Conformal cooling injection mold and cooling process for deep cavity parts
Patent Information
- Application Number
- CN202611290783.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-25
- Publication Date
- 2026-10-13
AI Technical Summary
[0007]本发明的目的在于提供深腔件的随形冷却注塑模具及冷却工艺，以解决方柱形深腔型芯的四个纵向直角棱边存在散热死角且常规折线水路导致流阻过大、易产生死水区的问题
[0038]本发明的水道拓扑布局利用前端螺旋流道的低阻力平滑过渡特性保障了系统的全局循环流速，同时利用尾端四路分流直达棱边的路径设计弥补了常规圆形螺旋无法覆盖方形死角的结构缺陷，从而在不增加模具系统总体水头损失的前提下，从物理路径上消除了方柱型深腔型芯的散热死角，实现了深腔件的低流阻均温冷却。
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Figure CN122896366A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of conformal cooling molds, and more specifically to conformal cooling injection molds and cooling processes for deep cavity parts. Background Technology
[0002] In the injection molding process of complex deep-cavity parts (especially columnar deep-cavity parts with square or rectangular cross-sections), the heat distribution of the mold is extremely uneven. Due to the high concentration of heat inside the molding cavity and the extremely limited internal heat dissipation space, the deep cavity core on the moving mold side often becomes the most fatal cooling bottleneck of the entire mold. It is very easy for insufficient cooling or excessive local temperature difference to cause shrinkage, internal stress concentration or warping deformation of the molded part.
[0003] To improve the cooling efficiency of the core, existing injection molds typically utilize additive manufacturing technology to machine conformal cooling channels that fit the product's contours inside the moving mold core. However, the design of cooling channels for deep-cavity rectangular cores has long faced a technical challenge of reconciling fluid mechanics and thermodynamics.
[0004] Conventional conformal water channels often employ a three-dimensional spiral structure with a circular top-view projection. When applied to a square core, the circular water channel trajectory cannot effectively cover the four longitudinal right-angled edges of the core's perimeter, resulting in severe heat dissipation dead zones in these four edge areas.
[0005] To eliminate these dead zones, some conventional designs attempt to make each turn of the spiral water channel a square spiral or rounded rectangle that matches the outer contour of the core. However, for deep-cavity cores, the water channel usually needs to coil several times along the axial direction. This geometry means that the coolant needs to undergo several times the number of sharp turns in a single cycle.
[0006] Frequent sharp turns not only cause significant local head loss and pressure drop in the coolant, placing stringent demands on the pumping head of the external refrigerant system, but also easily induce fluid boundary layer separation and stagnant water eddies on the inner side of the flow channel corners. The presence of stagnant water zones not only blocks local heat conduction but also causes a sharp drop in the overall flow velocity of the pipeline, severely weakening the overall convective heat transfer efficiency of the core. Summary of the Invention
[0007] The purpose of this invention is to provide a conformal cooling injection mold and cooling process for deep cavity parts, so as to solve the problems of heat dissipation dead corners on the four longitudinal right-angle edges of the square column deep cavity core and the excessive flow resistance and the easy generation of dead water zones caused by conventional zigzag water channels.
[0008] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:
[0009] The conformal cooling injection mold for deep cavity parts includes a fixed mold and a moving mold that cooperates with the fixed mold. A square column-shaped core is formed on the moving mold. After the fixed mold and the moving mold are closed, the core and the cavity of the fixed mold together form the injection molding cavity of the deep cavity part. The core is provided with conformal cooling channels, which include three-dimensional spiral channels, planar spiral channels, central axial flow channels and four branch return channels.
[0010] The core has a deep cavity forming end near the bottom of the forming cavity and an mounting bottom end away from the forming cavity;
[0011] The three-dimensional spiral water channel extends spirally around the axis of the core. Its water inlet is located at the bottom of the installation and is connected to the external refrigerant circulation system. Its water outlet extends to the deep cavity forming end and is directly connected to the inlet of the planar spiral water channel.
[0012] A planar spiral waterway is coiled and distributed inside the end face of the deep cavity forming end, and its outlet is located in the central area of the end face;
[0013] One end of the central axial flow channel is connected to the outlet of the planar spiral water channel, and the other end extends a set distance along the axial direction of the core toward the mounting bottom, then splits into four branch return channels.
