Injection molding exhaust system and mold

Abstract

The utility model relates to the technical field of exhaust of injection molds, in particular to an injection exhaust system and a mold, the injection exhaust system comprises an exhaust cavity and an exhaust assembly, and a first exhaust channel and a second exhaust channel are formed in the exhaust assembly. The two ends of the first exhaust channel and the two ends of the second exhaust channel communicate with the outside and the top of the cavity correspondingly, and the exhaust assembly is slidably connected into the exhaust cavity so that the first exhaust channel can be opened or closed. The exhaust assembly can adjust the sliding position in a self-adaptive mode according to the exhaust requirement in the mold filling process, the exhaust effect is good, and melt forming is not interfered.

Description

Technical Field

[0001] The utility model relates to the technical field of injection mold exhaust, and more specifically, to an injection molding exhaust system and a mold. Background Art

[0002] During the injection molding process of traditional PVC-U pipe injection molds, large amounts of gas often accumulate within the mold cavity as the molten material rapidly fills the mold cavity under high pressure. These gases primarily originate from the evaporation of moisture from the raw materials, gases generated by the decomposition of the raw materials, and residual air within the mold cavity. If these gases are not promptly and effectively expelled, a series of problems will arise. Gas accumulation hinders the smooth flow of the molten material, making it difficult to fill the mold, thereby reducing the filling speed of the molten material. This not only prolongs the injection molding cycle and increases production costs, but also may cause internal stress concentration in the pipe due to uneven molten material flow, affecting the pipe's mechanical properties and service life.

[0003] The Chinese patent of prior art CN201911004238.0 discloses a plastic injection mold, which relates to the field of injection molding technology, including a rear mold frame base plate, wherein the rear mold frame on the rear mold frame base plate is detachably connected to the front mold frame on the front mold frame base plate, and the rear mold core formed on the upper part of the rear mold frame and the front mold core formed on the lower part of the front mold frame constitute a cavity for mold injection, and the exhaust component includes a tube cavity, one end of the tube cavity is connected to the cavity, and the other end of the tube cavity extends upward from the top surface of the front mold frame base plate, and a matching exhaust pipe is provided in the tube cavity, one end of the exhaust pipe is connected to the cavity and is provided with a breathable microporous ring. This application exhausts the excess air in the cavity in time, thereby avoiding the generation of pores during the injection molding process, thereby improving the injection molding effect of the mold; and can use the activated carbon adsorption plate to adsorb harmful molecules contained in the hot-melt plastic raw materials, thereby ensuring exhaust while also being beneficial to the health of the staff, but the exhaust device is a fixed structure and cannot be adaptively adjusted according to the exhaust demand during the filling process. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiency of the exhaust device in the prior art that it cannot be adaptively adjusted according to the exhaust demand during the filling process, and to propose an injection molding exhaust system and a mold. The exhaust system can be adaptively adjusted according to the exhaust demand during the filling process, and the exhaust effect is good.

[0005] In order to achieve the above-mentioned purpose, an injection molding exhaust system is provided, including an exhaust cavity and an exhaust component, wherein a first exhaust channel and a second exhaust channel are formed in the exhaust component, and the two ends of the first exhaust channel and the second exhaust channel are respectively connected to the outside world and the top of the cavity, and the exhaust component is slidably connected in the exhaust cavity to open or close the first exhaust channel.

[0006] In the present technical solution, exhaust is divided into two stages. In the first stage, high-pressure molten material begins to fill the mold, and more trapped air is generated, and the exhaust demand is large. The exhaust component is in the initial position, which is that the exhaust component slides downward due to gravity and is suspended in the mold cavity. At this time, the first exhaust channel and the second exhaust channel are opened, and the trapped air can be discharged through the first exhaust channel and the second exhaust channel at the same time, thereby improving the exhaust efficiency and allowing the molten material to fill the mold smoothly. In the second stage, the filling is about to end, and the exhaust demand is small. As the melt liquid level gradually rises, the air pressure of the residual trapped air pushes the exhaust component to slide upward so that the molten material can fill the entire mold cavity. At this time, the first exhaust channel is closed, and the residual trapped air is discharged through the second exhaust channel. The exhaust component can adaptively slide and adjust according to the filling process to open or close the first exhaust channel, with good exhaust effect and without interfering with the filling of the molten material.

