A mold suitable for small injection molded parts

Abstract

The application provides a mold suitable for small injection molded parts, comprising a movable mold, a fixed mold and a power device, a cavity is formed between the fixed mold and the movable mold, and a cooling runner with a sealed space is arranged on the fixed mold; the power device is drivingly connected with a pressure regulating assembly, the pressure regulating assembly comprises a negative pressure cavity and a positive pressure cavity, the negative pressure cavity is communicated with the cooling runner; a first cooling port towards the edge of the cavity and a second cooling port towards the length direction of the cooling runner are arranged in the cooling runner, and the first cooling port and the second cooling port can both inject liquid cooling medium into the cooling runner. In the first cooling condition, the liquid cooling medium is directionally and fixedly injected to the gap area prone to overflow at the edge of the mold cavity through the first cooling port; the liquid medium induces flash phase change when contacting the local high-temperature mold wall, and a local cooling gradient field is constructed at the edge of the cavity by the high-efficiency transfer effect of latent heat of vaporization.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, specifically to a mold suitable for small injection molded parts. Background Technology

[0002] Plastic injection molding is a core technology for achieving precision processing of polymer materials in modern manufacturing. A high-standard injection mold typically relies on the precise coordination of multiple key subsystems such as gating, molding, demolding, and temperature control. In particular, it uses cooling channels inside the cavity to dynamically conduct heat, ensuring that the molten resin can quickly solidify and be easily demolded.

[0003] However, existing mold structures often reveal significant limitations when molding specific thermoplastic materials such as polyamide (PA), polypropylene (PP), or polyethylene (PE). These resin materials exhibit extremely low viscosity and extremely high fluidity in their high-temperature molten state, causing the melt to easily flow along the mold parting surface, insert seams, or ejector pin gaps during the high-pressure injection stage. This results in unavoidable flash and burrs solidifying at the edges of the product.

[0004] To eliminate the aforementioned overflow defects, manufacturers are often forced to introduce cumbersome secondary finishing processes after molding. Traditional mechanical grinding or manual cutting not only significantly lengthens the production cycle and increases labor costs, but also carries a high risk of damaging the overall appearance of the product. Taking large automotive interior parts injection molded from PP material as an example, the overflow burrs often exhibit thin and semi-transparent film-like physical characteristics. When forcibly peeled or scraped off manually, uneven force may damage the product substrate, causing irreversible surface defects. In the field of micro-injection molded parts, where surface finish and dimensional accuracy requirements are even more stringent, these microscopic scratches caused by the post-deburring process are magnified, leading to an increased defect rate. Summary of the Invention

[0005] To address the problem of flash easily generated during injection molding of high-flow-rate materials in existing technologies, this invention provides a mold suitable for small injection molded parts, which achieves rapid cooling of the cavity edge, thereby reducing flash generation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A mold suitable for small injection molded parts includes a moving mold, a fixed mold and a power unit, wherein a cavity is formed between the fixed mold and the moving mold, and the fixed mold is provided with a cooling channel with a sealed space; The power unit is connected to a pressure regulating component, which includes a negative pressure chamber and a positive pressure chamber, with the negative pressure chamber connected to the cooling channel. The cooling channel is provided with a first cooling port facing the edge of the cavity and a second cooling port facing the length direction of the cooling channel. Both the first cooling port and the second cooling port can inject liquid cooling medium into the cooling channel. The fixed mold is also provided with a gas flow channel, which is connected to the positive pressure chamber. A first control valve is provided between the gas flow channel and the positive pressure chamber. A vacuum generating chamber is also provided in the gas flow channel. The vacuum generating chamber includes an inlet end and an outlet end. The inlet end is connected to the cooling flow channel, and the outlet end is connected to the gas flow channel.

[0007] Preferably, when the first control valve is opened, the gas in the positive pressure chamber enters the gas flow channel, and the pressure at the inlet end of the vacuum generating chamber is higher than that at the outlet end, forming a negative pressure suction effect. The gas generated by the phase change in the cooling flow channel enters from the inlet end of the vacuum generating chamber and enters the gas flow channel from the outlet end.

