Heat exchange injection mold, injection molding method and injection molding part

Abstract

The invention provides a heat exchange injection mold, an injection molding method and an injection molded part, the heat exchange injection mold comprises a movable mold, a fixed mold and a heat exchange device, a cavity is formed between the fixed mold and the movable mold, the parting surface of the cavity is provided with a first contour line on the movable mold, and the parting surface of the cavity is provided with a second contour line on the fixed mold; the heat exchange device comprises a compressor, a control valve, a gas-liquid separator and a heat exchange channel, the heat exchange channel is arranged close to the first contour line or the second contour line, the compressor communicates with the heat exchange channel to convey high-pressure liquid refrigerants, when the control valve is opened, the liquid refrigerants in the heat exchange channel are rapidly evaporated to enter the gas-liquid separator, and the gas-liquid separator communicates with the compressor. The heat exchange channel is arranged close to the parting surface, a large amount of heat is taken away through evaporation of a liquid refrigerant, the edge position of the parting surface of the mold is rapidly cooled, the overall average temperature is high, on the premise that the mold filling quality of an injection molding part is guaranteed, materials at the parting surface position are rapidly solidified, and flashes and burrs are effectively reduced.

Description

A heat exchange injection mold, injection molding method and injection molded part Technical Field

[0001] This application relates to the field of plastic molding technology, and in particular to a heat exchange injection mold, injection molding method and injection molded part. Background Technology

[0002] Injection molds are the primary tools for plastic molding. Existing injection molds are prone to producing flash and burrs when molding polyamide (PA, nylon), polypropylene (PP), or polyethylene (PE) products. Even with subsequent sanding, this is not only labor-intensive and time-consuming but also affects the product's appearance. For example, in large PP automotive interior parts, the flash is often thin and transparent, and manual removal can easily damage the product itself. PA materials utilize glass fiber reinforcement. Although glass fiber increases viscosity, its "wedge effect" can actually exacerbate mold wear, leading to increased gaps and further flash. While increasing processing precision and mold fit to reduce gaps can improve venting, it can also prevent air from escaping during high-speed injection molding, causing air to become trapped in the molded part and preventing proper filling. Lowering the mold temperature can result in poor filling and defects in larger injection parts.

[0003] Chinese patent application CN223790918U, entitled "An Automated Injection Mold for Rubber Bushings," discloses an automated injection mold for rubber bushings. The mold includes a mounting frame, a control terminal mounted on one side of the frame, an upper mold mounted on one end, and a lower mold mounted on the other. Two support plates are fixedly connected to one side of the inner wall of the mounting frame, and a stationary mold is fixedly connected to one end of each support plate. This automated injection mold for rubber bushings uses a stationary mold, upper mold, and lower mold to form a complete injection mold for injection molding. When the upper and lower molds separate, the stationary mold, together with the upper mold, creates a reverse push on the molded part, causing the part to be extruded from the upper mold's forming groove. A circulating cooler then circulates cooling water into a flow channel to cool the stationary mold, ensuring it remains at a constant temperature and preventing high-temperature operation from affecting the quality of the molded part. However, it does not consider the issues of flash and burrs; the overall temperature drop of the mold can cause molding difficulties and poor filling.

[0004] Chinese patent application CN223763721U, entitled "A Cooling Mechanism for an Injection Mold," discloses a cooling mechanism for an injection mold. This utility model includes a base plate and a water storage tank. A lower mold and a support plate are fixedly mounted on the upper surface of the base plate. A cylinder is installed at the top of the support plate, and the bottom of the cylinder is fixedly connected to the upper mold. A feeding pipe is fixedly connected to the upper surface of the upper mold. An inner cavity is opened inside the lower mold, and a circulation pipe is fixedly installed inside the inner cavity. This utility model addresses the overall mold temperature issue, primarily cooling after filling and not during filling. Therefore, it does not solve the problems of flash and burrs. Summary of the Invention

[0005] This application provides a heat exchange injection mold, an injection method, and an injection molded part, to at least solve the technical problems of flash and burrs existing in the prior art.

[0006] According to a first aspect of this application, a heat exchange injection mold is provided, including a moving mold, a fixed mold, and a heat exchange device. A cavity is formed between the fixed mold and the moving mold. The parting surface of the cavity has a first contour line on the moving mold and a second contour line on the fixed mold. The heat exchange device includes a compressor, a control valve, a gas-liquid separator, and a heat exchange channel. The heat exchange channel is located near the first or second contour line. The compressor is connected to the heat exchange channel so that the compressor can deliver high-pressure liquid refrigerant to the heat exchange channel. The heat exchange channel is provided with a control valve so that when the control valve is opened, the liquid refrigerant in the heat exchange channel evaporates rapidly and enters the gas-liquid separator. The gas-liquid separator is connected to the compressor to provide gaseous refrigerant to the compressor.

[0007] Compared with existing technologies, the heat exchange injection mold of this application has the following beneficial effects: the evaporation of liquid refrigerant can remove a large amount of heat to achieve rapid cooling, causing the temperature of the local area near the first contour line or the second contour line of the injection mold to drop rapidly, but the overall average temperature of the mold is relatively high, which does not affect the filling and has little impact on the overall quality of the injection molded part. However, the temperature near the first contour line or the second contour line is lower, and the material can cool down and solidify rapidly, making it less likely for burrs and flash to be generated at the parting surface. In this way, flash and burrs can be reduced while ensuring the quality of the injection molded part. For some injection molded parts, no flash and burrs are generated, avoiding subsequent manual polishing, making the product appearance smoother and improving the overall quality.