[0007] Preferably, the exhaust assembly includes a support block, a movable block, an exhaust pipe and a limit block, the support block is fixed in the exhaust cavity, the support block is provided with a first through hole for the exhaust pipe to pass through, the exhaust pipe is slidably connected to the first through hole, the gap between the exhaust pipe and the inner wall of the first through hole forms the first exhaust channel, one end of the exhaust pipe passes through the top of the support block and is connected to the limit block, the limit block is stuck in one end of the first through hole, the other end of the exhaust pipe passes through the bottom of the support block and is connected to the movable block, a second through hole is provided in the movable block that is connected to the exhaust pipe, and the exhaust pipe and the second through hole form the second exhaust channel. In the first stage, the movable block is driven by gravity to slide the exhaust pipe downward until the limit block abuts the top of the support block. At this time, the first exhaust channel and the second exhaust channel are opened, and a large amount of trapped air is discharged through the first exhaust channel and the second exhaust channel. In the second stage, the exhaust demand decreases. As the melt liquid level rises, trapped air remains between the melt liquid level and the movable block. The trapped air pushes the movable block to drive the exhaust pipe to slide upward, so that the upper surface of the movable block abuts the lower surface of the support block. The first exhaust channel is closed, so that the molten material can fill the mold cavity, avoiding the movable block interfering with the molding of the molten material, and the trapped air is discharged through the second through hole and the exhaust pipe.

[0008] Preferably, in order to improve the exhaust efficiency, the exhaust pipe is provided with a plurality of equally spaced first exhaust holes along its length. In the first stage, the gas in the gap between the exhaust pipe and the first through hole can also enter the exhaust pipe through the first exhaust holes and be discharged, thereby improving the exhaust efficiency.

[0009] Preferably, in order to slide the movable block to the lowest point in the first stage, the exhaust system also includes a first return spring, one end of the first return spring is connected to the inner wall of the exhaust chamber, and the other end of the first return spring is connected to the side of the limit block away from the exhaust pipe so that the limit block is pressed against the end face of the support block, and the first return spring can push the limit block to slide downward until it is pressed against the upper surface of the support block, thereby driving the exhaust pipe and the movable block to slide downward to the lowest point, so that the first exhaust channel is opened into place, and in the second stage, the trapped air pushes the limit block to compress the first return spring so that the upper surface of the movable block is pressed against the lower surface of the support block, thereby closing the first exhaust channel.

[0010] Preferably, in order to increase the sealing performance when the first exhaust channel is closed, the movable block is a truncated cone structure with a diameter gradually decreasing from the bottom to the top, and the bottom of the support block forms a receiving groove adapted to the movable block structure.

[0011] Preferably, in order to prevent the movable block from being subjected to the tension of the first return spring after filling and squeezing the unsolidified molten material, the side wall of the accommodating groove is provided with an accommodating cavity, and a positioning component is provided in the accommodating cavity, and one end of the positioning component extends out and clamps the movable block.