[0008] Preferably, the end of the gas flow channel is also connected to the second cooling port; and a bubble generating chamber is provided between the gas flow channel and the second cooling port, so that micro-nano bubbles are formed in the cooling flow channel after the gas enters the bubble generating chamber from the gas flow channel.

[0009] Preferably, the cooling channel is configured to switch between a first cooling condition, a second cooling condition, and a third cooling condition. When in the first cooling condition, the first cooling port sprays liquid toward the edge of the cavity. After the liquid absorbs heat and undergoes a phase change, it forms gas in the cooling channel. When in the second cooling condition, the second cooling port continuously injects turbulent liquid cooling medium into the cooling channel; When in the third cooling condition, the first control valve opens, and the gas in the positive pressure chamber enters the gas flow channel. The phase change gas in the first cooling condition is extracted by the suction effect of the vacuum generating chamber and mixed in the gas flow channel to form a mixed gas. The mixed gas enters the bubble generating chamber and forms micro-nano bubbles in the cooling flow channel.

[0010] Preferably, the bubble generating chamber includes a stream flow section and a collision section; the liquid flowing in from the cooling channel and the gas flowing in from the gas channel mix in the stream flow section and flow through the collision section before flowing out of the bubble generating chamber.

[0011] Preferably, a flow regulating component is provided in the cooling channel; the flow regulating component is configured to change the fluid flow cross-sectional area of ​​the second cooling port; when the flow regulating component is in a first expanded state, the channel cross-section of the second cooling port is rapidly expanded; when the flow regulating component is in a second contracted state, the channel cross-section of the second cooling port is gradually reduced.

[0012] Preferably, the flow regulating component includes symmetrically arranged swingable flow regulating plates, and a transmission pin is fixedly arranged on the flow regulating plates; a drive block is slidably arranged on the fixed mold, and a receiving groove is opened on the drive block, and the transmission pin is slidably arranged in the receiving groove.

[0013] Preferably, a one-way valve is provided between the cooling channel and the inlet end of the vacuum generating chamber; the one-way valve is directed from the cooling channel to the inlet end of the vacuum generating chamber, so as to allow the gas generated by the phase change in the cooling channel to enter the vacuum generating chamber unidirectionally under the action of the negative pressure suction effect.

[0014] Preferably, the pressure regulating assembly includes a cylinder with an inner cavity and a piston assembly that slides on the inner wall of the cylinder, the piston assembly dividing the interior of the cylinder into a non-communicating positive pressure chamber and a negative pressure chamber; the power unit includes a driving hydraulic cylinder, the driving hydraulic cylinder being drivenly connected to the piston assembly.

[0015] The beneficial effects of this invention are as follows: In the first cooling condition, the present invention sprays liquid cooling medium into the gap area at the edge of the mold cavity that is prone to overflow through the first cooling port; when the liquid medium comes into contact with the local high temperature mold wall, it induces flash phase change, and by means of the efficient transfer effect of latent heat of vaporization, a local cooling gradient field is constructed at the edge of the cavity. This thermodynamic mechanism causes the apparent viscosity of highly fluid thermoplastic polymer melts to increase before they reach the parting surface or the gap between the parts, thereby creating a physical flow barrier in situ along the potential overflow path.

[0016] This technical solution suppresses the lateral flow of the melt to a certain extent, avoids flash and burr defects in the injection molding process, and further avoids the subsequent manual trimming and mechanical polishing processes that are prone to causing microscopic scratches on the products. It significantly improves the surface molding quality, dimensional consistency and overall efficiency of the entire production cycle of micro precision injection molded parts. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the present invention; Figure 2 This is a gas path connection diagram according to an embodiment of the present invention; Figure 3 This is a front view of an embodiment of the present invention; Figure 4 for Figure 3 Sectional view along axis AA; Figure 5 for Figure 4 BB-direction sectional view; Figure 6 This is a schematic diagram of the structure of an embodiment of the present invention in the third cooling condition; Figure 7 This is a schematic diagram of the structure of a flow regulating component in one embodiment of the present invention; Figure 8 This is a schematic diagram of the operation of an embodiment of the present invention under the first cooling condition; Figure 9 This is a schematic diagram of the operation of an embodiment of the present invention under the second cooling condition; Figure 10 This is a schematic diagram of the operation of an embodiment of the present invention under the third cooling condition.