[0014] The four branch return channels extend radially to the four longitudinal edges of the core, and after being bent, they extend axially along the edges to the bottom of the installation. The four branch return channels extend and connect to the return water end of the external refrigerant circulation system at the bottom of the installation.
[0015] Furthermore, a Venturi structure is formed on the pipe section through the longitudinal edge region of the core in each branch return channel to locally accelerate the coolant flowing through the region and disrupt the fluid thermal boundary layer there.
[0016] Furthermore, the Venturi structure includes a contraction section, a throat, and an expansion section that are smoothly connected in sequence along the direction of fluid flow, with the flow cross-sectional area of the throat being smaller than the basic flow cross-sectional area of the branch return channel.
[0017] A turbulence column is formed inside the throat, spanning the cross-section of the throat, and the turbulence column divides the fluid channel of the throat into two.
[0018] The cross-section of the turbulence column is teardrop-shaped, with the blunt end of the teardrop facing the contraction section and the sharp end facing the expansion section.
[0019] Furthermore, a fluid buffer chamber is provided at the junction of the central axial flow channel and the four branch return channels;
[0020] The flow cross-sectional area of the fluid buffer chamber is larger than that of the central axial flow channel, so as to convert the dynamic pressure of the coolant from the central axial flow channel into static pressure, and distribute the coolant equally to the four branch return channels with uniform static pressure.
[0021] Furthermore, the four branch return channels converge at the bottom of the installation and are connected in series with the return water end of the external refrigerant circulation system through a throttling device.
[0022] Furthermore, the geometric parameters of the Venturi structure satisfy:
[0023] The ratio of the net flow cross-sectional area of the throat after removing the space occupied by the turbulence column to the basic flow cross-sectional area of the branch return channel is 40% to 70%.
[0024] The tapering cone angle of the contraction section is 15° to 25°;
[0025] The gradually expanding cone angle of the expansion section is 5° to 15°, and the central axial length of the expansion section is greater than that of the central axial length of the contraction section.
[0026] Furthermore, the core adopts a heterogeneous composite metal forming structure, which includes an inner core, a thermally conductive interface layer, and a mold steel surface layer from the inside out.
[0027] The inner core is made of copper alloy, and a three-dimensional spiral waterway and a central axial flow channel are formed inside the inner core.
[0028] The mold steel surface completely covers the outer contour surface of the inner core, allowing it to directly contact the injection molten metal and bear pressure.
[0029] The thermally conductive interface layer is located between the inner core and the mold steel surface layer. The thermally conductive interface layer is a metal-based gradient transition layer containing graphene nanomaterials. The inner core, the thermally conductive interface layer and the mold steel surface layer are formed by additive manufacturing.
[0030] The conformal cooling process for deep cavity components includes the following steps:
[0031] S1, during the process of mold closing and melt filling of the fixed mold and moving mold, the external refrigerant circulation system is controlled to pump coolant into the core at the basic flow rate, so that the three-dimensional spiral channel, the planar spiral channel, the central axial flow channel and the four branch return channels are always filled with coolant and maintain low-speed circulation, thereby establishing the initial liquid static pressure in the conformal cooling channel without affecting the melt filling fluidity.
[0032] S2, after the melt filling and pressure holding is completed, the pumping power of the external refrigerant circulation system is increased, and the coolant rotates at high speed along the three-dimensional spiral water channel and the planar spiral water channel in sequence to carry out large-area heat exchange on the outer periphery and bottom end face of the molding cavity.
[0033] Subsequently, the high-speed coolant isobarically split into four high-speed coolant streams, which are injected into four branch return channels respectively. When flowing through the Venturi structure, the local flow velocity surges and impacts the turbulence column to induce wake fluid disturbance, thereby forcibly cooling the thermal boundary layer at the longitudinal right-angle edge.