[0008] In one embodiment, the fixed mold has an injection port, and the heat exchange channel of the heat exchange device is located in the moving mold. The injection port of the fixed mold is connected to the injection molded part, and the temperature is relatively high and needs to be maintained at a certain temperature. The moving mold moves relative to the fixed mold to open and close the mold. Lowering the temperature of the moving mold can achieve gradual solidification from the moving mold to the fixed mold. Especially for products with higher shrinkage, it can maintain the fluidity on one side during solidification, compensate for areas with large shrinkage, and achieve better solidification effect.

[0009] In one embodiment, the moving mold is provided with a heat exchange groove, and a heat exchange tube is provided inside the heat exchange groove. The heat exchange groove is arranged around or along the first contour line, and a heat exchange plate made of a high thermal conductivity material is covered on the heat exchange groove. The high thermal conductivity material has better heat conduction performance, resulting in faster temperature drop. The heat exchange tube is easy to install and has better sealing performance, preventing refrigerant leakage.

[0010] In one embodiment, the heat exchange device includes a condenser and a receiver. The compressor is connected to the condenser, the condenser is connected to the receiver, and the receiver is connected to the heat exchange channel. In this way, the compressor can operate continuously, and excess liquid refrigerant is stored in the receiver. When needed, opening the relevant control valve quickly delivers the liquid refrigerant to the heat exchange channel, where it rapidly evaporates and absorbs heat, completing the heat exchange.

[0011] In one embodiment, the heat exchange tube includes a low-pressure tube and a high-pressure tube, which are connected by multiple microporous tubes. The high-pressure tube is connected to a piston cylinder, allowing changes in the space within the piston cylinder to alter the pressure in the high-pressure tube. Thus, the low-pressure tube can absorb heat through evaporation, while the high-pressure tube can store refrigerant. When the low-pressure tube needs to stop absorbing heat, the piston cylinder can be used to draw refrigerant from the high-pressure tube, achieving rapid pressure reduction and minimizing or preventing refrigerant from entering the low-pressure tube. The multiple microporous tubes also ensure more uniform refrigerant evaporation at different locations within the low-pressure tube, resulting in smaller temperature differences between different locations.

[0012] In one embodiment, a cold water tank is provided outside the condenser to cool the condenser via water cooling. The first end of the cold water tank is connected to a water source, and the second end is connected to a water cooling channel in the moving or stationary mold. The cold water tank can increase the liquefaction rate of the refrigerant in the condenser, improve the compressor's efficiency, and raise the water cooling temperature in the water cooling channel, thus reducing deformation of the injection molded parts during the cooling process.

[0013] In one possible implementation, the condenser is cooled by a fan, which is a highly efficient and cost-effective cooling method.

[0014] In one embodiment, carbon dioxide is used as the refrigerant. Carbon dioxide is not only more environmentally friendly, but also has better heat exchange performance, which can make the temperature near the first or second contour line lower.

[0015] According to a second aspect of this application, a heat exchange injection molding method is provided, comprising at least the following steps: S1, after the injection mold is closed, before or during injection by the injection molding machine, the evaporation of the refrigerant in the heat exchange channel of the heat exchange device removes the heat from the edge of the mold cavity parting surface, causing the temperature at the edge of the mold cavity parting surface to drop rapidly; S2, after the injection molding machine completes the filling of the mold cavity, the water cooling channel is opened, the injection molded part begins to cool and solidify, the cavity pressure holding is completed, and the refrigerant in the heat exchange channel is stopped from evaporating by a control valve; S3, after solidification is completed, the mold is opened to eject the injection molded part, and the mold is closed.

[0016] Because the steel used in the mold has poor thermal conductivity, the rapid evaporation of the refrigerant can cause the local temperature to drop quickly. The injection molding machine has a high-pressure filling speed, and when the melt reaches the parting surface of the cavity, the lower temperature causes the melt to solidify quickly, avoiding the generation of flash and burrs, reducing subsequent removal processes, and making the product more aesthetically pleasing.

[0017] In one embodiment, the water in the water-cooling channel first cools the condenser of the heat exchange device, and then is transported to the moving mold or fixed mold to cool the injection molded part. This improves the compressor's working efficiency, and the cooling of the injection molded part is more gradual, reducing warping deformation during the shrinkage process of the injection molded part, resulting in more stable product quality.

[0018] According to a third aspect of this application, an injection molded part is provided, manufactured using the aforementioned heat exchange injection mold or heat exchange injection molding method. This injection molded part has fewer burrs and flash, and a smoother appearance.