[0019] Explanation of reference numerals in the attached figures: 10. Moving mold; 20. Fixed mold; 21. Cavity; 30. Cooling channel; 31. First cooling port; 311. First water inlet pipe; 32. Second cooling port; 321. Second water inlet pipe; 40. Pressure regulating assembly; 41. Cylinder body; 42. Piston assembly; 43. Positive pressure chamber; 44. Negative pressure chamber; 50. Gas channel; 501. Vent port; 51. First control valve; 60. Vacuum generating chamber; 61. Inlet end; 62. Outlet end; 63. One-way valve; 70. Bubble generating chamber; 71. Stream beam section; 72. Collision section; 80. Flow regulating assembly; 81. Flow regulating plate; 82. Transmission pin; 83. Drive block; 84. Receiving groove. Detailed Implementation

[0020] As attached Figure 1-10The mold shown is suitable for small injection molded parts and mainly consists of a moving mold 10, a fixed mold 20, and a power device for controlling the global fluid timing. In the mold-locked state, the mating surfaces of the fixed mold 20 and the moving mold 10 enclose a cavity 21 for accommodating the polymer melt. To achieve dynamic temperature control of the cavity 21, a cooling channel 30 with high-pressure sealing properties is provided inside the fixed mold 20.

[0021] For the fluid power source configuration, the power unit is driven by a pressure regulating assembly 40. Specifically, the pressure regulating assembly 40 includes a cylinder 41 with a sealed inner cavity and a piston assembly 42 that slides on the inner wall of the cylinder 41. The piston assembly 42 physically divides the interior of the cylinder 41 into a non-communicating positive pressure chamber 43 and a negative pressure chamber 44, with the negative pressure chamber 44 connected to the cooling channel 30. The power unit is preferably a driving hydraulic cylinder, the output shaft of which is mechanically driven by the piston assembly 42. When the driving hydraulic cylinder performs linear extension and retraction, it drives the piston assembly 42 to reciprocate within the cylinder 41, thereby simultaneously achieving the compression and pressurization of the gas in the positive pressure chamber 43 and the negative pressure suction effect generated by the expansion of the volume of the negative pressure chamber 44 without adding an additional fluid pump source.

[0022] Understandably, when the moving mold 10 is driven by the power device to close with the fixed mold 20, the negative pressure chamber 44 becomes negative due to its increased volume, and the cooling channel 30 connected to the negative pressure chamber 44 also simultaneously forms a negative pressure environment. This allows the liquid cooling medium sprayed into the channel through the first cooling port 31 under the first cooling condition to instantly exceed its boiling point without changing its sensible heat, thereby triggering a flash phase change. This provides the thermodynamic conditions for the rapid cooling and in-situ solidification of the highly fluid resin melt at the edge of the cavity 21.

[0023] The cooling channel 30 has a first cooling port 31 and a second cooling port 32 inside. The jet axis of the first cooling port 31 is tilted at a specific angle and directly faces the edge of the cavity 21, that is, the fitting gap where overflow is likely to occur; the second cooling port 32 is arranged in the direction of the long axis of the cooling channel 30.

[0024] Specifically, the first cooling port 31 is connected to a first water inlet pipe 311, and the second cooling port 32 is connected to a second water inlet pipe 321, so as to inject liquid cooling medium into the cooling channel 30 in a controlled manner.

[0025] As can be seen from the above, the cooling channel 30 is under negative pressure, thus the boiling point of the liquid is correspondingly reduced. When the cooling liquid is injected from the first cooling port 31 towards the edge of the cavity 21, the liquid cooling medium, upon contact with the locally high-temperature inner wall of the mold, will cross the boiling point and undergo flash phase change because the ambient pressure is much lower than the saturated vapor pressure of the liquid at the current temperature. During the flash phase change, the liquid medium rapidly vaporizes and absorbs a large amount of latent heat of vaporization from the edge of the mold cavity 21, thereby forming a cooling gradient in this area and causing the edge mold temperature to drop sharply in a short time. This temperature change forces the apparent viscosity of the highly fluid resin melt flowing towards the mating gap to increase instantaneously and solidify and crystallize, thereby constructing a rigid physical flow barrier in situ at the overflow location, thus blocking the lateral flow path of the melt and effectively preventing the generation of flash and burrs in the injection molded products.

