A vacuum pumping method for a mold

Abstract

The present invention provides a vacuum pumping method for a mold, belonging to the technical field of molds. It solves the problem that the existing molds have poor vacuum pumping effect on the molded parts with multiple molding. In the vacuum pumping method of this mold, the mold includes a fixed mold, a hot nozzle sleeve arranged in the fixed mold, and a gate valve needle assembly partially inserted into the hot nozzle sleeve. The gate valve needle assembly includes a gate valve needle. This vacuum pumping method includes the following steps: Mold closing and assembly: The fixed mold and the moving mold are closed, and a cavity is formed after the fixed mold and the moving mold are closed. A support wall horizontally arranged and abutted against the fixed mold is formed on the hot nozzle sleeve, so that there is a ventilation gap between the outer bottom wall of the hot nozzle sleeve and the fixed mold. An air extraction channel is formed by machining in the hot nozzle sleeve, and an exhaust channel communicated with the air outlet of the air extraction channel is formed by machining on the fixed mold. The seal on the support wall abuts against the fixed mold and is located outside the ventilation gap. The vacuum pumping method of this mold improves the vacuum pumping effect on the molded parts with multiple molding.

Description

Technical Field

[0001] The present invention belongs to the technical field of molds and relates to a vacuum pumping method for molds. Background Art

[0002] During the injection molding process of a mold, there must be a certain amount of gas in the cavity after the mold is closed. During the injection process, the air in the cavity can be discharged from the exhaust groove or exhaust hole. However, for rapidly injected or molded parts that require multiple injections, the cooled injection raw material will block the original exhaust groove and exhaust hole. If the air in the cavity during secondary molding is not completely discharged, it will cause phenomena such as pores and bubbles in the molded part, thereby affecting the qualification rate of the molded part.

[0003] In view of the above problems, various vacuum pumping methods for molds have been developed: For example, Chinese Patent Application [Authorized Publication No.: CN211251199U] discloses an in-mold vacuum pumping device for an injection mold for multi-cavity thin-walled plastic parts, including an upper mold and a lower mold. An upper mold core is provided on the upper mold, and a lower mold core is provided on the lower mold. After the upper mold and the lower mold are closed, the upper mold core and the lower mold core form a cavity for molding a workpiece. The cavity is also connected to a gas suction device for sucking out the trapped air inside the cavity. An injection port is also provided on the upper mold, and the injection port is communicated with the cavity. The gas suction device includes an air flow channel provided in the upper mold and / or the lower mold, and an exhaust groove provided in the corresponding parting surface part of the upper mold and / or the lower mold. The input end of the exhaust groove is communicated with the output end of the air flow channel, and the output end of the exhaust groove is communicated with the cavity, and a vacuum pumping device is connected to the input end of the air flow channel.

[0004] The above structure requires an air flow channel to be provided in the upper mold and / or the lower mold, and an exhaust groove to be provided on the parting surface. The air flow channel is communicated with the vacuum pumping device through the exhaust groove, thereby realizing the vacuum pumping of the cavity. However, for some molded parts such as two-color plastic parts that require two injections, during the first injection, the air in the cavity can be discharged through the air flow channel and the exhaust groove. However, during the second injection, the cooled and molded plastic part is likely to block the input end of the air flow channel, thereby making it impossible to realize the secondary vacuum pumping of the cavity, resulting in a poor vacuum pumping effect of the mold and affecting the molding quality of the molded part. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems existing in the prior art and propose a vacuum pumping method for molds. The technical problem to be solved by the present invention is: how to solve the problem of poor vacuum pumping effect of existing molds for molded parts that require multiple moldings.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A vacuum pumping method for a mold, the mold comprising a fixed mold, a hot nozzle sleeve disposed within the fixed mold, and a gate valve needle assembly partially inserted into the hot nozzle sleeve. The gate valve needle assembly includes a gate valve needle, and is characterized in that the vacuum pumping method comprises the following steps:

