance of the milk powder can lid. Furthermore, the rotary annular connecting interface ensures uninterrupted circulation of cooling water during the rotation and switching of the front mold core, guaranteeing continuous cooling throughout the production process and further improving the stability of product batch quality. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0032] Figure 1 This is a schematic diagram of the overall three-dimensional structure of a two-color injection mold provided in an embodiment of the present invention;

[0033] Figure 2 A three-dimensional structural schematic diagram of the first mold shell portion provided in an embodiment of the present invention;

[0034] Figure 3 A three-dimensional structural schematic diagram of the second mold shell portion provided in an embodiment of the present invention;

[0035] Figure 4 A cross-sectional structural diagram of a two-color injection mold provided in an embodiment of the present invention;

[0036] Figure 5A schematic diagram of the cooperative structure of the rotating mechanism and the ejection mechanism provided in an embodiment of the present invention;

[0037] Figure 6 This is an exploded view of the rotating spindle and sliding seat portion provided in an embodiment of the present invention;

[0038] Figure 7 A system structure block diagram of the gradient water circulation cooling mechanism provided in an embodiment of the present invention;

[0039] Figure 8 A system structure block diagram of the cooling water control module and automatic cleaning component provided in the embodiments of the present invention;

[0040] Figure 9 A process flow diagram of the injection molding method for a two-color injection mold provided in an embodiment of the present invention.

[0041] Reference numerals: First mold shell 1, front mold core 11, molding station 111, second mold shell 2, rear mold core 21, second drive cylinder 51, sliding seat 52, third drive cylinder 53, ejector pin assembly 54, rotating spindle 61, sliding bushing 62, transmission gear 63, first drive cylinder 64, meshing rack 65, front mold cooling module 71, first cooling water channel 711, second cooling water channel 712, rotary annular connecting interface 713, independent cooling branch for the station 714, double Layer sealing ring 715, rear mold cooling module 72, rear mold main cooling water channel 721, mold cavity fitting cooling flow hole 722, heat insulation layer 723, cooling water regulation module 73, constant temperature water storage tank 731, variable frequency booster water pump 732, water channel switching valve group 733, high pressure flushing pump 7341, descaling agent quantitative storage box 7342, drain valve group 7343, waste heat recovery module 74, heat exchange water storage tank 741, tubular heat exchange component 742, hot water delivery pipeline 743. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] See Figures 1 to 6The diagram illustrates a two-color injection mold for producing milk powder can lids, comprising a first mold shell 1, a second mold shell 2, a soft rubber hot runner assembly, a hard rubber hot runner assembly, an ejection mechanism, a rotary positioning mechanism, and a gradient water circulation cooling system. The first mold shell 1 is the fixed-side base of the mold, with a front mold core 11 embedded inside. The front mold core 11 is one of the core molding components of the two-color milk powder can lid. The second mold shell 2 is the movable-side base of the mold, capable of sliding horizontally to the right of the first mold shell 1. A rear mold core 21 is embedded inside the second mold shell 2. In the closed state, the front mold core 11 and the rear mold core 21 are tightly fitted together, forming the molding cavity of the two-color milk powder can lid, providing a sealed cavity for the injection molding of the milk powder can lid. The front mold core 11 has two centrally symmetrical molding stations 111. The cavity structures of the two molding stations 111 are completely identical, and they can respectively complete the injection molding of hard plastic parts and soft plastic parts. The continuous operation of two-color molding can be achieved by interchangeing the stations.

[0044] Both the soft rubber hot runner assembly and the hard rubber hot runner assembly are installed inside the first mold shell 1, and they are arranged vertically in space. They are connected to the two molding stations 111 of the front mold core 11 respectively. The mutually perpendicular arrangement can completely avoid the two hot runners, avoiding pipe interference during injection molding. At the same time, they do not need to rotate with the front mold core 11, which greatly simplifies the mold structure and reduces the overall size of the equipment.