[0012] Preferably, the positioning assembly includes a second return spring, a positioning pin, a pull rod and a pull ring, the positioning pin is slidably connected in the accommodating cavity, one end of the second return spring is connected to the inner wall of the accommodating cavity, the other end of the second return spring is connected to one end of the positioning pin, one side of the movable block is provided with a positioning hole adapted to the positioning pin, the sliding direction of the pull rod is parallel to the positioning pin, one end of the pull rod is coaxially connected to the positioning pin, the other end of the pull rod passes through the support block and is connected to the pull ring, the sliding direction of the pull rod is parallel to the positioning pin, and one end of the pull rod is coaxially connected to the positioning pin. The end extends into the accommodating cavity and is connected to the positioning pin near one end of the second return spring, and the other end of the pull rod is connected to the pull ring. When the movable block slides upward into place and the positioning hole is aligned with the accommodating groove, the positioning pin is inserted into the positioning hole under the push of the second return spring to fix the movable block. When the movable block needs to be reset to the initial state, the pull ring is pulled outward, and the pull rod drives the positioning pin to retract to disengage from the positioning hole, and the movable block is released from the fixed state. Under the action of the first return spring, the movable block slides downward to the lowest point, and then the pull ring is released. The positioning pin extends out under the action of the second return spring to complete the reset.

[0013] In order to achieve the above-mentioned purpose, an injection mold is provided, including the above-mentioned injection molding exhaust system, and also including an upper mold, a lower mold, a gate sleeve and a core pulling assembly, the upper mold and the lower mold are interlocked and a cavity is formed between the upper mold and the lower mold, the gate sleeve is fixed to the top of the upper mold, the upper mold is provided with a runner whose two ends are respectively connected to the gate sleeve and the cavity, the core pulling assembly is arranged on one side of the lower mold and one end of the core pulling assembly is slidably connected to the cavity, one end of the exhaust cavity is connected to the outer wall of the upper mold, and the other end of the exhaust cavity is connected to the cavity.

[0014] In this technical solution, when the mold is closed, the upper mold and the lower mold are buckled together to form a cavity, and the molten material is quickly filled into the cavity from the gate sleeve on the top of the upper mold. The high-pressure gas and residual trapped air are discharged through the exhaust component, so that the molten material can be filled into the mold smoothly. After the molten material solidifies and cools, the mold is opened, the core pulling component performs the core pulling action, the upper mold and the lower mold are separated, and the injection molded part can be removed.

[0015] Preferably, in order to realize the core pulling action to complete demolding, the core pulling assembly includes a support frame, a telescopic structure, a sealing block and a movable core. The support frame is fixed to one side of the lower mold, one end of the telescopic structure is connected to the support frame, the telescopic end of the telescopic structure, the sealing block and the movable core are connected in sequence, and the movable core is arranged in the mold cavity.

[0016] Preferably, the mold cavity is adapted to the structure of the U-shaped tube, and the two ends of the mold cavity are respectively connected to the outer side walls of the upper mold and the lower mold, and the movable core is suspended in the mold cavity. One side of the sealing block abuts against the outer side walls of the upper mold and the lower mold to seal the mold cavity. After the mold is closed, a gap is left between the movable core and the upper mold cavity and the lower mold cavity to form the tube wall, and the movable core can shape the hollow structure of the U-shaped tube.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. The exhaust system of the utility model timely discharges a large amount of trapped air generated in the early stage of filling through the first exhaust channel and the second exhaust channel, and discharges the residual trapped air through the second exhaust channel in the later stage of filling. The exhaust effect is good and can ensure smooth filling of the melt.

[0019] 2. The exhaust component slides adaptively with the filling process, so that an exhaust channel can be opened and closed at different filling stages. This can adapt to different exhaust requirements during the filling process and prevent the exhaust component from interfering with the melt molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the injection molding exhaust system of the utility model;

[0021] Figure 2is a schematic diagram of a state where the first exhaust channel is closed;

[0022] Figure 3 is a schematic diagram of a state where the first exhaust channel is opened;

[0023] Figure 4 is a structural diagram of Example 2;

[0024] Figure 5 It is a structural diagram of the limit block;

[0025] Figure 6 It is a structural diagram of the injection mold of the utility model;

[0026] Figure 7 It is a structural diagram of the core pulling component.