[0034] S3, during the forced cooling process in step S2, the mold temperature control system monitors the liquid supply pressure P at the initial inlet in real time. in And adjust the set back pressure P of the throttling device. throttle , making P min <P throttle <P in -ΔP drop ;
[0035] Among them, the upper limit P in -ΔP drop To maintain the flow conditions necessary for the coolant to overcome the total resistance of the entire system flow path and maintain positive circulation, ΔP drop The lower limit P is the total pressure drop of the coolant flowing through the entire flow channel inside the core. min The preset anti-cavitation static pressure threshold is used to raise the base static pressure of the entire flow channel, so as to achieve the minimum local static pressure P when the coolant flows through the throat of the Venturi structure. throat Always maintain a pressure greater than the saturated vapor pressure P of the coolant sat Within the safe zone, P sat This is the saturated vapor pressure of the coolant at the current mold cavity molding temperature.
[0036] S4. After cooling and solidification, reduce the pumping power of the external refrigerant circulation system to the basic flow rate, open the mold to eject the deep cavity part, and repeat step S1.
[0037] The beneficial effects of this invention are:
[0038] The water channel topology layout of this invention utilizes the low-resistance smooth transition characteristics of the front spiral flow channel to ensure the global circulation velocity of the system. At the same time, the four-way branching path design at the tail end directly reaches the edge to make up for the structural defect that conventional circular spirals cannot cover square dead corners. Thus, without increasing the overall head loss of the mold system, the heat dissipation dead corner of the square column deep cavity core is eliminated from the physical path, and low flow resistance uniform temperature cooling of the deep cavity part is achieved. Attached Figure Description
[0039] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.
[0040] Figure 1 This is a top view of the core according to an embodiment of the present invention;
[0041] Figure 2 for Figure 1 An internal perspective view of the core.
[0042] Figure 3 This is the three-dimensional shape of the conformal cooling water channel inside the core in an embodiment of the present invention.
[0043] Figure 4 for Figure 3 Bottom view of the three-dimensional shape of the conformal cooling water channel;
[0044] Figure 5 for Figure 1 Plan view of line AA;
[0045] The labels in the figure represent the following: 1-core; 1a-deep cavity forming end; 1b-installation bottom end; 2-three-dimensional spiral channel; 3-planar spiral channel; 4-central axial flow channel; 5-branch return channel; 5a-contraction section; 5b-throat; 5b1-turbulence column; 5c-expansion section; 6-fluid buffer cavity. Detailed Implementation
[0046] 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.
[0047] This embodiment provides a conformal cooling injection mold for deep cavity parts, aiming to solve the problems of heat dissipation dead angles on the four longitudinal right-angled edges of the rectangular columnar deep cavity core 1 and the excessive flow resistance and stagnant water zones caused by conventional zigzag water channels. Specifically, the conformal cooling injection mold for deep cavity parts includes a fixed mold and a moving mold that cooperates with the fixed mold. A rectangular columnar core 1 is formed on the moving mold. After the fixed mold and the moving mold are closed, the core 1 and the cavity of the fixed mold together form the injection molding cavity of the deep cavity part.
[0048] Reference Figures 1 to 5 The core 1 has a conformal cooling channel inside, which includes a three-dimensional spiral channel 2, a planar spiral channel 3, a central axial flow channel 4, and four branch return channels 5. The core 1 has a deep cavity forming end 1a near the bottom of the forming cavity and an mounting bottom end 1b away from the forming cavity.
[0049] The three-dimensional spiral water channel 2 extends spirally around the axis of the core 1. Its inlet end is located at the mounting bottom end 1b and is connected to the external refrigerant circulation system. Its outlet end extends to the deep cavity forming end 1a and directly connects to the inlet of the planar spiral water channel 3. The planar spiral water channel 3 is coiled and distributed inside the end face of the deep cavity forming end 1a, and its outlet is located in the central area of the end face. One end of the central axial flow channel 4 is connected to the outlet of the planar spiral water channel 3, and the other end extends a set distance along the axis of the core 1 toward the mounting bottom end 1b, and then splits into four branch return channels 5.
[0050] The four branch return channels 5 extend radially to the four longitudinal edges of the core 1, and after being bent, extend axially along the edges to the mounting bottom 1b. The four branch return channels 5 extend and connect to the return water end of the external refrigerant circulation system at the mounting bottom 1b.
[0051] This embodiment constructs a basic heat exchange front section composed of three-dimensional and planar spiral water channels 3 and a directional reflux rear section composed of four branch reflux channels 5 by topologically decoupling the conformal cooling water channels inside the core 1.