[0045] Reference Figure 6 As shown, the ejection mechanism is located inside the first mold shell 1 and is connected to the front mold core 11 for transmission. It is used to eject the front mold core 11, the molded two-color milk powder can lid, and the soft rubber gate simultaneously, providing operating space for subsequent station rotation and product removal. The ejection mechanism includes a second drive cylinder 51, a sliding seat 52, a third drive cylinder 53, and an ejector pin assembly 54. The output end of the second drive cylinder 51 is fixedly connected to the sliding seat 52. The sliding seat 52 is rotatably connected to the end of the rotating spindle 61 away from the front mold core 11. When the second drive cylinder 51 drives the sliding seat 52 to make left and right linear reciprocating motion, the rotating spindle 61 can drive the front mold core 11 to move left and right synchronously, realizing the ejection and reset of the front mold core 11. The third drive cylinder 53 is fixedly installed inside the first mold shell 1, and its output end is connected to the ejector pin assembly 54. The ejector pin assembly 54 ejects the soft rubber gate to avoid gate residue affecting subsequent injection molding operations. The design of the sliding bushing 62, which can slide along the axial direction of the rotating main shaft 61, makes the rotational action of the rotary switching mechanism and the translational action of the ejection mechanism completely independent and do not interfere with each other, thus ensuring the stability and smoothness of mold operation.

[0046] Reference Figure 6As shown, the rotary positioning mechanism is located inside the first mold shell 1 and fixedly connected to the front mold core 11. It is used to drive the front mold core 11 to rotate and reposition after it is pushed out to the right, thus exchanging the spatial positions of the two molding stations 111. This rotates the semi-finished product station (where hard plastic injection molding is completed) to the soft plastic injection station, and simultaneously rotates the finished product station (where two-color injection molding is completed) to the part removal position, enabling one finished product injection to be completed in a single cycle, significantly improving production efficiency. The rotary positioning mechanism includes a rotary spindle 61, a sliding bushing 62, and a transmission gear 6. 3. The first drive cylinder 64 and the meshing rack 65, and the rotating main shaft 61 are rotatably installed in the first mold shell 1. One end of the rotating main shaft 61 is fixedly connected to the front mold core 11, which can drive the front mold core 11 to rotate synchronously. The other end of the rotating main shaft 61 is fitted with a sliding bushing 62 that can slide along its axial direction. The inner wall of the sliding bushing 62 and the outer wall of the rotating main shaft 61 are matched by a circumferential limiting structure, so that the sliding bushing 62 can slide along the axial direction of the rotating main shaft 61, and at the same time drive the rotating main shaft 61 to rotate synchronously in the circumferential direction. The transmission gear 63 is fixedly sleeved on the outer wall of the sliding bushing 62. The output end of the first drive cylinder 64 is fixedly connected to the meshing rack 65. The transmission gear 63 meshes with the meshing rack 65. When the first drive cylinder 64 drives the meshing rack 65 to perform linear reciprocating motion, the meshing transmission between the meshing rack 65 and the transmission gear 63 can drive the sliding bushing 62 to rotate. In turn, the sliding bushing 62 drives the rotating spindle 61 and the front mold core 11 to complete a 180° rotation, thereby realizing the position exchange of the two molding stations 111.

[0047] Reference Figure 7 As shown, a gradient water circulation cooling system is installed inside the first mold shell 1, the front mold core 11, and the rear mold core 21. It is used for differentiated temperature cooling based on material compatibility throughout the injection molding process and enables continuous circulation of cooling water during the rotation and repositioning of the front mold core 11. It also integrates water circuit self-cleaning, real-time leakage detection, and waste heat recovery functions, providing stable, efficient, and safe cooling for the entire mold injection process. The gradient water circulation cooling system includes a front mold cooling module 71, a rear mold cooling module 72, a cooling water control module 73, and a waste heat recovery module 74. The front mold cooling module 71 is adapted to the front mold core 11 and provides targeted cooling for the two molding stations 111 of the front mold core 11. The rear mold cooling module 72 is adapted to the rear mold core 21 and provides uniform cooling for the rear mold core 21. Both are connected to the cooling water control module 73, which provides cooling water uniformly and controls the cooling parameters separately. The waste heat recovery module 74 is connected to the outlet of the cooling water control module 73, which can recover and utilize the waste heat contained in the cooling water after heat exchange, realize the recycling of energy, and reduce production energy consumption.