[0026] The fixed mold 20 is also provided with a gas flow channel 50, which is connected to the positive pressure chamber 43. A first control valve 51 is provided between the gas flow channel 50 and the positive pressure chamber 43. A vacuum generating chamber 60 is also provided in the gas flow channel 50. The vacuum generating chamber 60 includes an inlet end 61 and an outlet end 62. The inlet end 61 is connected to the cooling flow channel 30, and the outlet end 62 is connected to the gas flow channel 50 through a venting interface 501.

[0027] To prevent excessive water vapor from reducing the cooling effect during flash evaporation, a gas flow channel 50 is independently machined inside the fixed mold 20. The beginning of the gas flow channel 50 is connected to the aforementioned positive pressure chamber 43, and a first control valve 51 is connected in series on the connecting pipe. The middle section of the gas flow channel 50 houses a vacuum generating chamber 60 designed based on the Venturi principle. This vacuum generating chamber 60 has an inlet end 61 with a geometrically contracted cross-section and an outlet end 62 with an enlarged cross-section. The inlet end 61 is connected to the cooling flow channel 30, and the outlet end 62 extends downstream of the gas flow channel 50.

[0028] Understandably, when the compressed gas in the positive pressure chamber 43 flows through the vacuum generating chamber 60 at a certain speed, a sudden increase in velocity will occur in the throat region where the geometric cross-section of the vacuum generating chamber 60 contracts. According to the Venturi effect and fluid dynamics principles, the surge in velocity will lead to a decrease in static pressure in this region, thereby generating a negative pressure suction effect. This negative pressure suction effect can rapidly extract the large amount of water vapor generated by flash evaporation in the first cooling condition from the cooling channel 30, and carry the water vapor out from the outlet end 62 into the downstream gas channel 50. This process effectively prevents the accumulation of water vapor with low thermal conductivity on the inner wall of the channel and the formation of heat-insulating vents or air film insulation layers, ensuring a clean and unobstructed heat transfer boundary of the channel, thereby removing thermal resistance obstacles for subsequent heat exchange of the liquid cooling medium and maintaining the continuous cooling effect of the mold system.

[0029] Furthermore, to ensure the unidirectionality of fluid conduction and prevent backflow due to air resistance, a one-way valve is installed between the cooling channel 30 and the inlet end 61 of the vacuum generating chamber 60. The rated conduction direction of the one-way valve is defined as from the cooling channel 30 to the inlet end 61 of the vacuum generating chamber 60.

[0030] Preferably, the end of the gas flow channel 50 is also connected to the second cooling port 32; and a bubble generating chamber 70 is provided between the gas flow channel 50 and the second cooling port 32, and micro-nano bubbles are formed in the cooling flow channel 30 after the gas enters the bubble generating chamber 70 from the gas flow channel 50.

[0031] Preferably, the cooling channel 30 includes a first cooling condition, a second cooling condition, and a third cooling condition; When in the first cooling condition, the first cooling port 31 sprays liquid onto the edge of the cavity 21. After the liquid absorbs heat and undergoes a phase change, it forms gas in the cooling channel 30. When in the second cooling condition, a turbulent liquid cooling medium is continuously injected into the cooling channel 30 through the second cooling port 32; When in the third cooling condition, the first control valve 51 is opened, and the gas in the positive pressure chamber 43 enters the gas flow channel 50. The phase change gas remaining in the first cooling condition is extracted by the suction effect of the vacuum generating chamber 60 and mixed in the gas flow channel 50 to form a mixed gas. The mixed gas enters the bubble generating chamber 70 and forms micro-nano bubbles in the cooling flow channel 30.