[0019] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0020] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, wherein: in the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0021] Figure 1 shows a three-dimensional schematic diagram of the composition structure of the heat exchange injection mold according to an embodiment of the present application; Figure 2 shows a top view of the heat exchange injection mold according to an embodiment of the present application; Figure 3 shows a schematic diagram of the moving mold part of the heat exchange injection mold according to an embodiment of the present application; Figure 4 shows a cross-sectional schematic diagram of the heat exchange injection mold according to an embodiment of the present application perpendicular to the first direction; Figure 5 shows a cross-sectional schematic diagram of the heat exchange injection mold according to an embodiment of the present application perpendicular to the second direction; Figure 6 shows a schematic diagram of the heat exchange channel structure of the heat exchange injection mold according to an embodiment of the present application; Figure 7 shows a schematic diagram of an injection molded part produced by the heat exchange injection mold according to an embodiment of the present application; Figure 8 shows a three-dimensional schematic diagram of the heat exchange injection mold according to another embodiment of the present application; Figure 9 shows a cross-sectional schematic diagram of the heat exchange injection mold according to another embodiment of the present application perpendicular to the second direction; Figure 10 shows a partially enlarged schematic diagram of point A in Figure 9; Figure 11 shows a schematic diagram of the heat exchange channel structure of the heat exchange injection mold according to another embodiment of the present application.

[0022] Explanation of the numbers in the diagram: X, first direction; Y, second direction; Z, third direction; 1, moving mold; 2, fixed mold; 3, heat exchange device; 4, cavity; 5, parting surface; 6, first contour line; 7, second contour line; 8, injection port; 9, compressor; 10, control valve; 11, gas-liquid separator; 12, heat exchange channel; 13, heat exchange tank; 14, heat exchange tube; 15, heat exchange plate; 16, low-pressure pipe; 17, high-pressure pipe; 18, microporous tube; 19, piston cylinder; 20, condenser; 21, liquid reservoir; 22, cold water tank; 23, water cooling channel; 24, fan; 25, injection molded part; 26, first edge; 27, low-pressure tank; 28, high-pressure tank; 29, microporous plate; 30, hose. Detailed Implementation

[0023] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Example 1: As shown in Figures 1, 3, and 5, this example provides a heat exchange injection mold. As shown in Figure 1, the mold includes a moving mold 1, a fixed mold 2, and a heat exchange device 3. A cavity 4 is formed between the fixed mold 2 and the moving mold 1. The parting surface 5 of the cavity 4 has a first contour line 6 on the moving mold 1, and a second contour line 7 on the fixed mold 2. When the moving mold 1 opens, it moves relative to the injection molded part 25. When the fixed mold 2 opens, it does not move relative to the injection molded part 25, or the injection molded part 25 is ejected by an ejector pin. The moving mold 1 is usually a concave mold, and the fixed mold 2 is usually a convex mold. If necessary, the fixed mold 2 can also move and is not absolutely stationary. In some embodiments, the moving mold 1 and the fixed mold 2 can be horizontally positioned. The first direction is the left-right direction, the second direction is the front-back direction, and the third direction is the up-down direction.

[0025] Specifically, the moving mold 1 and the fixed mold 2, when closed, enclose a cavity 4 for molding the injection molded part 25. The parting surface 5 is the surface where the moving mold 1 and the fixed mold 2 contact each other. The first contour line 6 and the second contour line 7 are the edge lines of the cavity 4, the moving mold 1, and the fixed mold 2 at the parting surface 5. The first contour line 6 and the second contour line 7 are not necessarily actual contours, but theoretical contour lines. Theoretically, the first contour line 6 and the second contour line 7 coincide, but in reality, there is a gap between the moving mold 1 and the fixed mold 2, so they do not coincide. The first contour line 6 and the second contour line 7 are also the locations where flash and burrs are most likely to occur. It should be understood that although this embodiment and the accompanying drawings mainly show the case where the heat exchange channel 12 is set close to the first contour line 6, in actual applications, depending on the mold structure, the heat exchange channel 12 can also be set close to the second contour line 7, that is, the heat exchange device is set on the fixed mold 2, or simultaneously on the moving mold 1 and the fixed mold 2, as long as it can achieve local rapid cooling of the edge of the parting surface 5.

[0026] As shown in Figures 1, 2, and 3, the heat exchange device 3 includes a compressor 9, a control valve 10, a gas-liquid separator 11, and a heat exchange channel 12. The heat exchange channel 12 is positioned close to the first contour line 6 or the second contour line 7, with the distance controlled within 5 mm; for larger injection-molded parts 25, this distance can be controlled within 10 mm. The compressor 9 is connected to the heat exchange channel 12, enabling it to deliver high-pressure liquid refrigerant to the channel. The heat exchange channel 12 is equipped with the control valve 10, which, when opened, causes the liquid refrigerant in the channel to rapidly evaporate and enter the gas-liquid separator 11. The gas-liquid separator 11 is connected to the compressor 9, providing it with gaseous refrigerant. In this embodiment, the compressor 9 serves as a power source, continuously compressing the gaseous refrigerant into a high-temperature, high-pressure state. The control valve 10, acting as a switching element, is located at the inlet or on the pipeline of the heat exchange channel 12. Control valve 10 can be an electronic expansion valve, controlled by a control circuit. Electronic expansion valves are relatively expensive. In some embodiments, control valve 10 can also use two shut-off valves. The first shut-off valve can be located between the heat exchange channel 12 and the gas-liquid separator 11, and the second shut-off valve can be located between the heat exchange channel 12 and the compressor 9, used in conjunction with a microporous tube 18. The microporous tube 18 has a throttling function and can replace the expansion valve. When the mold is closed in preparation for injection, control valve 10 opens, the second shut-off valve opens, and the high-pressure liquid refrigerant (such as carbon dioxide or other environmentally friendly refrigerant) stored in the system rapidly flows into the heat exchange channel 12. Because the heat exchange channel 12 is close to the contour line of the parting surface 5, the first shut-off valve opens, the pressure inside the heat exchange channel 12 decreases, and the liquid refrigerant undergoes a violent phase change evaporation within the channel, absorbing a large amount of heat. This heat absorption process is extremely fast, and can significantly reduce the temperature at the edge of the parting surface 5 in a very short time.