[0048] In some feasible embodiments, refer to Figure 2As shown, the front mold cooling module 71 includes a first cooling water channel 711, a second cooling water channel 712, a rotary annular connecting interface 713, and an independent cooling branch 714 for each workstation. The first cooling water channel 711 is located inside the sliding seat 52 and moves synchronously left and right with the sliding seat 52, but does not rotate with the rotating spindle 61. The second cooling water channel 712 is located along the axis of the rotating spindle 61 and rotates and moves left and right synchronously with the rotating spindle 61. The first cooling water channel 711 and the second cooling water channel 712 are connected through the rotary annular connecting interface 713. The rotary annular connecting interface 713 adopts a coaxial annular flow channel design, which can maintain the connection between the first cooling water channel 711 and the second cooling water channel 712 during the circumferential rotation of the rotating spindle 61, thereby realizing uninterrupted circulation of cooling water during the rotation and repositioning of the front mold core 11 and ensuring the continuity of the cooling process.

[0049] Reference Figure 6 As shown, double-layer sealing rings 715 are provided on both sides of the rotary annular connecting interface 713. The double-layer sealing rings 715 can achieve double sealing protection in the rotation state, greatly reducing the risk of water leakage and ensuring the sealing of the water connection. There are two sets of independent cooling branches 714 for each station, which are adapted to the two molding stations 111 of the front mold core 11 respectively. The water pipe diameter and water flow rate of the two sets of independent cooling branches 714 can be adjusted independently. Independent cooling parameters can be set for the injection molding material characteristics of the two molding stations 111 respectively, so as to achieve differentiated gradient cooling and meet the molding cooling requirements of different materials in two-color injection molding.

[0050] In some feasible embodiments, refer to Figure 3 and Figure 4 As shown, the rear mold cooling module 72 includes a rear mold main cooling water channel 721, a cavity-fitting cooling flow hole 722, and a heat insulation layer 723. The cavity-fitting cooling flow hole 722 is located inside the rear mold core 21 on the side facing the molding cavity. Its flow path is completely fitted with the contour of the molding cavity, maximizing its proximity to the injection melt, improving heat exchange efficiency, ensuring uniform cooling of the rear mold core 21, and avoiding product deformation caused by uneven local cooling. The cavity-fitting cooling flow hole 722 is connected to the rear mold main cooling water channel 721, which uniformly supplies cooling water. The heat insulation layer 723 is located at the contact surface between the rear mold core 21 and the second mold shell 2. It is made of a low thermal conductivity material and effectively isolates heat transfer between the rear mold core 21 and the second mold shell 2, reducing the loss of cold energy from the rear mold cooling module 72 to the second mold shell 2, improving cooling efficiency, and reducing cooling energy consumption.

[0051] In some feasible embodiments, refer to Figure 7As shown, the cooling water control module 73 includes a constant temperature water storage tank 731, a variable frequency booster pump 732, a water circuit switching valve group 733, an automatic cleaning component, and a leakage detection component. The constant temperature water storage tank 731 is used to store and regulate the temperature of the cooling water, providing a stable temperature for the cooling system. The variable frequency booster pump 732 is connected to the constant temperature water storage tank 731 and is used to adjust the delivery pressure and flow rate of the cooling water. It can flexibly adjust the cooling water delivery parameters according to different stages of the injection molding process to adapt to different cooling needs.