[0052] In the cooling cycle, the coolant first smoothly swirls along the three-dimensional spiral water channel 2 and the planar spiral water channel 3 to perform basic heat exchange on the outer peripheral wall and bottom end face of the core 1, avoiding the local dead water eddies and high fluid pressure drop caused by the water channel continuously bending at right angles along the outer contour of the square column.
[0053] After the basic heat exchange, the fluid then converges through the central axial flow channel 4 and is directly diverted to the branch return channels 5 located at the four longitudinal edges of the core 1, achieving directional cooling of the heat accumulation area of the right-angle edges through independent edge-attached pipes.
[0054] Although the above topology achieves fluid coverage of the entire tube wall and end face of the core 1, if the core 1 is made of a single mold steel material, its relatively low thermal conductivity will limit the heat exchange potential of the water channel; if pure copper material is used, the mechanical strength cannot withstand the high pressure of the injection molding stage.
[0055] To resolve the material conflict between thermal conductivity and mechanical strength in core 1, core 1 employs a heterogeneous composite metal molding structure, comprising, from the inside out, an inner core, a thermally conductive interface layer, and a mold steel surface layer. The inner core is made of copper alloy, with a three-dimensional spiral channel 2 and a central axial flow channel 4 formed within it. The mold steel surface layer completely covers the outer contour surface of the inner core, allowing it to directly contact the injection molten metal and bear pressure. The thermally conductive interface layer is located between the inner core and the mold steel surface layer. This layer is a metal-based gradient transition layer containing graphene nanomaterials, and the inner core, thermally conductive interface layer, and mold steel surface layer are formed through additive manufacturing.
[0056] In the water channel layout inside the core 1, four branch return channels 5 are directed to four longitudinal edges. However, under normal constant-diameter pipe flow conditions, the fluid velocity near the pipe wall is extremely low, easily forming a fluid thermal boundary layer that hinders heat transfer, making it difficult to quickly remove localized heat accumulation at right angles. To break this local thermal barrier, a Venturi structure is formed on the pipe section of each branch return channel 5 passing through the longitudinal edge region of the core 1, which is used to locally accelerate the coolant flowing through this region to disrupt the fluid thermal boundary layer.
[0057] A single Venturi structure can only accelerate the fluid; the fluid particles may still maintain a steady flow, limiting its ability to penetrate and transfer heat to stubborn heat buildup in deep, dead zones. To further convert the increased fluid kinetic energy into intense local turbulence, the Venturi structure includes a contraction section 5a, a throat 5b, and an expansion section 5c that are smoothly connected sequentially along the fluid flow direction. The flow cross-sectional area of the throat 5b is smaller than the basic flow cross-sectional area of the branch return channel 5. A turbulence column 5b1 is formed within the throat 5b, spanning its cross-section and dividing the fluid channel in the throat 5b into two. To reduce the mechanical pressure drop caused by the added obstruction to the piping system, the cross-section of the turbulence column 5b1 is teardrop-shaped, with the blunt end of the teardrop facing the contraction section 5a and its sharp end facing the expansion section 5c.
[0058] To clarify the specific dimensional boundaries and physical effects of the Venturi structure, and to overcome resistance overload or flow separation caused by improper size selection, the geometric parameters of the Venturi structure must satisfy:
[0059] The net flow cross-sectional area of the throat 5b after removing the space occupied by the turbulence column 5b1 is 40% to 70% of the basic flow cross-sectional area of the branch return channel 5; the tapering cone angle of the contraction section 5a is 15° to 25°; the tapering cone angle of the expansion section 5c is 5° to 15°, and the central axial length of the expansion section 5c is greater than the central axial length of the contraction section 5a.
[0060] The ratio of the net flow cross-sectional area of the throat 5b after removing the space occupied by the turbulence column 5b1 to the basic flow cross-sectional area of the branch return channel 5 determines the velocity increment and static pressure drop of the coolant when passing through the throat 5b. If this ratio is greater than 70%, the cross-sectional contraction is small, the increase in coolant velocity is limited, and it is difficult to form a vortex behind the turbulence column 5b1 sufficient to destroy the fluid thermal boundary layer, thus weakening the local convective heat transfer effect.