[0027] This design achieves a balance between rapid localized cooling and a relatively high overall average temperature. Since the mold body is typically made of steel, its thermal conductivity is limited, and the heat absorption process of the refrigerant evaporation is mainly concentrated near the heat exchange channel 12 close to the contour line. Heat transfer from the mold center to the edge takes time. Therefore, while the melt rapidly cools and solidifies at the edge of the parting surface 5, preventing flash formation, most of the mold cavity 4 maintains a relatively high temperature, and the melt flowability remains unaffected. This avoids problems such as poor filling and material shortages caused by overall cooling.

[0028] As shown in Figures 1, 2, and 3, in this embodiment, the fixed mold 2 is provided with an injection port 8, and the heat exchange channel 12 of the heat exchange device 3 is located in the moving mold 1. The injection port 8 is used to connect to the injection molding machine nozzle and inject melt into the cavity 4. Located in the moving mold 1, the heat exchange channel 12 facilitates piping arrangement, and the lower temperature of the moving mold 1 helps the molded part 25 remain on the moving mold 1 side for ejection during mold opening. Furthermore, for taller molded parts 25, the temperature on the moving mold 1 side is lower while the temperature on the fixed mold 2 side is relatively higher, allowing for sequential solidification from the moving mold 1 to the fixed mold 2. This facilitates compensation for areas with significant shrinkage, improving molding quality.

[0029] Furthermore, the heat exchange device 3 is equipped with a condenser 20 and a liquid receiver 21. The compressor 9 is connected to the condenser 20, the condenser 20 is connected to the liquid receiver 21, and the liquid receiver 21 is connected to the heat exchange channel 12. Specifically, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 9 first enters the condenser 20, where it is cooled and liquefied into high-pressure liquid refrigerant, which is then stored in the liquid receiver 21. The liquid receiver 21 acts as a buffer and storage device, ensuring that there is a sufficient supply of liquid refrigerant to the heat exchange channel 12 for evaporation and heat absorption when the second shut-off valve of the control valve 10 is opened. After evaporation in the heat exchange channel 12, the gaseous refrigerant enters the gas-liquid separator 11, where any entrained droplets are separated, and then it returns to the compressor 9, forming a complete refrigeration cycle. This cycle system has a compact structure and can continuously and stably provide the cooling capacity required for rapid local cooling of the mold.

[0030] Example 2: As shown in Figures 4, 5, and 6, this example is a further refinement of Example 1, focusing on the detailed arrangement of the heat exchange channel 12 on the moving mold 1. In this example, the moving mold 1 is provided with a heat exchange groove 13, within which a heat exchange tube 14 is installed. The heat exchange groove 13 is arranged around or along the first contour line 6, and a heat exchange plate 15 made of a highly thermally conductive material covers the heat exchange groove 13. Specifically, the heat exchange groove 13 is a groove structure milled into one side of the parting surface 5 of the moving mold 1. The orientation of the heat exchange groove 13 is flexible and adaptable to different cavity shapes 4. When the cavity 4 is a rotating structure, the heat exchange groove 13 can be designed as a closed ring around the first contour line 6, thereby uniformly cooling the edge of the parting surface 5 in the entire circumferential direction; when the cavity 4 is an irregular or elongated structure, the heat exchange groove 13 can extend along the orientation of the first contour line 6, focusing on targeted cooling of the edge sections prone to flash. This arrangement, "around" or "along" the first contour line 6, ensures that the distance between the heat exchange source and the high-burst area (first contour line 6) is minimized, reducing thermal resistance on the heat conduction path and thus achieving rapid heat transfer. This embodiment uses a four-part injection molding method; therefore, the heat exchange channel 12 is also set for four injection molded parts 25. Since the first contour line 6 is annular, four annular structures are required. To facilitate the setting of the heat exchange groove 13, two heat exchange channels 12 are connected in series, simplifying the setting of the heat exchange tube 14.

[0031] As shown in Figures 4, 5, and 6, the heat exchange tube 14, serving as a carrier for refrigerant flow, is embedded within the heat exchange groove 13. The shape of the heat exchange tube 14 is adapted to the heat exchange groove 13, and the tube wall of the heat exchange tube 14 is in close contact with the heat exchange plate 15. The tube wall of the heat exchange tube 14 does not need to be in close contact with the inner wall of the heat exchange groove 13, or it may be filled with insulation material. This ensures the mold temperature and reduces the temperature of the heat exchange plate 15. The opening of the heat exchange groove 13 is covered with a heat exchange plate 15 made of a highly thermally conductive material. This heat exchange plate 15 seals the heat exchange groove 13. In some embodiments, the heat exchange tube 14 is not used; the heat exchange groove 13 is used directly as the heat exchange channel 12. The heat exchange plate 15 prevents refrigerant leakage, and more importantly, it significantly increases the contact area between the heat exchange device 3 and the mold body. By setting up heat exchange plates 15, the refrigerant evaporates and absorbs heat inside the heat exchange tubes 14, and the cooling capacity is rapidly transferred to highly thermally conductive materials (such as copper plates or aluminum alloy plates). Since the thermal conductivity of these materials is much higher than that of mold steel, the heat exchange plates 15 can act like "heat dissipation fins," rapidly and evenly spreading the cooling capacity throughout the entire heat exchange tank 13 area, and then efficiently transferring it to the mold wall near the first contour line 6. This structural design cleverly solves the requirement of "rapid and uniform cooling of local mold areas," ensuring both sealing and significantly improving heat exchange efficiency, providing reliable hardware support for the rapid solidification of the parting surface 5 edge.