[0052] The water circuit switching valve assembly 733 is connected to the front mold cooling module 71 and the rear mold cooling module 72 respectively, and is used to realize the independent on / off and precise flow regulation of the cooling water circuits of the front mold and the rear mold. It can control the on / off and flow rate of the cooling water circuits of the two molding stations 111 of the front mold core 11 and the rear mold core 21 respectively, and realize independent temperature control of multiple areas. The automatic cleaning component is used to automatically flush and descale the water circuits of the entire water circulation cooling system. The water circuit cleaning can be completed without manual disassembly of the mold, reducing the difficulty of mold maintenance. The leakage detection component is set at each connection node of the water circuit to detect the leakage status of the water circuit in real time and issue an early warning signal to ensure the safe operation of the cooling system.

[0053] In some feasible embodiments, refer to Figure 8 As shown, the automatic cleaning assembly includes a high-pressure flushing pump 7341, a descaling agent metering reservoir 7342, and a drain valve assembly 7343. The high-pressure flushing pump 7341 is connected to a constant-temperature water tank 731, providing high-pressure flushing water to powerfully flush scale and impurities from the inner walls of the water channels. The descaling agent metering reservoir 7342 is connected to the inlet of the high-pressure flushing pump 7341, allowing for the metered addition of descaling agent according to cleaning needs. This, combined with the high-pressure water flow, dissolves stubborn scale from the inner walls of the water channels, enhancing the cleaning effect. The drain valve assembly 7343 is located at the end of each cooling water channel, used to discharge flushed wastewater and impurities. After cleaning is complete, the drain valve assembly 7343 can be closed to restore the normal circulation of the cooling system.

[0054] In some feasible embodiments, the leak detection component includes a pressure sensing module, a liquid level sensing module, and an audible and visual alarm module. The pressure sensing module is installed on the delivery pipeline of each cooling water circuit to monitor the water pressure changes in the water circuit in real time. When a leak occurs in the water circuit, the water pressure in the pipeline will drop abnormally, and the pressure sensing module can immediately capture this abnormal signal. The liquid level sensing module is installed in the liquid receiving tank of easily leaking nodes such as the rotary annular connecting interface 713 and the double-layer sealing ring 715. When a leak occurs at the above nodes, the leaking cooling water will flow into the liquid receiving tank, and the liquid level sensing module can immediately detect the liquid level exceeding the standard signal.

[0055] Both the pressure sensing module and the liquid level sensing module are electrically connected to the audible and visual alarm module. When the audible and visual alarm module receives a signal of abnormal pressure or excessive liquid level, it can immediately trigger an alarm to remind staff to handle the situation promptly.

[0056] In some feasible embodiments, refer to Figure 7 As shown, the waste heat recovery module 74 includes a heat exchange storage tank 741, a tubular heat exchange component 742, and a hot water delivery pipeline 743. The tubular heat exchange component 742 is connected to both the outlet of the cooling water control module 73 and the heat exchange storage tank 741. Warm water, after heat exchange, flows out from the outlet of the cooling water control module 73 and enters the heat exchange channel of the tubular heat exchange component 742, where it undergoes non-contact heat exchange with the cold water in the heat exchange storage tank 741. This transfers the waste heat from the cooling water to the cold water in the heat exchange storage tank 741, raising the temperature of the cold water and completing waste heat recovery. The hot water delivery pipeline 743 is connected to the heat exchange storage tank 741 and is used to deliver preheated hot water to supporting equipment such as raw material preheating in injection molding equipment and heating in the production workshop, achieving secondary utilization of thermal energy and reducing overall energy consumption during production.

[0057] In some feasible embodiments, the two sets of independent cooling branches 714 of the front mold cooling module 71 are adapted to the soft rubber injection molding station and the hard rubber injection molding station, respectively. Soft rubber and hard rubber have significantly different material properties, and soft rubber requires a higher cooling rate for molding. Therefore, the water flow rate of the cooling branch corresponding to the soft rubber injection molding station is higher than that of the cooling branch corresponding to the hard rubber injection molding station, which can meet the process requirements of rapid cooling and shaping of soft rubber. Furthermore, the cooling water path of the soft rubber injection molding station is set close to the inner wall of the soft rubber molding area of ​​the milk powder can lid, maximizing its proximity to the soft rubber melt, improving heat exchange efficiency, ensuring uniform cooling of the soft rubber molding area, avoiding deformation of the sealing surface caused by uneven cooling, and improving the sealing performance of the milk powder can lid.