[0061] If this ratio is less than 40%, excessive cross-sectional contraction and a sharp increase in flow velocity will lead to low local static pressure at the throat (5b), increasing the probability of cavitation cavitation. Simultaneously, the increased resistance generated by fluid flowing through the narrow cross-section will cause an overall increase in the pressure drop of the pipeline system, increasing the pumping load on external liquid supply equipment. Limiting this ratio to the range of 40% to 70% can trigger turbulent heat transfer while keeping the pressure drop of the pipeline system within a reasonable threshold.
[0062] The tapered angle of the contraction section 5a is 15°–25°. Within this region, the fluid flow is accelerated by the pressure gradient. If the tapered angle is greater than 25°, the pipe wall contracts more rapidly, and local eddies and fluid impacts are easily generated at the inlet edge of the contraction section 5a, resulting in mechanical energy dissipation. If the tapered angle is less than 15°, the axial length required to achieve the target contraction ratio will increase. Under the condition of limited internal space in the core 1, a longer contraction section 5a will encroach on the space used to arrange the throat 5b and the expansion section 5c. Limiting the tapered angle to 15°–25° can balance the smoothness of the fluid acceleration process and the utilization rate of the internal space of the mold.
[0063] The expansion section 5c is located in the reverse pressure gradient region, where the flow velocity decreases and the static pressure increases. If the diverging cone angle is greater than 15°, boundary layer stripping is likely to occur at the expansion pipe wall, leading to the formation of vortex regions on both sides of the pipe wall. This reduces the surface heat transfer coefficient of the expansion section 5c region, and the fluid kinetic energy is dissipated in vortex friction, hindering the recovery of static pressure energy. By limiting the diverging cone angle to 5°–15° and setting the central axial length of the expansion section 5c to be greater than that of the contraction section 5a, a gentle velocity reduction space is provided for the fluid. The coolant smoothly recovers static pressure over a longer diffusion path, reducing the energy loss along the path during dynamic pressure recovery, mitigating the increased system flow resistance caused by the addition of the Venturi structure, and maintaining the circulating flow velocity within the branch return channel 5.
[0064] When the coolant flows outward from the central axial flow channel 4 to the four branch return channels 5, the fluid carries a high axial dynamic pressure. Direct structural flow diversion will cause uneven fluid distribution and dynamic pressure pulsation, resulting in differences in flow velocity within the four branch return channels 5.
[0065] To eliminate dynamic pressure interference at the branching nodes and achieve uniform distribution, a fluid buffer chamber 6 is provided at the junction of the central axial flow channel 4 and the four branch return channels 5. The flow cross-sectional area of the fluid buffer chamber 6 is larger than that of the central axial flow channel 4, so as to convert the dynamic pressure of the coolant from the central axial flow channel 4 into static pressure, and distribute the coolant equally to the four branch return channels 5 with uniform static pressure.
[0066] When the coolant is locally and extremely accelerated as it flows through the throat 5b of the Venturi structure, the local static pressure of the fluid will drop sharply according to Bernoulli's equation. Once this local static pressure falls below the saturated vapor pressure of the liquid at ambient temperature, destructive cavitation will occur. To physically block cavitation conditions at the system level, the four branch return channels 5 converge after the installation end 1b and are connected in series with the return end of the external refrigerant circulation system through a throttling device (generally a throttling valve or a back pressure valve, which is not limited in this embodiment).
[0067] This embodiment also provides a conformal cooling process for deep cavity parts, used to achieve thermodynamic control that matches the molding sequence based on the above-mentioned mold hardware architecture. Conventional constant flow cooling cannot simultaneously meet the heat preservation requirements of the melt filling stage and the high-frequency quenching requirements of the solidification stage.
[0068] To this end, the process involves the coordinated adjustment of pump flow rate and tail-end back pressure, including the following steps:
[0069] S1, during the process of mold closing and melt filling of the fixed mold and moving mold, the external refrigerant circulation system is controlled to pump coolant into the core 1 at the basic flow rate, so that the three-dimensional spiral channel 2, the planar spiral channel 3, the central axial flow channel 4 and the four branch return channels 5 are always filled with coolant and maintain low-speed circulation, thereby establishing the initial liquid static pressure in the conformal cooling channel without affecting the melt filling fluidity;
[0070] S2, after the melt filling and pressure holding is completed, the pumping power of the external refrigerant circulation system is increased, and the coolant rotates at high speed along the three-dimensional spiral water channel 2 and the planar spiral water channel 3 in sequence to perform large-area heat exchange on the outer periphery and bottom end face of the molding cavity.