[0032] Example 3: As shown in Figures 4, 5, and 6, this example is a further refinement of Example 2, mainly focusing on the internal fine structure of the heat exchange tube 14. The heat exchange tube 14 includes a low-pressure tube 16 and a high-pressure tube 17. The low-pressure tube 16 and the high-pressure tube 17 are connected by multiple microporous tubes 18. The high-pressure tube 17 is connected to a piston cylinder 19, allowing changes in the space of the piston cylinder 19 to alter the pressure of the high-pressure tube 17. The through holes of the microporous tubes 18 are processed by laser or electrical discharge machining, with a diameter less than or equal to 0.1 mm. For larger injection molded parts 25, the diameter can be appropriately increased to 0.3 mm. The high-pressure tube 17 is connected to the compressor 9 via a second shut-off valve, and the low-pressure tube 16 is connected to the gas-liquid separator 11 via a first shut-off valve. The piston cylinder 19 and the compressor 9 are located at opposite ends of the high-pressure tube 17, balancing the pressure on both sides.

[0033] Specifically, the low-pressure pipe 16 serves as the evaporation end, directly participating in the heat exchange of the mold; the high-pressure pipe 17 serves as the liquid storage end, storing the high-pressure liquid refrigerant. The microporous pipe 18 acts as a throttling element, connecting the high-pressure pipe 17 and the low-pressure pipe 16. When the first shut-off valve of the control valve 10 is opened and heat absorption is required, the high-pressure liquid refrigerant in the high-pressure pipe 17 is uniformly injected into the low-pressure pipe 16 through multiple microporous pipes 18 under the action of pressure difference. Due to the extremely small pore size of the microporous pipes 18, the refrigerant pressure drops sharply after entering the low-pressure pipe 16, resulting in violent flash evaporation and absorption of a large amount of heat. In particular, by setting "multiple" microporous pipes 18 and distributing them at intervals along the extension direction of the heat exchange pipe 14 (i.e., along the direction of the first contour line 6), it can be ensured that the refrigerant simultaneously evaporates and absorbs heat at different positions in the low-pressure pipe 16. This multi-point injection structure effectively avoids the problem of uneven refrigerant distribution that may be caused by traditional single-point liquid supply, ensures consistent cooling at all edges of the parting surface 5, and prevents internal stress or deformation of the injection molded part 25 due to excessive local temperature difference.

[0034] Furthermore, the piston cylinder 19 addresses the lag issue in traditional refrigeration systems when liquid supply is stopped. When filling is complete and rapid cooling of the parting surface 5 edge needs to be stopped, the piston cylinder 19 actuates, for example, by extending or retracting the piston rod to increase the internal volume connected to the high-pressure pipe 17, thereby rapidly reducing the pressure within the high-pressure pipe 17. Specifically, the piston cylinder 19 can be configured to rapidly increase the volume of the high-pressure pipe 17 and reduce its internal pressure when heat absorption needs to be stopped, thereby reducing or even eliminating the pressure difference between the high-pressure pipe 17 and the low-pressure pipe 16, thus blocking the flow of refrigerant through the microporous pipe 18 to the low-pressure pipe 16. This method of directly changing pressure through a mechanical structure offers a faster response and higher control precision compared to simply relying on a solenoid valve to close the pipeline. It enables "instant stop," avoiding overcooling caused by continued evaporation of residual refrigerant, ensuring precise control of the mold temperature field, and preventing deformation of the injection molded part 25 due to rapid cooling.

[0035] Example 4: As shown in Figures 4, 5, and 6, this example provides a heat exchange injection molding method. This method is applicable to the heat exchange injection molds described in the above examples, or mold equipment with the same principle. Through specific timing control, this method achieves the dual effects of preventing flash and ensuring quality.

[0036] The method specifically includes the following steps: Step S1, after the injection mold is closed, before or at the start of injection, the evaporation of the refrigerant in the heat exchange channel 12 of the heat exchange device 3 removes heat from the edge of the parting surface 5 of the mold cavity 4, causing the temperature at the edge of the parting surface 5 of the mold cavity 4 to drop rapidly. Specifically, after the moving mold 1 and the fixed mold 2 close to form the cavity 4, the injection molding machine nozzle prepares to inject high-temperature melt into the cavity 4. At this time, the control system issues a command to open the second shut-off valve of the control valve 10, and the high-pressure liquid refrigerant stored in the system quickly flows into the heat exchange channel 12 near the first contour line 6 or the second contour line 7. Opening the first shut-off valve of the control valve 10 causes a sudden drop in pressure in the heat exchange channel 12, and the liquid refrigerant undergoes a violent phase change evaporation, absorbing a large amount of latent heat of vaporization. Because the heat exchange channel 12 is set close to the edge of the parting surface 5, the heat is quickly removed, resulting in a significant drop in the mold temperature at the edge of the parting surface 5 in a very short time. This "pre-cooling" or "instant cooling" strategy is crucial. When the high-temperature melt subsequently fills to the edge of cavity 4, it comes into contact with the pre-cooled parting surface 5. The melt quickly loses its fluidity and solidifies, thus preventing it from squeezing into the tiny gap between the moving mold 1 and the fixed mold 2, eliminating flash at the source. Simultaneously, because the cooling time is extremely short and concentrated at the edge, the temperature of the mold body does not drop significantly, ensuring the fluidity of the melt in the main body of cavity 4 and avoiding short shots or material shortages caused by excessively low overall temperature. When the mold is more than half full, the second shut-off valve of control valve 10 can be closed first to prevent continuous evaporation and heat absorption after filling, which could cause shrinkage and deformation of the injection molded part 25.