[0008] A. Mold closing and assembly: The fixed mold and the moving mold are closed, and a cavity is formed after the fixed mold and the moving mold are closed. A support wall horizontally arranged and abutted against the fixed mold is formed on the hot nozzle sleeve, so that there is a ventilation gap between the outer bottom wall of the hot nozzle sleeve and the fixed mold. An air extraction channel is formed in the hot nozzle sleeve, and an exhaust channel communicated with the air outlet of the air extraction channel is formed in the fixed mold. The seal on the support wall abuts against the fixed mold and is located outside the ventilation gap;

[0009] B. Vacuum pumping: The driving member of the gate valve needle is opened, so that the gate valve needle moves towards the cavity and is partially inserted into the cavity, and an air passing gap is formed between the gate valve needle and the fixed mold. The vacuum pump connected to the exhaust channel is started, so that the air in the cavity is sequentially extracted from the mold through the air passing gap, the ventilation gap, the air extraction channel and the exhaust channel;

[0010] C. Injection molding: The driving member of the gate valve needle is opened, so that the gate valve needle moves away from the cavity and is located outside the cavity, and then the cavity is injected through the injection hot nozzle of the gate valve needle assembly.

[0011] Working principle: The existing vacuum pumping method is applicable to molds for multi-shot injection molding. Before step A, the fixed mold and the moving mold are closed. At this time, an annular cavity is formed after the fixed mold and the moving mold are closed. Before injection molding, the cavity is evacuated through the parting surface formed by closing the fixed mold and the moving mold. Then, the molten injection material is injected into the cavity by the injection nozzle for one-shot molding, realizing the injection molding of the one-shot molded plastic part. At this time, the one-shot molded plastic part blocks the parting surface, and a cavity is also formed between the fixed mold and the moving mold. And through the support wall formed by machining on the nozzle sleeve, the nozzle sleeve is supported and positioned in the fixed mold. Due to the setting of the support wall, an air vent gap is formed between the nozzle sleeve and the outer bottom wall and the fixed mold through which gas can pass while the molten injection material cannot pass. And by machining the air extraction channel and the exhaust channel, the driving part of the gate valve pin is opened, and the gate valve pin moves towards the cavity, making part of it penetrate into the cavity. At this time, an air passing gap is formed between the gate valve pin and the fixed mold. At the same time, the vacuum pump connected to the exhaust channel is started, so that the air in the cavity can be pumped out of the mold in sequence through the air passing gap, the air vent gap, the air extraction channel and the exhaust channel, thus realizing the rapid vacuum pumping of the two-shot molded plastic part. The above method is to machine a support wall on the nozzle sleeve, so that an air vent gap is formed between the outer bottom wall of the nozzle sleeve and the fixed mold, ensuring that the size of the air vent gap does not change when the nozzle sleeve and the fixed mold are assembled. The positioning between the nozzle sleeve and the fixed mold is through the support wall, and it does not need to be through the cooperation between the outer bottom wall of the nozzle sleeve and the fixed mold. Therefore, a relatively large air vent gap can be formed between the outer bottom wall of the nozzle sleeve and the fixed mold to realize the multiple vacuum pumping of the cavity, without the need to additionally set other components. And the overall volume of the nozzle sleeve is small, so it is more convenient to machine the nozzle sleeve alone, thus saving the transformation cost while realizing the multiple vacuum pumping of the cavity.

[0012] Since the function of the nozzle sleeve is to cool part of the gate valve pin assembly, by setting a seal, the nozzle sleeve can both evacuate the cavity and cool part of the gate valve pin assembly without affecting each other, thus further improving the stability of the vacuum pumping method.

[0013] In the above vacuum pumping method for the mold, in the step A, a first sealing surface is machined on the outer bottom wall of the nozzle sleeve, and a second sealing surface is machined on the fixed mold. The vertical cross-sections of the first sealing surface and the second sealing surface are both inclined outward from bottom to top. The first sealing surface and the second sealing surface are parallel, and the parallel distance between the first sealing surface and the second sealing surface is 0.02 mm to 0.04 mm. Part of the above air vent gap is formed between the first sealing surface and the second sealing surface.

[0014] By providing parallel sealing surfaces 1 and 2, the gas inhaled into the ventilation gap can be more uniform. The parallel distance between sealing surfaces 1 and 2 is set to ensure that while the ventilation is smooth, the molten injection molding raw material is prevented from entering the ventilation gap, thereby further improving the vacuum pumping efficiency of the mold while ensuring the stability of the vacuum pumping.