[0058] See Figure 9 As shown, the present invention also provides an injection molding method for producing a two-color injection mold for milk powder can lids, which can be implemented on the mold described in the above embodiments. The injection molding method includes the following steps:

[0059] S100, the gradient water circulation cooling system is started. The variable frequency booster water pump 732 of the cooling water control module 73 is started, and the cooling water at the preset temperature in the constant temperature water tank 731 is delivered to the front mold cooling module 71 and the rear mold cooling module 72. The flow rate and on / off state of the cooling water circuit of the front mold and the rear mold are adjusted by the water circuit switching valve group 733 respectively, so that the soft rubber injection station, the hard rubber injection station, and the rear mold core 21 reach the preset cooling temperature and water flow rate respectively, so as to prepare for the injection operation and ensure that stable gradient cooling can be achieved after the injection begins.

[0060] In step S200, hard and soft rubber materials are added to the barrels of the corresponding injection molding equipment via automatic feeding machines. After preheating and plasticizing, the second mold shell 2 is driven to move towards the first mold shell 1 to complete mold closing. Simultaneously, two-color injection molding is performed. Hard rubber is injected into the molding station 111 in the lower half of the front mold core 11 to form the can lid base, completing the semi-finished product injection molding of the main structure of the milk powder can lid. Soft rubber is injected into the molding station 111 in the upper half of the front mold core 11 to form a sealing layer, completing the injection molding of the soft rubber sealing layer for the semi-finished product that has already undergone hard rubber injection molding, resulting in the finished two-color milk powder can lid. During the injection molding process, a gradient water circulation cooling system continuously provides differentiated gradient cooling to the two molding stations 111 and the rear mold core 21 to adapt to the molding cooling requirements of different materials. The waste heat recovery module 74 simultaneously recovers the waste heat from the cooling water after heat exchange, achieving simultaneous cooling and waste heat recovery.

[0061] S300, after injection molding and pressure holding are completed, the second mold shell 2 is driven to move away from the first mold shell 1 to complete the mold opening action, so that the first mold shell 1 and the second mold shell 2 are separated from each other, and the front mold core 11 and the rear mold core 21 are separated simultaneously. During the mold opening process, the front mold cooling module 71 always maintains the connection between the first cooling water channel 711 and the second cooling water channel 712 through the rotary annular connecting interface 713, so as to realize the uninterrupted circulation of cooling water and avoid problems such as product temperature rise and deformation caused by cooling interruption during the mold opening process.

[0062] After the mold is opened, the second drive cylinder 51 and the third drive cylinder 53 start to operate simultaneously. The second drive cylinder 51 drives the sliding seat 52 to move to the right, and drives the front mold core 11 to be pushed out to the right through the rotating spindle 61. At the same time, the third drive cylinder 53 drives the ejector pin assembly 54 to be pushed out to the right in sync, pushing out the two-color milk powder can lid finished product and soft rubber gate formed in the upper part of the front mold core 11. Then the robot arm extends into the mold, takes out the formed two-color milk powder can lid finished product and soft rubber gate, and completes the finished product unloading and gate cleaning.

[0063] After the robotic arm completes the part removal in S500, the first drive cylinder 64 is activated, driving the meshing rack 65 to move linearly. Through the meshing transmission of the transmission gear 63 and the meshing rack 65, the sliding bushing 62, the rotating spindle 61, and the front mold core 11 rotate 180°, causing the positions of the two molding stations 111 to be interchanged. The station for the semi-finished product after hard plastic injection molding is rotated to the soft plastic injection molding position, and the empty station is rotated to the hard plastic injection molding position. During the rotation, the rotating annular connecting interface 713 of the front mold cooling module 71 rotates synchronously with the rotating spindle 61, ensuring uninterrupted cooling water circulation. Furthermore, the independent cooling branches 714 of the two stations switch cooling parameters synchronously with the position change of the molding stations 111, so that the interchanged stations immediately adapt to the cooling requirements of the corresponding injection molding materials, ensuring the continuity and adaptability of cooling.