[0071] Subsequently, the high-speed coolant isobarically split into four high-speed coolant streams and injected into four branch return channels 5 respectively. When flowing through the Venturi structure, the local flow velocity surges and impacts the turbulence column 5b1 to induce wake fluid disturbance, so as to force the thermal boundary layer at the longitudinal right-angle edge to be cooled.
[0072] S3, during the forced cooling process in step S2, the mold temperature control system monitors the liquid supply pressure P at the initial inlet in real time. in And adjust the set back pressure P of the throttling device. throttle , making P min <P throttle <P in -ΔP drop .
[0073] Among them, the upper limit P in -ΔP drop To maintain the flow conditions necessary for the coolant to overcome the total resistance of the entire system flow path and maintain positive circulation, ΔP dropThe lower limit P is the total pressure drop of the coolant flowing through the entire internal flow channel of core 1. min The preset anti-cavitation static pressure threshold is used to raise the base static pressure of the entire flow channel, so as to achieve the minimum local static pressure P when the coolant flows through the throat 5b of the Venturi structure. throat Always maintain a pressure greater than the saturated vapor pressure P of the coolant sat Within the safe zone, P sat This is the saturated vapor pressure of the coolant at the current molding temperature of the mold cavity.
[0074] S4. After cooling and solidification, reduce the pumping power of the external refrigerant circulation system to the basic flow rate, open the mold to eject the deep cavity part, and repeat step S1.
[0075] In the dynamic pressure control stage of step S3, the total pressure drop ΔP of the coolant flowing through the entire flow channel inside the core 1 is... drop It is a physical parameter that dynamically changes with fluid velocity, fluid viscosity, and the geometric resistance inside the flow channel. To ensure that the mold temperature control system can accurately execute P... min <P throttle <P in -ΔP drop Traffic flow conditions, ΔP drop The methods for obtaining the data include hardware testing or software lookup table methods, and the system can choose to use one of these methods or cross-validate them.
[0076] In the pre-calibration based on CFD fluid simulation and PLC lookup table method, before the injection mold is put into mass production, the three-dimensional geometric model of the conformal cooling channel of core 1 is imported into the CFD computational fluid dynamics software. Combined with the physical properties of the coolant, the theoretical pressure drop constant ΔP generated by frictional friction and Venturi local resistance in the entire flow channel under the high-power high-frequency quench flow rate calibrated in stage S2 is calculated. drop_theory .
[0077] The theoretical pressure drop constant or flow rate-pressure drop curve is programmed into the PLC memory of the mold temperature control system. During the actual execution of step S3, the system directly reads the preset parameters as ΔP. drop It participates in the background inequality logic operations. This method eliminates the need for the hardware requirement of installing an additional pressure sensor at the tail end of the mold.
[0078] In the real-time measurement algorithm based on dual-end pressure sensors, a first pressure sensor and a second pressure sensor are configured on the external pipeline of the conformal cooling injection mold. The first pressure sensor is located at the initial inlet and is used to collect the liquid supply pressure P in real time. in The second pressure sensor is installed on the main outlet pipeline and located upstream of the throttling device to collect the residual pressure P at the end before entering the throttling device in real time. out .
[0079] The processing unit of the mold temperature control system directly obtains the actual pressure drop under the current operating conditions, i.e., ΔP, through real-time differential calculation. drop =P in -P out At this time, the system controls the opening of the throttling device to set its back pressure P. throttle Less than the measured P out This ensures smooth fluid flow. This method eliminates errors caused by changes in flow resistance due to unknown environmental factors such as scale buildup in pipes.
[0080] In the dynamic pressure control stage of step S3, because the throat 5b of the Venturi structure is deeply embedded inside the core 1 and has a very small flow cross-section, it is difficult to directly measure the local minimum static pressure P at that location using conventional physical sensors. throat To ensure the feasibility and accuracy of the anti-cavitation control logic, the mold temperature control system uses any of the following methods or cross-validation methods to obtain P. throat Real-time values:
[0081] A pre-defined lookup table method based on CFD simulation: Before mass production of the mold, the three-dimensional geometric model of the conformal cooling channel is imported into computational fluid dynamics (CFD) software. For multiple operating conditions of the external refrigerant circulation system under different pump flow rates and supply pressures, the static pressure drop amplitude of the coolant flowing through the Venturi throat 5b is pre-simulated and calculated, and the theoretical minimum static pressure value is extracted. This mapping function relationship between the "inlet parameter and throat static pressure" is used as calibration data and burned into the programmable logic controller (PLC) of the mold temperature control system.