[0037] In step S2, the injection molding machine completes the filling of the mold cavity 4 and enters the pressure holding state. The water cooling channel 23 is opened, and the injection molded part 25 begins to cool and solidify. After the cavity 4 is completely filled with melt, the control system closes the second shut-off valve of the control valve 10, cutting off the refrigerant supply to the heat exchange channel 12. The remaining small amount of liquid refrigerant is used for cooling. After the pressure holding is completed, the first shut-off valve of the control valve 10 is closed, and the second shut-off valve of the control valve 10 is opened. The compressor 9 compresses the gaseous refrigerant and delivers it to the heat exchange channel 12. At this time, the heat exchange channel 12 is in a high-pressure heating state, and the heat exchange channel 12 contains high-temperature liquid refrigerant or high-pressure gaseous refrigerant. The gaseous refrigerant begins to liquefy or the liquid refrigerant cools down to release heat. At this time, the compressor 9 can continue to work, compressing the gaseous refrigerant and delivering it to the condenser 20. After liquefaction in the condenser 20, it is stored. Some refrigerant can also enter the heat exchange channel 12 to prepare for the next cycle. At the same time, the pre-set water cooling channel 23 inside the starting mold 1 or the fixed mold 2 is opened to cool the injection molded part 25 as a whole.

[0038] In this process, the water in the water-cooling channel 23 first cools the condenser 20 of the heat exchange device 3, and then is transported to the moving mold 1 or the fixed mold 2 to cool the injection molded part 25. Specifically, the cooling water first flows through the cold water tank 22 surrounding the condenser 20, absorbing the heat emitted by the condenser 20, causing the gaseous refrigerant in the condenser 20 to liquefy rapidly, improving the condensation efficiency and the working efficiency of the compressor 9. After absorbing heat, the temperature of the cooling water will rise, becoming warm water, and then this warm water enters the water-cooling channel 23 of the mold to cool the injection molded part 25. This design has a dual advantage: on the one hand, by using water cooling to assist the condenser 20 in heat dissipation, the high efficiency and stability of the refrigeration cycle are ensured; on the other hand, the temperature of the cooling water entering the mold is moderate, avoiding thermal stress concentration and warping deformation of the injection molded part 25 caused by excessive temperature difference, achieving gentle cooling, and further improving product quality.

[0039] Step S3: After solidification, the mold opens to eject the injection part 25, and then closes the mold. Through continuous cooling in the water cooling channel, the temperature of the injection part 25 drops below the demolding temperature, completing solidification and shaping. The mold then opens, and the ejection mechanism ejects the injection part 25 from the cavity, completing one production cycle. The mold closes again, preparing for the next injection cycle.

[0040] By coordinating the above steps in sequence, the method in this embodiment achieves an organic combination of "local rapid cooling to prevent flash" and "overall slow cooling to ensure quality," resolving the contradiction in traditional processes where flash and poor filling are difficult to address simultaneously.

[0041] Example 5: As shown in Figure 7, this example provides an injection molded part 25, which is manufactured using the heat exchange injection mold or the heat exchange injection molding method described in any of the above embodiments. The injection molded part 25 is a cylindrical component, with its first edge 26 forming a ring at the edge of its outer surface and located at the parting surface 5. Therefore, conventional mold production easily produces flash and burrs. The first edge 26 theoretically coincides with the first contour line 6 and the second contour line 7.

[0042] Specifically, during the molding process of the injection molded part 25, the edge of the mold parting surface undergoes localized rapid cooling before the melt arrives, causing the melt to solidify instantly upon contact with the parting surface edge, preventing it from being squeezed into the mating gap between the moving and fixed molds. Therefore, the injection molded part 25 of this application has significantly different appearance characteristics from traditional injection molded parts. Its parting surface edge is smooth and flat, with virtually no flash or burrs commonly found in conventional injection molding processes. Traditional processes often struggle to remove thin or transparent flash, easily damaging the product body during subsequent polishing processes. However, the injection molded part 25 obtained in this embodiment completely eliminates this risk, resulting in extremely high product appearance integrity. No subsequent deburring and polishing processes are required, significantly improving production efficiency and product yield.

[0043] Furthermore, because the mold body maintains a high average temperature during the filling stage, the melt has good fluidity, the internal structure of the injection molded part 25 is dense, and there are no obvious shrinkage cavities or bubble defects, resulting in stable overall quality. It should be understood that the material of the injection molded part 25 is not limited; it can be polypropylene (PP), polyamide (PA), polyethylene (PE), or other thermoplastic materials. As long as it is formed using the aforementioned mold or method with localized rapid cooling function, and thus achieves a product with no flash at the parting surface, it falls within the scope of protection of this invention.