[0064] S600, after the front mold core 11 completes the rotation and repositioning, the second drive cylinder 51 and the third drive cylinder 53 operate in opposite directions, driving the ejector pin assembly 54 and the front mold core 11 to move to the left to complete the reset. Then, the second mold shell 2 is driven to move to the first mold shell 1 to close the mold again. By repeating the operation process of steps S200-S500, continuous automated injection molding production of two-color milk powder can lids can be realized, which greatly improves production efficiency.

[0065] When the S700 equipment completes its production task and shuts down, or reaches its preset scheduled maintenance cycle, the automatic cleaning component is activated. The descaling agent metering tank 7342 adds a metered amount of descaling agent to the inlet of the high-pressure flushing pump 7341. The high-pressure flushing pump 7341 drives the cooling water mixed with the descaling agent to form a high-pressure flushing water flow within the water circuit, performing high-pressure flushing and descaling on the inner walls of the entire cooling water circuit. The flushed wastewater and impurities are discharged through the drain valve assembly 7343 at the end of each water circuit, completing the water circuit cleaning. After cleaning, a comprehensive leak detection component is simultaneously used to perform leak detection on all nodes of the water circuit, identifying potential leaks in the water circuit seals and ensuring stable operation of subsequent production.

[0066] In some feasible embodiments, during the continuous injection molding process of steps S100-S600, the pressure sensing module and liquid level sensing module of the leakage detection component monitor the water circuit operation status in real time throughout the process. If the pressure sensing module detects an abnormal drop in water circuit pressure, or the liquid level sensing module detects that the liquid level at a leak-prone node exceeds the standard, the abnormal signal is immediately transmitted to the audible and visual alarm module. The audible and visual alarm module immediately issues an audible and visual warning. At the same time, the cooling water control module 73 synchronously controls the variable frequency booster water pump 732 to stop urgently and closes the water circuit switching valve group 733 to cut off the water supply of the entire cooling water circuit, so as to avoid the leakage fault from expanding and prevent the cooling water from entering the mold cavity and causing product scrapping, or flowing into the equipment and causing electrical faults.