[0032] Preferably, the bubble generating chamber 70 includes a flow beam section 71 and a collision section 72; the liquid flowing in from the cooling channel 30 and the gas flowing in from the gas channel 50 are mixed in the flow beam section 71 and flow through the collision section 72 before flowing out of the bubble generating chamber 70.

[0033] Preferably, a flow regulating component 80 is provided in the cooling channel 30; the flow regulating component 80 is configured to change the fluid flow cross-sectional area of ​​the second cooling port 32; when the flow regulating component 80 is in a first expanded state, the channel cross-section of the second cooling port 32 is suddenly expanded; when the flow regulating component 80 is in a second contracted state, the channel cross-section of the second cooling port 32 is gradually reduced.

[0034] When the liquid flows through the flow regulating component 80, the cross-section of the second cooling port 32 expands rapidly when the flow regulating component 80 is in the first expanded state. According to the fluid separation principle in fluid mechanics, when the fluid flows through the suddenly expanded flow channel, the flow velocity drops sharply and the static pressure rises. Strong boundary layer separation occurs between the fluid in the main flow area and the pipe wall, thereby generating dense wake vortices and intense turbulence. This turbulence can effectively break and tear apart the static heat transfer dead water zone on the inner wall of the cooling channel 30, improve the heat transfer coefficient of forced convection of the liquid phase, and enable the mold to achieve efficient and uniform macroscopic heat exchange under the second cooling condition.

[0035] When the flow regulating component 80 is in the second convergent state, the cross-section of the second cooling port 32 gradually shrinks, forming a convergent acceleration structure similar to a nozzle. According to the fluid continuity equation, the fluid flowing through this point will be forcibly compressed, increasing its velocity and generating extremely high fluid shear force at the throat of the flow channel. When the high-speed jet enters the bubble generating chamber 70, the fluid carrying greater kinetic energy will collide and undergo more intense physical shearing with the phase change gas or positive pressure air being drawn in. This high-frequency shearing and collision at the microscale can pulverize large-volume mixed gas, thereby generating a large number of uniformly sized and densely distributed micro-nano bubbles within the cooling channel 30.

[0036] Specifically, under the third cooling condition, micro-nano bubbles can provide sufficient heterogeneous nucleation surfaces for scale-forming ions in the liquid of the cooling channel 30, thereby effectively converting scale-forming ions into suspended particles, preventing them from forming scale on the inner wall of the cooling channel 30, thus inhibiting the rate of scale formation and reducing the frequency of mold downtime maintenance.

[0037] Understandably, since the gas in the gas channel 50 contains phase change vapor, and the bubbles of this phase change vapor condense and collapse faster than air bubbles when they come into contact with the low-temperature coolant in the cooling channel 30. During the rapid collapse of the phase change vapor bubbles, high-frequency micro-shock waves and micro-jets are released into the surrounding flow field. This micro-hydrodynamic energy directly bombards the relatively stable air bubbles around them, forcing them to undergo forced oscillation and further break into smaller nano-sized bubbles, thus achieving a secondary dispersion and uniform distribution of bubbles at the micro-scale. Compared to macro-dispersion, such as using mechanical agitators or static mixers in tubes, the micro-cavitation dispersion method through the collapse of phase change bubbles can achieve more uniform and dense gas-liquid mixing. At the same time, it effectively avoids the phenomenon of bubble aggregation into gas plugs or fluid stagnation in dead corners such as the ends, corners, or deep cavities of complex conformal water channels in the mold. This ensures that micro- and nano-bubbles can completely cover the entire inner wall of the cooling channel 30, thereby maximizing the comprehensive effectiveness of heterogeneous nucleation and scale prevention.

[0038] Preferably, the flow control assembly 80 includes symmetrically arranged swingable flow control plates 81, and a transmission pin 82 is fixedly arranged on the flow control plates 81; a drive block 83 is slidably arranged on the fixed mold 20, and a receiving groove 84 is opened on the drive block 83, and the transmission pin 82 is slidably arranged in the receiving groove 84.

[0039] Specifically, the moving mold 10 is provided with a first trigger block, and the fixed mold 20 is provided with a second force block. The second force block is connected to the drive block 83 in a transmission manner. When the moving mold 10 and the fixed mold 20 are in the mold closing position, the first trigger block pushes the second force block and the drive block 83, so that the flow regulating component 80 is in the first unfolded state. When the moving mold 10 and the fixed mold 20 are in the mold opening position, the flow regulating component 80 is in the second retracted state.