[0027] In the figure: exhaust cavity 1; exhaust assembly 2; support block 21; first through hole 211; accommodating groove 212; accommodating cavity 2121; movable block 22; second through hole 221; positioning hole 222; exhaust pipe 23; first exhaust hole 231; limit block 24; first return spring 25; first exhaust channel 26; second exhaust channel 27; positioning assembly 3; second return spring 31; positioning pin 32; pull rod 33; pull ring 34; upper mold 4; runner 41; second exhaust hole 42; first positioning portion 43; lower mold 5; second positioning portion 51; gate sleeve 6; core pulling assembly 7; support frame 71; telescopic structure 72; sealing block 73; movable core 74; cavity 8. DETAILED DESCRIPTION

[0028] The drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate the embodiments, some components in the drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will understand that some well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0029] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0030] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0031] Example 1:

[0032] This embodiment is the first embodiment of the injection molding exhaust system. Figure 1 、 3 As shown in 4, it includes an exhaust cavity 1 and an exhaust component 2, a first exhaust channel 26 and a second exhaust channel 27 are formed in the exhaust component 2, the two ends of the first exhaust channel 26 and the second exhaust channel 27 are connected to the outside and the top of the cavity 8 respectively, and the exhaust component 2 is slidably connected in the exhaust cavity 1 to open or close the first exhaust channel 26.

[0033] In this embodiment, the first exhaust channel 26 and the second exhaust channel 27 can meet the discharge requirements of a large amount of gas in the initial stage of injection molding. The exhaust cavity 1 is arranged at the top of the cavity 8 to prevent the molten material from flowing out of the exhaust cavity 1.

[0034] Specifically, the exhaust assembly 2 includes a support block 21, a movable block 22, an exhaust pipe 23 and a limit block 24. The support block 21 is fixed in the exhaust chamber 1. The support block 21 is provided with a first through hole 211 for the exhaust pipe 23 to pass through. The exhaust pipe 23 is slidably connected to the first through hole 211. The gap between the exhaust pipe 23 and the inner wall of the first through hole 211 forms a first exhaust channel 26. One end of the exhaust pipe 23 passes through the top of the support block 21 and is connected to the limit block 24. The limit block 24 is stuck at one end of the first through hole 211. The other end of the exhaust pipe 23 passes through the bottom of the support block 21 and is connected to the movable block 22. A second through hole 221 communicating with the exhaust pipe 23 is provided in the movable block 22. The exhaust pipe 23 and the second through hole 221 form a second exhaust channel 27.

[0035] In this embodiment, the exhaust is divided into two stages. The first stage corresponds to the initial stage of injection molding, in which a large amount of trapped air is generated in the cavity 8. The second stage corresponds to the final stage of injection molding, in which trapped air remains in the cavity 8. When in the first stage, the state of the exhaust component 2 is as follows: Figure 3 As shown, the movable block 22 slides to the lowest point, and the limit block 24 abuts against the upper end surface of the support block 21, as shown in FIG. Figure 5 As shown, the limit block 24 can be a hollow circular structure to keep the first through hole 211 unobstructed, and the diameter of the circular structure is larger than the diameter of the first through hole 211. When in the second stage, the state of the exhaust component 2 is as follows Figure 2 As shown, the molten material pushes the movable block 22 to slide upward so that the upper end surface of the movable block 22 abuts against the lower end surface of the support block 21, thereby sealing the first exhaust channel 26, wherein the lower surface of the movable block 22 is an arc-shaped surface adapted to the outer surface structure. At this time, as the liquid level of the molten material rises, the residual trapped air is squeezed out through the second exhaust channel 27.

[0036] Specifically, the exhaust system also includes a first return spring 25, one end of the first return spring 25 is connected to the inner wall of the exhaust chamber 1, and the other end of the first return spring 25 is connected to the side of the limit block 24 away from the exhaust pipe 23 so that the limit block 24 is pressed against the end face of the support block 21.

[0037] In this embodiment, the first return spring 25 can assist the movable block 22 in sliding downward and returning to its original position after the injection molding is completed.

[0038] Specifically, the movable block 22 is a frustum structure with a diameter gradually decreasing from the bottom to the top, and the bottom of the support block 21 forms a receiving groove 212 adapted to the structure of the movable block 22 .