[0067] In some feasible embodiments, during the injection molding process in step S200, the flow rate of cooling water is gradually adjusted by the variable frequency booster water pump 732 according to the injection molding progress of the milk powder can lid, to achieve stepped cooling temperature control. In the early stage of injection molding, when the melt has just completed cavity filling, low flow rate cooling is used to avoid molding defects such as weld lines, insufficient filling, and excessive internal stress caused by rapid cooling of the melt, and to ensure that the melt is fully fused in the cavity and to hold pressure and compensate for shrinkage. In the later stage of injection molding and holding pressure, when the melt has completed cavity filling and holding pressure, high flow rate cooling is used to accelerate the cooling and solidification speed of the melt, shorten the product molding cycle, and at the same time ensure the dimensional accuracy of the product and avoid shrinkage deformation problems.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A two-color injection mold for producing milk powder can lids, characterized in that, include: A first mold shell, with a front mold core embedded inside the first mold shell; The second mold shell is slidable in the horizontal left and right direction and is located on the right side of the first mold shell. The second mold shell has a rear mold core embedded inside. After the front mold core and the rear mold core are molded together, they form a molding cavity for the two-color milk powder can lid. The front mold core has two molding stations that are centrally symmetrically distributed. Both the soft rubber hot runner assembly and the hard rubber hot runner assembly are installed inside the first mold shell, and the two are arranged vertically in space, respectively corresponding to and connected to the two molding stations of the front mold core. An ejection mechanism is located inside the first mold shell and is connected to the front mold core for synchronous ejection of the front mold core, the molded two-color milk powder can lid and the soft rubber gate. The ejection mechanism includes a second drive cylinder, a sliding seat, a third drive cylinder and an ejector pin assembly. A rotary positioning mechanism is set inside the first mold shell and fixedly connected to the front mold core. It is used to drive the front mold core to rotate and position after it is pushed out to the right, so that the spatial positions of the two forming stations are interchanged. The rotary positioning mechanism includes a rotary spindle, a sliding bushing, a transmission gear, a first drive cylinder, and a meshing rack. A gradient water circulation cooling system is installed inside the first mold shell, the front mold core, and the rear mold core. It includes a front mold cooling module, a rear mold cooling module, a cooling water control module, and a waste heat recovery module. The front mold cooling module is adapted to the front mold core, and the rear mold cooling module is adapted to the rear mold core. Both are connected to the cooling water control module. The waste heat recovery module is connected to the outlet of the cooling water control module to realize the recovery and reuse of the heat energy of the cooling water. The front mold cooling module includes a first cooling water channel, a second cooling water channel, a rotary annular connecting interface, and independent cooling branches for each workstation. The first cooling water channel is located inside the sliding seat, and the second cooling water channel is located along the axis of the rotating spindle. The two are connected by the rotary annular connecting interface. Double-layer sealing rings are provided on both sides of the rotary annular connecting interface. There are two sets of independent cooling branches for each workstation, which are adapted to the two forming workstations of the front mold core respectively. The water pipe diameter and water flow rate of the two sets of independent cooling branches can be adjusted independently. The rear mold cooling module includes a rear mold main cooling water channel, a mold cavity fitting cooling flow hole, and a heat insulation layer. The mold cavity fitting cooling flow hole is opened inside the rear mold core on the side facing the molding cavity and is connected to the rear mold main cooling water channel. The heat insulation layer is set at the mating surface between the rear mold core and the second mold shell to reduce the loss of cold energy from the rear mold cooling module.

2. The two-color injection mold for producing milk powder can lids according to claim 1, characterized in that, The cooling water control module includes a constant temperature water storage tank, a variable frequency booster pump, a water circuit switching valve group, an automatic cleaning component, and a leakage detection component. The variable frequency booster pump is connected to the constant temperature water storage tank and is used to adjust the delivery pressure and flow rate of the cooling water. The water circuit switching valve group is connected to the front mold cooling module and the rear mold cooling module respectively, and is used to realize the independent on / off and precise flow adjustment of the cooling water circuits of the front mold and the rear mold. The automatic cleaning component is used to automatically flush and descale the water circuits of the entire water circulation cooling system. The leakage detection component is set at each connection node of the water circuit and is used to detect the leakage status of the water circuit in real time and issue an early warning signal.

3. The two-color injection mold for producing milk powder can lids according to claim 2, characterized in that, The automatic cleaning assembly includes a high-pressure flushing pump, a descaling agent metering storage box, and a drain valve assembly. The high-pressure flushing pump is connected to a constant temperature water tank, the descaling agent metering storage box is connected to the water inlet of the high-pressure flushing pump, and the drain valve assembly is located at the end of each cooling water circuit to discharge the flushed wastewater and impurities.

4. The two-color injection mold for producing milk powder can lids according to claim 2, characterized in that, The leakage detection component includes a pressure sensing module, a liquid level sensing module, and an audible and visual alarm module. The pressure sensing module is installed on the delivery pipeline of each cooling water circuit, and the liquid level sensing module is installed in the liquid receiving tank of the rotary annular connecting interface and the double-layer sealing rubber ring. Both the pressure sensing module and the liquid level sensing module are electrically connected to the audible and visual alarm module.