[0044] Example 6: As shown in Figures 1, 2, and 3, this example is a variation of Example 1, mainly focusing on the cooling method of the condenser 20 and the utilization path of the cooling water. In this example, a cold water tank 22 is provided outside the condenser 20 to cool the condenser 20 by water cooling. The first end of the cold water tank 22 is connected to a water source, and the second end of the cold water tank 22 is connected to the water cooling channel 23 of the moving mold 1 or the fixed mold 2.

[0045] Specifically, the cold water tank 22, as an independent heat exchange container, is internally designed to accommodate the condenser 20. The condenser 20 can be completely submerged in the water of the cold water tank 22, or it can pass through the cold water tank 22 via coils to achieve sufficient heat exchange. The first end of the cold water tank 22 serves as the water inlet, connected to an external water source (such as a cooling tower or tap water network) via a pipeline; the second end of the cold water tank 22 serves as the water outlet, connected to the inlet of a pre-set water-cooling channel 23 inside the moving mold 1 or the fixed mold 2 via a pipeline.

[0046] This connection method creates a unique cooling water flow path: low-temperature cooling water first enters the cold water tank 22, absorbing a large amount of heat dissipated by the condenser 20 during operation. This process raises the water temperature around the condenser 20, but compared to air cooling alone, water has a higher specific heat capacity and can more efficiently remove heat, thus significantly increasing the liquefaction rate of the high-temperature, high-pressure gaseous refrigerant inside the condenser 20, reducing the condensing pressure, and consequently improving the operating efficiency and energy efficiency ratio of the compressor 9.

[0047] More importantly, the cooling water, after absorbing heat from the condenser 20, will rise in temperature, becoming lukewarm. This lukewarm water then flows out from the second end of the cold water tank 22 and is directly delivered to the water cooling channel 23 of the mold to cool the injection molded part 25. In traditional injection molding cooling systems, low-temperature cooling water (e.g., 10℃-25℃) is often used directly to cool the mold. This can easily cause a sudden drop in the temperature of the mold cavity wall 4, resulting in excessive thermal stress on the injection molded part 25 during cooling, leading to defects such as warping, deformation, or shrinkage cavities. In this embodiment, the lukewarm water, after being "preheated" by the condenser 20 (e.g., its temperature rises to 25℃-55℃), has a more moderate temperature. When it enters the mold water cooling channel 23, it can cool the injection molded part 25 at a relatively gentle cooling rate, effectively avoiding thermal shock caused by excessive temperature differences. This design cleverly achieves "dual use of water," solving both the efficient heat dissipation problem of the condenser 20 and optimizing the cooling process of the injection molded part 25. While ensuring production efficiency, it significantly improves the molding quality and dimensional stability of the product.

[0048] Example 7: As shown in Figure 8, this example is a variation of Example 1, mainly describing the cooling method of the condenser 20. In this example, the condenser 20 is cooled by a fan 24.

[0049] Specifically, a fan 24 is installed near the condenser 20, and the fan 24 can be fixed to the bracket of the condenser 20 or the frame of the mold equipment. When the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 9 enters the condenser 20, the fan 24 starts, forcing air to flow over the heat dissipation surface (such as heat dissipation fins or coils) of the condenser 20, accelerating air convection, thereby removing the heat dissipated by the condenser 20, and cooling and liquefying the gaseous refrigerant into high-pressure liquid refrigerant. The condenser 20 is connected to the heat exchange channel 12 of the moving mold 1 through a flexible hose 30, allowing the condenser 20 and the compressor 9 to be fixed to the ground without affecting the movement of the moving mold 1.

[0050] Compared to the water-cooling method described in Example 6, the air-cooling method used in this embodiment has the advantages of simple structure and low cost. The air-cooling system eliminates the need for a cold water tank 22, a circulating water pump, and complex inlet and outlet pipes, greatly simplifying the overall system structure and reducing manufacturing and maintenance costs. This implementation method is particularly suitable for applications with relatively low cooling efficiency requirements, suitable ambient temperatures, or scarce water resources. For example, in some small injection molding production workshops or mobile injection molding equipment, air-cooling is more advantageous due to its convenience. It should be understood that although the heat exchange efficiency of air-cooling is generally lower than that of water-cooling and is greatly affected by ambient temperature, under the technical concept of this invention, as long as the basic liquefaction requirements of the condenser 20 are met and the normal operation of the refrigeration cycle is ensured, air-cooling can also achieve rapid local cooling of the edge of the parting surface 5, thereby eliminating flash. The number and installation position of the fans 24 can be flexibly adjusted according to the specific structure and heat dissipation requirements of the condenser 20. For example, an axial flow fan can be used to blow air directly onto the condenser 20, or a suction method can be used to expel heat; both are within the scope of protection of this embodiment.