[0015] In the above-mentioned vacuum pumping method for the mold, in step B, the gate valve pin sequentially passes through sealing surfaces 1 and 2 and is partially disposed in the cavity, and the ventilation gap is 0.02 mm to 0.04 mm.

[0016] By setting the size of the ventilation gap, it is ensured that while the ventilation is smooth, the molten injection molding raw material is prevented from entering the ventilation gap, thus improving the vacuum pumping efficiency of the mold.

[0017] In the above-mentioned vacuum pumping method for the mold, in step A, a first buffer surface connected to sealing surface 1 is formed on the outer bottom wall of the hot nozzle sleeve, and a second buffer surface connected to sealing surface 2 is formed on the fixed mold. The vertical cross-sections of the first buffer surface and the second buffer surface are both inclined outward from bottom to top, and the angle between the vertical cross-section of the first buffer surface and the horizontal plane is greater than the angle between the vertical cross-section of the second buffer surface and the horizontal plane. A part of the above-mentioned ventilation gap is formed between the first buffer surface and the second buffer surface.

[0018] The provision of the first buffer surface and the second buffer surface enables the air in the cavity to be buffered between the first buffer surface and the second buffer surface after passing through the sealing surfaces 1 and 2, and can improve the smoothness of the vacuum pumping, thereby further increasing the vacuum pumping efficiency.

[0019] In the above-mentioned vacuum pumping method for the mold, in step A, a first relief surface that is flat and connected to the first buffer surface is formed on the outer bottom wall of the hot nozzle sleeve, and a second relief surface connected to the second buffer surface is formed on the fixed mold. The second relief surface is a concave arc surface facing away from the first relief surface. A relief space is formed between the first relief surface and the second relief surface, and the relief space is communicated with the ventilation gap.

[0020] The provision of the relief space enables the air in the cavity to quickly enter the relief space and be buffered therein, avoiding a large impact on the hot nozzle sleeve, thereby further increasing the vacuum pumping efficiency.

[0021] In the above-mentioned method for vacuuming the mold, in step A, the outer bottom wall of the hot nozzle sleeve is processed to form a guide surface 1, and the fixed mold is processed to form a guide surface 2 which is arranged parallel to the guide surface 1 and connected to the give way surface 2. The vertical cross-section of the guide surface 1 and the vertical cross-section of the guide surface 2 are both arranged to be inclined outward from bottom to top, and the guide surface 1 is arranged between the give way surface 1 and the support wall. Part of the above-mentioned ventilation gap is formed between the guide surface 1 and the guide surface 2 and is connected to the exhaust channel.

[0022] The guide surface one and the guide surface two are arranged in parallel, which can guide the air in the air gap, so that the air in the air gap can enter the exhaust channel quickly and in the shortest path, further improving the vacuum efficiency of the mold.

[0023] In the above-mentioned method of vacuuming the mold, in step A, the supporting wall is annular, the sealing member is an annular sealing ring 1, the air outlet of the ventilation gap and the air inlet of the exhaust channel are both located inside the sealing ring 1, and the air inlet of the exhaust channel is located on the side of the supporting wall close to the ventilation gap.

[0024] The shape setting of the supporting wall can better realize the positioning support of the hot nozzle sleeve, and the setting of the sealing ring can prevent the air entering the exhaust channel through the ventilation gap from flowing out from the gap between the supporting wall and the fixed mold, further improving the stability of vacuum extraction; the position setting of the air inlet of the exhaust channel can facilitate the connection between the air inlet of the exhaust channel and the ventilation gap, so that the air in the ventilation gap can be quickly introduced into the exhaust channel, further improving the vacuum extraction efficiency.

[0025] In the above-mentioned method of vacuuming the mold, in the above-mentioned step B, the outer wall of the hot nozzle sleeve is processed to have an annular cooling circulation channel, and the upper end of the outer wall of the hot nozzle sleeve is processed to have an outwardly protruding and annular limit stop edge, the cooling circulation channel is located below the limit stop edge, the bottom wall of the limit stop edge is horizontally arranged, and the sealing ring 2 on the bottom wall is abutted against the fixed mold, and the air outlet of the exhaust channel is located on the outer wall of the limit stop edge.