[0082] During actual operation, the system only needs to read the real-time liquid supply pressure P at the inlet. in By looking up the total flow rate in the internal table, the P value under the current operating condition can be directly mapped. throat This avoids the hardware implementation difficulties of embedding sensors inside a narrow core.
[0083] Real-time derivation method based on fluid dynamics equations: The mold temperature control system has a built-in calculation unit that collects flow data from the external liquid supply pipeline in real time. Combining the known cross-sectional area of the basic flow path 5 of the branch return channel and the net cross-sectional area of the throat 5b, the initial flow velocity v1 of the coolant in the basic pipe section and the accelerating flow velocity v2 at the throat 5b are derived using the fluid continuity equation. Subsequently, combining the coolant density ρ and the currently measured static pressure P1 of the basic pipeline, the calculation unit calculates based on the ideal Bernoulli equation. Perform high-frequency real-time calculations.
[0084] To compensate for the discrepancy between the ideal equation and the actual flow resistance, the mold temperature control system executes P... throat >P satWhen determining the logic, a fixed safety margin constant is preset, and a conservative estimate of the local minimum static pressure and dynamic back pressure control for cavitation prevention are realized in the form of a pure algorithm.
[0085] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.
Claims
1. A conformal cooling injection mold for a deep cavity part, comprising a fixed mold and a movable mold that cooperates with the fixed mold, wherein a square columnar core (1) is formed on the movable mold, and after the fixed mold and the movable mold are closed, the core (1) and the cavity of the fixed mold together constitute the injection molding cavity of the deep cavity part, characterized in that, The core (1) is provided with conformal cooling channels inside, which include a three-dimensional spiral channel (2), a planar spiral channel (3), a central axial flow channel (4), and four branch return channels (5). The core (1) has a deep cavity molding end (1a) near the bottom of the molding cavity and a mounting bottom end (1b) away from the molding cavity. The three-dimensional spiral water channel (2) extends spirally around the axis of the core (1), with its inlet end located at the mounting bottom end (1b) and connected to the external refrigerant circulation system, and its outlet end extending to the deep cavity forming end (1a) and directly connected to the inlet of the planar spiral water channel (3). The planar spiral waterway (3) is coiled and distributed inside the end face of the deep cavity forming end (1a), and its outlet is located in the central region of the end face; One end of the central axial flow channel (4) is connected to the outlet of the planar spiral water channel (3), and the other end extends a set distance along the axial direction of the core (1) toward the mounting bottom end (1b) and then splits into four branch return channels (5). The four branch return channels (5) extend radially to the four longitudinal edges of the core (1), and after being bent, extend axially along the edges to the mounting bottom end (1b). The four branch return channels (5) extend and connect to the return water end of the external refrigerant circulation system at the mounting bottom end (1b).
2. The conformal cooling injection mold for deep cavity parts according to claim 1, characterized in that, A Venturi structure is formed on each of the branch return channels (5) passing through the longitudinal edge region of the core (1) to locally accelerate the coolant flowing through the region in order to break the fluid thermal boundary layer therein.
3. The conformal cooling injection mold for deep cavity parts according to claim 2, characterized in that, The Venturi structure includes a contraction section (5a), a throat (5b), and an expansion section (5c) that are smoothly connected in sequence along the fluid flow direction. The flow cross-sectional area of the throat (5b) is smaller than the basic flow cross-sectional area of the branch return channel (5). A turbulence column (5b1) is formed within the throat (5b) and spans the cross section of the throat (5b), the turbulence column (5b1) dividing the fluid channel of the throat (5b) into two. The cross-section of the turbulence column (5b1) is teardrop-shaped, with the blunt end of the teardrop facing the contraction section (5a) and the sharp end facing the expansion section (5c).