[0040] More specifically, the drive block 83 is acted upon by the elastic element, causing the flow regulating component 80 to tend to remain in the second contracted state.

[0041] The complete workflow of this embodiment is as follows: When the injection molding equipment completes the injection process and the highly fluid resin melt just arrives at the cavity 21, the system is in the first cooling state. At this time, the power unit drives the moving mold 10 and the pressure regulating component 40 simultaneously, causing the negative pressure chamber 44 to work, establishing and maintaining a specific negative pressure vacuum environment within the cooling channel 30. Subsequently, the first water inlet pipe 311 introduces the cooling medium, and the liquid cooling medium is sprayed at a specific angle through the first cooling port 31 onto the back edge of the cavity 21, where overflow is easily generated. Since the ambient pressure within the channel is lower than the saturated vapor pressure of the coolant at the current local high temperature, the droplets instantly cross the boiling point upon contact with the mold wall, undergoing a violent flash phase change. This process absorbs the latent heat of vaporization, causing the apparent viscosity of the resin melt at the edge of the cavity 21 to increase sharply and solidify, forming a physical flow barrier that blocks the path of melt outward flow, preventing the generation of flash and burrs. The large amount of water vapor generated during this phase change is temporarily stored within the cooling channel 30.

[0042] After a set holding time, the molding material in the cavity 21 needs to be uniformly cooled, and the system switches to the second cooling condition. The drive block 83 on the fixed mold 20 slides in a controlled manner, and through the receiving groove 84, it moves the transmission pin 82, forcing the flow regulating plate 81 of the flow regulating component 80 to swing outward to the first expanded state, causing the cross-section of the second cooling port 32 and the downstream channel to expand geometrically. At the same time, the second water inlet pipe 321 begins to continuously inject liquid cooling medium into the cooling channel 30 through the second cooling port 32 at a large flow rate. According to the principle of fluid separation, the coolant will induce boundary layer separation and turbulence when flowing through the suddenly expanded cross-section. This turbulence can effectively tear and break the static thermal boundary layer on the inner wall of the channel, greatly improving the heat transfer coefficient of the liquid phase forced convection, thereby implementing a large-area uniform heat replacement for the entire mold cavity 21, ensuring that the resin macromolecules in all parts of the injection molded part can crystallize and solidify synchronously and uniformly, and completely eliminating the risk of residual internal stress and warpage caused by temperature gradient.

[0043] After the injection molded part cools to a certain extent and enters the demolding step, the moving mold 10 separates from the fixed mold 20, and the system switches to the third cooling condition. At this time, the first control valve 51 opens, pushing the high-pressure compressed gas in the positive pressure chamber 43 into the gas flow channel 50. When the high-pressure gas flows through the vacuum generating chamber 60 at high speed, a deep negative pressure suction effect is generated at the inlet end 61 according to the Venturi effect, which forcibly extracts the phase change water vapor remaining in the cooling flow channel 30 in the first cooling condition and mixes it with air to form a two-component mixed gas.

[0044] Simultaneously, the drive block 83 slides in the opposite direction under elastic force, forcing the flow regulating plate 81 to swing to the second retracted state, causing the channel cross-section of the second cooling port 32 to gradually shrink to form a high-speed jet channel. The drawn-in mixed gas and the high-speed jet liquid medium collide and shear in the downstream bubble generating chamber 70, forming a dense cluster of micro- and nano-bubbles. After these micro- and nano-bubbles enter the cooling channel 30 with the fluid, they not only provide sufficient heterogeneous nucleation surfaces for scale-forming ions to inhibit initial scaling, but also achieve physical non-destructive cleaning of the cooling water circuit without stopping the machine for disassembly, ensuring the mold's long-term and good heat transfer performance.