[0026] By setting the limit stop edge, the support of the entire hot nozzle sleeve is made more stable, ensuring the size of the ventilation gap, and the coordinated setting of the sealing ring 1 and the sealing ring 2 can further separate the exhaust channel from the cooling circulation channel, so that the vacuuming and cooling on the hot nozzle sleeve do not affect and interfere with each other, further improving the stability of vacuuming.

[0027] In the above-mentioned vacuum pumping method for the mold, in the step A, a vertically arranged air passage 1 and a horizontally arranged air passage 2 are formed by machining on the hot nozzle sleeve. The air passage 1 and the air passage 2 constitute the above-mentioned air extraction channel. The air passage 2 is communicated with the side wall of the upper end of the air passage 1. The air inlet of the air passage 1 is communicated with the ventilation gap, and the air outlet of the air passage 2 is communicated with the air inlet of the exhaust passage.

[0028] The air passage 1 is communicated with the side wall of the upper end of the air passage 2. At this time, there is a certain distance between the upper end surface of the air passage 2 and the air passage 1, which can facilitate the buffering of the air entering the air passage 2 on the air passage 1. At the same time, because the upper end of the air passage 1 does not need to be aligned with the air passage 2, it is more convenient during the machining of the hot nozzle sleeve. Thus, while the machining is more convenient, it can also play a buffering role, making the air extraction more stable.

[0029] In the above-mentioned vacuum pumping method for the mold, in the step A, an annular exhaust groove 1 that communicates the ventilation gap with the air passage 1 is formed by machining on the support wall. The outer side wall of the limit retaining edge is fitted with the fixed mold. An annular exhaust groove 2 is formed by machining on the outer side wall of the limit retaining edge. The exhaust groove 2 is communicated with the air outlet of the air passage 2.

[0030] The arrangement of the exhaust groove 1 and the exhaust groove 2 enables only one exhaust passage to be provided on the fixed mold. Thus, the modification to the fixed mold is smaller, facilitating the machining and transformation of the existing mold. At the same time, it can also enable the gas to be quickly extracted, improving the air extraction efficiency of the mold.

[0031] In the above-mentioned vacuum pumping method for the mold, in the step A, two annular sealing grooves are formed by machining on the outer side wall of the limit retaining edge. The air passage 2 is arranged between the two sealing grooves. An O-ring is arranged in the sealing groove and the O-ring abuts against the fixed mold for sealing.

[0032] The arrangement of the O-ring enables the gas flowing out of the air passage 2 to directly flow into the exhaust passage and will not flow out from the gap between the limit retaining edge and the fixed mold. And by the way that the outer side wall of the O-ring fits with the fixed mold, the friction during the up and down movement of the hot nozzle sleeve is reduced, making the movement of the hot nozzle sleeve smoother.

[0033] Compared with the prior art, the vacuum pumping method for this mold has the following advantages:

[0034] 1. The above method is to process and form a support wall on the nozzle sleeve, so that there is a ventilation gap between the outer bottom wall of the nozzle sleeve and the fixed mold, ensuring that the size of the ventilation gap remains unchanged when the nozzle sleeve and the fixed mold are assembled. The positioning between the nozzle sleeve and the fixed mold is achieved through the support wall, without the need for the cooperation between the outer bottom wall of the nozzle sleeve and the fixed mold. Therefore, a relatively large ventilation gap can be formed between the outer bottom wall of the nozzle sleeve and the fixed mold to achieve multiple vacuum extractions of the cavity, without the need to additionally set other components. Moreover, the overall volume of the nozzle sleeve is small, so it is more convenient to process the nozzle sleeve alone, thus saving the transformation cost while also achieving multiple vacuum extractions of the cavity.

[0035] 2. By providing parallel sealing surface 1 and sealing surface 2, the gas can be inhaled into the ventilation gap more evenly. The setting of the parallel distance between sealing surface 1 and sealing surface 2 enables the ventilation gap to ensure smooth air extraction while preventing the molten injection molding raw material from entering the ventilation gap, thereby further improving the vacuum extraction efficiency of the mold while ensuring the stability of air extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a cross-sectional view of the gate valve pin penetrating into the cavity in the present invention.