4. The conformal cooling injection mold for deep cavity parts according to claim 1, characterized in that, A fluid buffer chamber (6) is provided at the junction of the central axial flow channel (4) and the four branch return channels (5). The flow cross-sectional area of the fluid buffer chamber (6) is larger than that of the central axial flow channel (4) to convert the dynamic pressure of the coolant from the central axial flow channel (4) into static pressure, and to distribute the coolant equally to the four branch return channels (5) with uniform static pressure.
5. The conformal cooling injection mold for a deep cavity part according to any one of claims 1 to 4, characterized in that, The four branch return channels (5) converge after the mounting bottom (1b) and are connected in series with the return water end of the external refrigerant circulation system through a throttling device.
6. The conformal cooling injection mold for deep cavity parts according to claim 3, characterized in that, The geometric parameters of the Venturi structure satisfy: The ratio of the net flow cross-sectional area of the throat (5b) after removing the space occupied by the turbulence column (5b1) to the basic flow cross-sectional area of the branch return channel (5) is 40% to 70%. The tapered cone angle of the contraction section (5a) is 15° to 25°; The expanding section (5c) has a gradually expanding cone angle of 5° to 15°, and the central axial length of the expanding section (5c) is greater than the central axial length of the contracting section (5a).
7. The conformal cooling injection mold for deep cavity parts according to claim 1, characterized in that, The core (1) adopts a heterogeneous composite metal forming structure, which includes an inner core, a thermally conductive interface layer and a mold steel surface layer from the inside to the outside. The inner core is made of copper alloy, and the three-dimensional spiral water channel (2) and the central axial flow channel (4) are formed inside the inner core. The mold steel surface completely covers the outer contour surface of the inner core, and is used to directly contact the injection molten metal to bear pressure. The thermally conductive interface layer is located between the inner core and the mold steel surface layer. The thermally conductive interface layer is a metal-based gradient transition layer containing graphene nanomaterials. The inner core, the thermally conductive interface layer and the mold steel surface layer are formed by additive manufacturing.
8. A conformal cooling process for deep cavity parts, employing the conformal cooling injection mold for deep cavity parts as described in claim 5, characterized in that, The process includes the following steps: S1, during the process of closing the fixed mold and the moving mold and filling the melt, the external refrigerant circulation system is controlled to pump coolant into the core (1) at a basic flow rate, so that the three-dimensional spiral channel (2), the planar spiral channel (3), the central axial flow channel (4) and the four branch return channels (5) are always filled with coolant and maintain low-speed circulation, thereby establishing an initial liquid static pressure in the conformal cooling channel without affecting the melt filling fluidity; S2, after the melt filling and pressure holding is completed, the pumping power of the external refrigerant circulation system is increased, and the coolant rotates at high speed along the three-dimensional spiral water channel (2) and the planar spiral water channel (3) to perform large-area heat exchange on the outer periphery and bottom end face of the forming cavity; Subsequently, the high-speed coolant isobarically split into four high-speed coolant streams and injected into the four branch return channels (5) respectively. When flowing through the Venturi structure, the local flow velocity surges and impacts the turbulence column (5b1) to induce wake fluid disturbance, so as to force the thermal boundary layer at the longitudinal right-angle edge to be cooled. S3, during the forced cooling process in step S2, the mold temperature control system monitors the liquid supply pressure P at the initial inlet in real time. in And adjust the set back pressure P of the throttling device. throttle , making P min <P throttle <P in -ΔP drop ; Among them, the upper limit P in -ΔP drop To maintain the flow conditions necessary for the coolant to overcome the total resistance of the entire system flow path and maintain positive circulation, ΔP drop The lower limit P is the total pressure drop of the coolant flowing through the entire flow channel inside the core (1). min The preset anti-cavitation static pressure threshold for the system is used to raise the base static pressure of the entire flow channel, so as to achieve the minimum local static pressure P when the coolant flows through the throat (5b) of the Venturi structure. throat Always maintain a pressure greater than the saturated vapor pressure P of the coolant sat Within the safe zone, P sat This is the saturated vapor pressure of the coolant at the current mold cavity molding temperature. S4, after cooling and solidification, reduce the pumping power of the external refrigerant circulation system to the base flow rate, open the mold to eject the deep cavity part, and repeat step S1.