[0039] In this embodiment, the cooperation between the truncated cone structure and the capacitance groove 212 can enhance the sealing performance of the first exhaust channel 26 after it is closed, thereby preventing the melt from leaking out.

[0040] Specifically, a side wall surface of the accommodating groove 212 is provided with an accommodating cavity 2121 , and a positioning component 3 is provided in the accommodating cavity 2121 . One end of the positioning component 3 extends out and clamps the movable block 22 .

[0041] In this embodiment, the positioning assembly 3 can fix the movable block 22 after the molten material fills the cavity 8 , thereby preventing the movable block 22 from squeezing the unsolidified molten material under the action of the first return spring 25 .

[0042] Specifically, the positioning assembly 3 includes a second return spring 31, a positioning pin 32, a pull rod 33 and a pull ring 34. The positioning pin 32 is slidably connected in the accommodating chamber 2121. One end of the second return spring 31 is connected to the inner wall of the accommodating chamber 2121. The other end of the second return spring 31 is connected to one end of the positioning pin 32. A positioning hole 222 is provided on one side of the movable block 22 to match the positioning pin 32. The other end of the positioning pin 32 is inserted into the positioning hole 222. The pull rod 33 is parallel to the sliding direction of the positioning pin 32. One end of the pull rod 33 extends into the accommodating chamber 2121 and is connected to the end of the positioning pin 32 close to the second return spring 31. The other end of the pull rod 33 is connected to the pull ring 34.

[0043] In this embodiment, when the pull ring 34 is pulled, the pull rod 33 drives the positioning pin 32 to compress the second return spring 31 , so that the positioning pin 32 retracts into the accommodating cavity 2121 , and the movable block 22 can move freely.

[0044] The working principle of the injection molding exhaust system of this embodiment is as follows:

[0045] In the first stage, the movable block 22 slides out of the accommodating groove 212 under the action of the first return spring 25, and the positioning pin 32 extends out of the accommodating cavity 2121 under the action of the second return spring 31. The air between the exhaust pipe 23 and the support block 21 can meet the release of a large amount of trapped air;

[0046] In the second stage, as the molten material continues to fill the mold, the liquid level of the molten material continues to rise, thereby pushing the movable block 22 to overcome the tension of the first return spring 25 and slide upward. When the positioning hole 222 is aligned with the positioning pin 32, the positioning pin 32 is inserted into the positioning hole 222 under the action of the second return spring 25. At this time, the upper end face of the movable block 22 and the lower end face of the support block 21 abut to close the first exhaust channel 26, and the second exhaust channel 27 is always open to ensure that the residual trapped air can be discharged smoothly, and after the movable block 22 slides up, the molten material can fill the entire mold cavity 8 to avoid interference.

[0047] After injection molding, the pull ring 34 is pulled outward to make the positioning pin 32 disengage from the positioning hole 222, and the movable block 22 is reset under the action of the first reset spring 25. After the pull ring 34 is released, the positioning pin 32 is reset under the action of the second reset spring 31.

[0048] Example 2:

[0049] This embodiment is similar to embodiment 1, except that, in this embodiment, Figure 4 As shown, the exhaust pipe 23 is provided with a plurality of first exhaust holes 231 at equal intervals along its length.

[0050] In this embodiment, in the first stage, trapped air in the first exhaust channel 26 may flow into the exhaust pipe 23 through the first exhaust hole 231 and be discharged from the top of the exhaust pipe 23 , thereby improving the exhaust efficiency of the first exhaust channel 26 .