[0037] Figure 2 It is Figure 1 The partial enlarged view of part A in

[0038] Figure 3 It is Figure 2 The partial enlarged view of part C in

[0039] Figure 4 It is Figure 1 The partial enlarged view of part B in

[0040] Figure 5 It is the structural schematic diagram of the nozzle sleeve in the present invention.

[0041] In the figure, 1. Fixed mold; 11. Exhaust channel; 12. Sealing surface 2; 13. Guide surface 2; 14. Relief surface 2; 15. Buffer surface 2; 2. Movable mold; 3. Cavity; 4. Nozzle sleeve; 41. Air extraction channel; 41a. Airway 1; 41b. Airway 2; 42. Support wall; 42a. Sealing element; 42b. Exhaust groove 1; 43. Limit retaining edge; 43a. Sealing ring 2; 43b. Sealing groove; 43c. Exhaust groove 2; 44. O-ring; 45. Cooling water circulation channel; 46. Sealing surface 1; 47. Guide surface 1; 48. Relief surface 1; 49. Buffer surface 1; 5. Gate valve pin assembly; 51. Gate valve pin; 52. Nozzle base; 6. Ventilation gap; 8. Relief space; 9. Air passage gap. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following are specific embodiments of the present invention, in combination with the accompanying drawings, to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0043] As Figure 1 and Figure 4 shown, the vacuum pumping method of this mold, the mold includes a fixed mold 1, a movable mold 2, a hot nozzle sleeve 4 arranged in the fixed mold 1, and a gate valve needle assembly 5 partially inserted into the hot nozzle sleeve 4.

[0044] Specifically, as Figures 1-5 shown, the vacuum pumping method includes the following steps:

[0045] Before step A, the fixed mold 1 and the movable mold 2 are closed. At this time, after the fixed mold 1 and the movable mold 2 are closed, a ring-shaped cavity 3 is formed. Before injection molding, the cavity 3 is evacuated through the parting surface formed by the closing of the fixed mold 1 and the movable mold 2. Then, the molten injection raw material is injected into the cavity 3 by the injection nozzle for one-time molding, realizing the injection molding of the plastic part for one-time molding. At this time, the plastic part for one-time molding blocks the parting surface.

[0046] A. Clamping and assembling: The fixed mold 1 and the movable mold 2 are closed, and a cavity 3 is formed after the fixed mold 1 and the movable mold 2 are closed. A support wall 42 horizontally arranged and abutted against the fixed mold 1 is formed on the hot nozzle sleeve 4, so that there is a ventilation gap 6 between the outer bottom wall of the hot nozzle sleeve 4 and the fixed mold 1. An air extraction channel 41 is formed in the hot nozzle sleeve 4, and an exhaust channel 11 communicated with the air outlet of the air extraction channel 41 is formed on the fixed mold 1. The seal 42a on the support wall 42 abuts against the fixed mold 1 and is located outside the ventilation gap 6. A first sealing surface 46 is formed on the outer bottom wall of the hot nozzle sleeve 4, and a second sealing surface 12 is formed on the fixed mold 1. The vertical cross-sections of the first sealing surface 46 and the second sealing surface 12 are both inclined outward from bottom to top. The first sealing surface 46 and the second sealing surface 12 are parallelly arranged, and the parallel distance between the first sealing surface 46 and the second sealing surface 12 is 0.02 mm to 0.04 mm. A part of the above-mentioned ventilation gap 6 is formed between the first sealing surface 46 and the second sealing surface 12;

[0047] B. Vacuum pumping: The driving member of the gate valve needle 51 is opened, so that the gate valve needle 51 moves towards the cavity 3 and is partially inserted into the cavity 3, and an air passing gap 9 is formed between the gate valve needle 51 and the fixed mold 1. The gate valve needle 51 sequentially passes through the first sealing surface 46 and the second sealing surface 12 and is partially arranged in the cavity 3. The air passing gap 9 is 0.02 mm to 0.04 mm. The vacuum pump connected to the exhaust channel 11 is started, so that the air in the cavity 3 is sequentially extracted from the mold through the air passing gap 9, the ventilation gap 6, the air extraction channel 41 and the exhaust channel 11;

[0048] C. Injection molding: Activate the driving part of the gate valve pin 51 to move the gate valve pin 51 away from the cavity 3 and position it outside the cavity 3, and then inject the molten plastic into the cavity 3 through the injection nozzle of the gate valve pin assembly 5.