[0051] Example 8: As shown in Figures 9 and 10, this example is a further refinement of Example 2. Instead of heat exchange tubes 14, a heat exchange groove 13 is formed in the moving mold 1. The heat exchange groove 13 is a stepped groove, including a low-pressure groove 27 and a high-pressure groove 28. The low-pressure groove 27 and the high-pressure groove 28 are separated by a microporous plate 29, which has multiple micropores with a diameter less than 0.1 mm. A heat exchange plate 15 is installed on the low-pressure groove 27. Both the microporous plate 29 and the heat exchange plate 15 are fixed to the heat exchange groove 13 by welding. The high-pressure groove 28 is connected to the compressor 9, and the low-pressure groove 27 is connected to the gas-liquid separator 11. This eliminates the need for additional piping, allowing the refrigerant to directly contact the heat exchange plate 15, resulting in higher heat exchange efficiency and greater energy savings.

[0052] Example 9: As shown in Figure 11, this example is a further refinement of Example 2, mainly focusing on simplifying the heat exchange tube 14. The heat exchange tube 14 only includes a low-pressure tube 16 and a high-pressure tube 17. The low-pressure tube 16 and the high-pressure tube 17 are connected by multiple microporous tubes 18. No piston cylinder 19 is provided. The through holes of the microporous tubes 18 are laser-processed, with a diameter less than 0.08 mm. The high-pressure tube 17 is controlled to switch on and off with the compressor 9 via a second shut-off valve, and the low-pressure tube 16 is controlled to switch on and off with the gas-liquid separator 11 via a first shut-off valve. For smaller injection-molded parts 25, this design is simple and has a low cost.

[0053] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A heat exchange injection mold, characterized in that, The device includes a moving mold (1), a fixed mold (2), and a heat exchange device (3). A cavity (4) is formed between the fixed mold (2) and the moving mold (1). The parting surface (5) of the cavity (4) has a first contour line (6) on the moving mold (1), and the parting surface (5) of the cavity (4) has a second contour line (7) on the fixed mold (2). The heat exchange device (3) includes a compressor (9), a control valve (10), a gas-liquid separator (11), and a heat exchange channel (12). The heat exchange channel (12) is located near the first contour line. (6) or the second contour line (7) is provided, the compressor (9) is connected to the heat exchange channel (12), so that the compressor (9) can deliver high pressure liquid refrigerant to the heat exchange channel (12), the heat exchange channel (12) is provided with the control valve (10), so that when the control valve (10) is opened, the liquid refrigerant in the heat exchange channel (12) evaporates rapidly and enters the gas-liquid separator (11), the gas-liquid separator (11) is connected to the compressor (9) to provide gaseous refrigerant to the compressor (9).

2. The heat exchange injection mold according to claim 1, characterized in that, The fixed mold (2) is provided with an injection port (8), and the heat exchange channel (12) of the heat exchange device (3) is provided in the moving mold (1).

3. The heat exchange injection mold according to claim 2, characterized in that, The moving mold (1) is provided with a heat exchange groove (13), and a heat exchange tube (14) is provided in the heat exchange groove (13). The heat exchange groove (13) is arranged around the first contour line (6) or along the first contour line (6). The heat exchange groove (13) is covered with a heat exchange plate (15) made of a high thermal conductivity material.

4. The heat exchange injection mold according to claim 3, characterized in that, The heat exchange tube (14) includes a low-pressure tube (16) and a high-pressure tube (17). The low-pressure tube (16) and the high-pressure tube (17) are connected by a plurality of microporous tubes (18). The high-pressure tube (17) is connected to a piston cylinder (19), so that the pressure of the high-pressure tube (17) can be changed by the spatial change of the piston cylinder (19).

5. The heat exchange injection mold according to any one of claims 1 to 4, characterized in that, The heat exchange device (3) is equipped with a condenser (20) and a liquid receiver (21). The compressor (9) is connected to the condenser (20), the condenser (20) is connected to the liquid receiver (21), and the liquid receiver (21) is connected to the heat exchange channel (12).

6. The heat exchange injection mold according to claim 5, characterized in that, The condenser (20) is provided with a cold water tank (22) so that the condenser (20) is cooled by water cooling. The first end of the cold water tank (22) is connected to a water source, and the second end of the cold water tank (22) is connected to the water cooling channel (23) of the moving mold (1) or the fixed mold (2).

7. The heat exchange injection mold according to claim 5, characterized in that, The condenser (20) is cooled by a fan (24).

8. A heat exchange injection molding method, characterized in that, At least the following steps are included: S1, After the injection mold is closed, before or when the injection machine starts injection, the evaporation of the refrigerant in the heat exchange channel (12) of the heat exchange device (3) removes the heat from the edge of the parting surface (5) of the mold cavity (4), causing the temperature of the edge of the parting surface (5) of the mold cavity (4) to drop rapidly; S2, the injection machine completes the filling of the cavity (4) of the injection mold, the water cooling channel (23) is opened, the injection molded part (25) begins to cool and solidify, and after the pressure holding of the cavity (4) is completed, the refrigerant in the heat exchange channel (12) is controlled to stop evaporation by the control valve (10); S3, after solidification is completed, the mold is opened to eject the injection molded part (25), and the mold is closed.

9. The heat exchange injection molding method according to claim 8, characterized in that, The water in the water-cooling channel (23) first cools the condenser (20) of the heat exchange device (3), and then is transported to the moving mold (1) or the fixed mold (2) to cool the injection molded part (25).

10. An injection molded part, characterized in that, Manufactured using the heat exchange injection mold as described in any one of claims 1 to 4 or the heat exchange injection molding method as described in claim 8 or 9.

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