[0051] Example 3:

[0052] This embodiment is the first embodiment of the injection mold. Figure 6 、 7 As shown, it includes the above-mentioned injection molding exhaust system, and also includes an upper mold 4, a lower mold 5, a gate sleeve 6 and a core pulling assembly 7. The upper mold 4 and the lower mold 5 are buckled together and a cavity 8 is formed between the upper mold 4 and the lower mold 5. The gate sleeve 6 is fixed to the top of the upper mold 4. The upper mold 4 is provided with a runner 41 whose two ends are respectively connected to the gate sleeve 6 and the cavity 8. The core pulling assembly 7 is provided on one side of the lower mold 5 and one end of the core pulling assembly 7 is slidably connected to the cavity 8. The exhaust cavity 1 is provided in the upper mold 4, one end of the exhaust cavity 1 is connected to the outer wall of the upper mold 4, and the other end of the exhaust cavity 1 is connected to the cavity 8.

[0053] In this embodiment, if Figure 1As shown, two exhaust cavities 1 are respectively provided in the upper mold 4 and communicated with the top of the cavity 8. The two exhaust cavities 1 are respectively communicated with the outside through two second exhaust holes 422 provided on the upper mold 4. The second exhaust holes 422 are arranged perpendicular to the exhaust cavities 1, which can further prevent pollutants from entering the cavity 8. The two exhaust assemblies 2 are respectively provided in the two exhaust cavities 1. The two pull rods 33 extend into the exhaust cavities 1 from both sides of the upper mold 4. The bottom of the upper mold 4 is provided with a first positioning portion 43, as shown Figure 6 As shown, the top of the lower mold 5 is provided with a second positioning portion 51 that cooperates with the first positioning portion 43, wherein the first positioning portion 43 can be a raised cylinder and the second positioning portion 51 can be a countersunk hole. The cooperation between the first positioning portion 43 and the second positioning portion 51 can ensure the mold closing accuracy, thereby ensuring product quality.

[0054] Specifically, the core pulling assembly 7 includes a support frame 71, a telescopic structure 72, a sealing block 73 and a movable core 74. The support frame 71 is fixed to one side of the lower mold 5, and one end of the telescopic structure 72 is connected to the support frame 71. The telescopic end of the telescopic structure 72, the sealing block 73 and the movable core 74 are connected in sequence. The movable core 74 is arranged in the mold cavity 8. The mold cavity 8 is adapted to the structure of the U-shaped tube. The two ends of the mold cavity 8 are respectively connected to the outer walls of the upper mold 4 and the lower mold 5. The movable core 74 is suspended in the mold cavity 8. One side of the sealing block 73 abuts against the outer walls of the upper mold 4 and the lower mold 5 to seal the mold cavity 8.

[0055] In this embodiment, the telescopic structure 72 is an oil cylinder, and the movable core 74 is composed of six sections of tube cores, three of which are connected in series and connected to one end of the sealing block 73, and the other three sections are connected in series and connected to the other end of the sealing block 73. When the mold is closed, the end faces of the six sections of the tube core are connected in pairs to form the tube core of the U-shaped tube. When the mold is opened, the sealing block 73 slides out in parallel, driving the sections of the tube core on both sides to pull out the U-shaped tube, completing the demolding.

[0056] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are illustrative and cannot be understood as limitations on the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0057] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An injection molding exhaust system, characterized in that: The invention comprises an exhaust cavity (1) and an exhaust assembly (2), wherein a first exhaust channel (26) and a second exhaust channel (27) are formed in the exhaust assembly (2), and the two ends of the first exhaust channel (26) and the second exhaust channel (27) are respectively connected to the outside and the top of the cavity (8), and the exhaust assembly (2) is slidably connected in the exhaust cavity (1) to open or close the first exhaust channel (26).

2. An injection molding exhaust system according to claim 1, characterized in that: The exhaust assembly (2) comprises a support block (21), a movable block (22), an exhaust pipe (23) and a limit block (24); the support block (21) is fixed in the exhaust cavity (1); the support block (21) is provided with a first through hole (211) for the exhaust pipe (23) to pass through; the exhaust pipe (23) is slidably connected to the first through hole (211); a gap between the exhaust pipe (23) and the inner wall of the first through hole (211) forms the first exhaust channel (26); One end of the exhaust pipe (23) passes through the top of the support block (21) and is connected to the limit block (24); the limit block (24) is stuck in one end of the first through hole (211); the other end of the exhaust pipe (23) passes through the bottom of the support block (21) and is connected to the movable block (22); a second through hole (221) communicating with the exhaust pipe (23) is provided in the movable block (22); the exhaust pipe (23) and the second through hole (221) form the second exhaust channel (27).