[0045] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A mold suitable for small injection molded parts, comprising a moving mold, a fixed mold, and a power unit, wherein a cavity is formed between the fixed mold and the moving mold, and a cooling channel with a sealed space is provided on the fixed mold; characterized in that, The power unit is connected to a pressure regulating component, which includes a negative pressure chamber and a positive pressure chamber, with the negative pressure chamber connected to the cooling channel. The cooling channel is provided with a first cooling port facing the edge of the cavity and a second cooling port facing the length direction of the cooling channel. Both the first cooling port and the second cooling port can inject liquid cooling medium into the cooling channel. The fixed mold is also provided with a gas flow channel, which is connected to the positive pressure chamber. A first control valve is provided between the gas flow channel and the positive pressure chamber. A vacuum generating chamber is also provided in the gas flow channel. The vacuum generating chamber includes an inlet end and an outlet end. The inlet end is connected to the cooling flow channel, and the outlet end is connected to the gas flow channel.

2. A mold suitable for small injection molded parts according to claim 1, characterized in that, When the first control valve is opened, the gas in the positive pressure chamber enters the gas flow channel. The pressure at the inlet end of the vacuum generating chamber is higher than that at the outlet end, forming a negative pressure suction effect. The gas generated by the phase change in the cooling flow channel enters from the inlet end of the vacuum generating chamber and enters the gas flow channel from the outlet end.

3. A mold suitable for small injection molded parts according to claim 2, characterized in that, The gas flow channel is also connected to the second cooling port at its end; and a bubble generating chamber is provided between the gas flow channel and the second cooling port, and micro-nano bubbles are formed in the cooling flow channel after the gas enters the bubble generating chamber from the gas flow channel.

4. A mold suitable for small injection molded parts according to claim 3, characterized in that, The cooling channel is configured to switch between a first cooling condition, a second cooling condition, and a third cooling condition. When in the first cooling condition, the first cooling port sprays liquid toward the edge of the cavity. After the liquid absorbs heat and undergoes a phase change, it forms gas in the cooling channel. When in the second cooling condition, the second cooling port continuously injects turbulent liquid cooling medium into the cooling channel; When in the third cooling condition, the first control valve opens, and the gas in the positive pressure chamber enters the gas flow channel. The phase change gas in the first cooling condition is extracted by the suction effect of the vacuum generating chamber and mixed in the gas flow channel to form a mixed gas. The mixed gas enters the bubble generating chamber and forms micro-nano bubbles in the cooling flow channel.

5. A mold suitable for small injection molded parts according to claim 3, characterized in that, The bubble generating chamber includes a beam section and a collision section; The liquid flowing in from the cooling channel mixes with the gas flowing in from the gas channel in the beam section and flows out of the bubble generating chamber after passing through the collision section.

6. A mold suitable for small injection molded parts according to claim 2, characterized in that, A flow regulating component is provided inside the cooling channel; The flow control component is configured to change the fluid flow cross-sectional area of ​​the second cooling port; When the flow control component is in the first deployed state, the cross-sectional area of ​​the second cooling port is suddenly expanded; When the flow control component is in the second retracted state, the cross-sectional area of ​​the second cooling port gradually decreases.

7. A mold suitable for small injection molded parts according to claim 6, characterized in that, The flow control assembly includes symmetrically arranged swingable flow control plates, and a transmission pin is fixedly installed on the flow control plates; A drive block is slidably disposed on the fixed mold, and a receiving groove is provided on the drive block. The transmission pin is slidably disposed in the receiving groove.

8. A mold suitable for small injection molded parts according to claim 2, characterized in that, A one-way valve is provided between the cooling channel and the inlet end of the vacuum generating chamber; The one-way valve is directed from the cooling channel to the inlet of the vacuum generating chamber, allowing the gas generated by the phase change in the cooling channel to enter the vacuum generating chamber unidirectionally under the negative pressure suction effect.

9. A mold suitable for small injection molded parts according to claim 1, characterized in that, The pressure regulating assembly includes a cylinder with an inner cavity and a piston assembly that slides on the inner wall of the cylinder. The piston assembly divides the interior of the cylinder into a positive pressure chamber and a negative pressure chamber that are not in communication with each other. The power unit includes a drive hydraulic cylinder, which is connected to the piston assembly in a transmission manner.

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