5. The two-color injection mold for producing milk powder can lids according to claim 1, characterized in that, The waste heat recovery module includes a heat exchange storage tank, a tubular heat exchange component, and a hot water delivery pipeline. The tubular heat exchange component is connected to the outlet of the cooling water control module and the heat exchange storage tank, respectively, and is used to transfer the waste heat in the cooling water to the cold water in the heat exchange storage tank. The hot water delivery pipeline is connected to the heat exchange storage tank and is used to deliver the preheated hot water to the heating equipment of the injection molding equipment.

6. The two-color injection mold for producing milk powder can lids according to claim 1, characterized in that, The two sets of independent cooling branches of the front mold cooling module are adapted to the soft rubber injection molding station and the hard rubber injection molding station, respectively. The water flow rate of the cooling branch corresponding to the soft rubber injection molding station is higher than that of the cooling branch corresponding to the hard rubber injection molding station, and the cooling water channel of the soft rubber injection molding station is set to fit the inner side wall of the soft rubber molding area of ​​the milk powder can lid.

7. An injection molding method for a two-color injection mold used to produce milk powder can lids, which can be implemented on the mold as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S100, start the gradient water circulation cooling system, the variable frequency booster water pump of the cooling water control module starts, and delivers the cooling water in the constant temperature water tank to the front mold cooling module and the rear mold cooling module. The flow rate of the cooling water in the front mold and the rear mold is adjusted by the water circuit switching valve group so that the soft rubber injection station, the hard rubber injection station and the rear mold core reach the preset cooling temperature and water flow rate respectively. S200: Hard plastic raw material and soft plastic raw material are added to the barrel of the corresponding injection molding equipment through an automatic feeding machine. After the raw material is plasticized, the mold is closed and injection molding is performed. Hard plastic is injected at the molding station of the lower half of the front mold core to form the can lid base, and soft plastic is injected at the molding station of the upper half of the front mold core to form the sealing layer, thus obtaining the finished product of the two-color milk powder can lid. During the injection molding process, the gradient water circulation cooling system continuously performs differentiated gradient cooling, and the waste heat recovery module simultaneously recovers the waste heat of the cooling water. S300, after injection molding and pressure holding are completed, the mold is opened, so that the first mold shell and the second mold shell are separated from each other, and the front mold core and the rear mold core are separated. During the mold opening process, the front mold cooling module keeps the cooling water circulating continuously through the rotary annular connecting interface. S400, the second and third drive cylinders start synchronously to eject the front mold core, and eject the two-color milk powder can lid finished product and soft rubber gate formed in the upper part of the front mold core. The robot arm extends into the part removal area to remove the two-color milk powder can lid finished product and soft rubber gate. S500, the first drive cylinder drives the meshing rack to move, and through the gear and rack meshing transmission, it drives the front mold core to rotate 180°. During the rotation, the rotating annular connecting interface of the front mold cooling module rotates synchronously with the rotating main shaft to keep the cooling water circulation uninterrupted. The cooling parameters of the two sets of independent cooling branches of the workstation are switched synchronously as the position of the molding workstation is changed. S600, the second and third drive cylinders move in opposite directions, driving the ejector pin assembly and the front mold core to reset, closing the mold again and repeating steps S200-S500 to achieve continuous injection molding production of two-color milk powder can lids. When the S700 is shut down or undergoes regular maintenance, the automatic cleaning component is activated to add a measured amount of descaling agent to the cooling water circuit and perform high-pressure flushing using a high-pressure flushing pump. The flushed wastewater is discharged through the drain valve group, and at the same time, the leak detection component detects leaks at each node of the water circuit.

8. The injection molding method for producing a two-color injection mold for milk powder can lids according to claim 7, characterized in that, In steps S100-S600, the leakage detection component monitors the water circuit operation status in real time throughout the process. If abnormal water circuit pressure or excessive liquid level in the receiving tank is detected, the audible and visual alarm module immediately issues an audible and visual warning. At the same time, the cooling water control module controls the variable frequency booster pump to stop and closes the water circuit switching valve group.

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