3. An injection molding exhaust system according to claim 2, characterized in that: The exhaust pipe (23) is provided with a plurality of first exhaust holes (231) at equal intervals along its length direction.

4. An injection molding exhaust system according to claim 3, characterized in that: The exhaust system further comprises a first return spring (25), one end of the first return spring (25) being connected to the inner wall of the exhaust chamber (1), and the other end of the first return spring (25) being connected to a side of the limit block (24) facing away from the exhaust pipe (23) so that the limit block (24) is pressed against the end face of the support block (21).

5. The injection molding exhaust system according to claim 2, characterized in that: The movable block (22) is a truncated cone structure with a diameter gradually decreasing from the bottom to the top, and the bottom of the support block (21) forms a receiving groove (212) adapted to the structure of the movable block (22).

6. The injection molding exhaust system according to claim 5, characterized in that: The side wall of the accommodating groove (212) is provided with an accommodating cavity (2121), a positioning component (3) is provided in the accommodating cavity (2121), and one end of the positioning component (3) extends out and clamps the movable block (22).

7. The injection molding exhaust system according to claim 6, characterized in that: The positioning assembly (3) includes a second return spring (31), a positioning pin (32), a pull rod (33) and a pull ring (34); the positioning pin (32) is slidably connected in the accommodating cavity (2121); one end of the second return spring (31) is connected to the inner wall of the accommodating cavity (2121); the other end of the second return spring (31) is connected to one end of the positioning pin (32); one side of the movable block (22) is provided with a positioning hole (222) adapted to the positioning pin (32); the sliding direction of the pull rod (33) is parallel to that of the positioning pin (32); one end of the pull rod (33) is coaxially connected to the positioning pin (32); the other end of the pull rod (33) passes through the support block (21) and is connected to the pull ring (34).

8. An injection mold, characterized in that: An injection molding exhaust system comprising any one of claims 1 to 7, further comprising an upper mold (4), a lower mold (5), a sprue sleeve (6) and a core pulling assembly (7), wherein the upper mold (4) and the lower mold (5) are interlocked and a cavity (8) is formed between the upper mold (4) and the lower mold (5), the sprue sleeve (6) is fixed to the top of the upper mold (4), the upper mold (4) is provided with a runner (41) whose two ends are respectively connected to the sprue sleeve (6) and the cavity (8), the core pulling assembly (7) is provided on one side of the lower mold (5) and one end of the core pulling assembly (7) is slidably connected to the cavity (8), the exhaust cavity (1) is provided in the upper mold (4), one end of the exhaust cavity (1) is connected to the outer wall of the upper mold (4), and the other end of the exhaust cavity (1) is connected to the cavity (8).

9. The injection mold according to claim 8, characterized in that: The core pulling assembly (7) includes a support frame (71), a telescopic structure (72), a sealing block (73) and a movable core (74); the support frame (71) is fixed to one side of the lower mold (5); one end of the telescopic structure (72) is connected to the support frame (71); the telescopic end of the telescopic structure (72), the sealing block (73) and the movable core (74) are connected in sequence; and the movable core (74) is arranged in the mold cavity (8).

10. The injection mold according to claim 9, characterized in that: The mold cavity (8) is adapted to the structure of the U-shaped tube, and the two ends of the mold cavity (8) are respectively connected to the outer walls of the upper mold (4) and the lower mold (5), the movable core (74) is suspended in the mold cavity (8), and one side of the sealing block (73) abuts against the outer walls of the upper mold (4) and the lower mold (5) to seal the mold cavity (8).

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