[0049] Working principle: The existing vacuum pumping method is applicable to molds for multiple injections. Before step A, the fixed mold 1 and the moving mold 2 are clamped. At this time, a ring-shaped cavity 3 is formed after the fixed mold 1 and the moving mold 2 are clamped. Before injection molding, the cavity 3 is evacuated through the parting surface formed by the clamping of the fixed mold 1 and the moving mold 2. Then, the molten injection material is injected into the cavity 3 by the injection nozzle for one-time molding, realizing the injection molding of the plastic part for one-time molding. At this time, the plastic part for one-time molding blocks the parting surface, and a cavity 3 is also formed between the fixed mold 1 and the moving mold 2. And through the support wall 42 formed by machining on the nozzle sleeve 4, the nozzle sleeve 4 is supported and positioned in the fixed mold 1. Due to the setting of the support wall 42, there is a ventilation gap 6 between the outer bottom wall of the nozzle sleeve 4 and the fixed mold 1 that allows gas to pass through while the molten injection material cannot pass through. By setting parallel sealing surfaces 46 and 12, the gas can be inhaled into the ventilation gap 6 more evenly. The setting of the parallel distance between the sealing surface 46 and the sealing surface 12 is used to ensure that the ventilation gap 6 can avoid the molten injection material from entering the ventilation gap 6 while ensuring smooth air extraction. And through the machining of the air extraction channel 41 and the exhaust channel 11, activate the driving part of the gate valve pin 51 to move the gate valve pin 51 towards the cavity 3, so that part of it penetrates into the cavity 3. At this time, an air passing gap 9 is formed between the gate valve pin 51 and the fixed mold 1. At the same time, start the vacuum pump connected to the exhaust channel 11, so that the air in the cavity 3 can be pumped out of the mold successively through the air passing gap 9, the ventilation gap 6, the air extraction channel 41 and the exhaust channel 11, thus realizing the rapid vacuum pumping of the plastic part for secondary molding. The above method is to machine the support wall 42 on the nozzle sleeve 4, so that there is a ventilation gap 6 between the outer bottom wall of the nozzle sleeve 4 and the fixed mold 1, ensuring that the size of the ventilation gap 6 is not changed when the nozzle sleeve 4 and the fixed mold 1 are assembled. The positioning between the nozzle sleeve 4 and the fixed mold 1 is through the support wall 42, and there is no need for the cooperation between the outer bottom wall of the nozzle sleeve 4 and the fixed mold 1. Therefore, a relatively large ventilation gap 6 can be formed between the outer bottom wall of the nozzle sleeve 4 and the fixed mold 1 to realize multiple vacuum pumping of the cavity 3 without the need to additionally set other components. And the overall volume of the nozzle sleeve 4 is small, so it is more convenient to machine the nozzle sleeve 4 alone, thus saving the transformation cost while also realizing multiple vacuum pumping of the cavity 3.

[0050] Such as Figures 2-4As shown, in step A, a first buffer surface 49, a first relief surface 48, and a first guiding surface 47 are successively formed on the outer bottom wall of the hot nozzle sleeve 4 from bottom to top. A second buffer surface 15, a second relief surface 14, and a second guiding surface 13 are successively formed on the fixed mold 1 from bottom to top. The vertical cross-sections of the first buffer surface 49 and the second buffer surface 15 are both inclined outward from bottom to top. The angle between the vertical cross-section of the first buffer surface 49 and the horizontal plane is greater than the angle between the vertical cross-section of the second buffer surface 15 and the horizontal plane. A part of the above-mentioned ventilation gap 6 is formed between the first buffer surface 49 and the second buffer surface 15. The first relief surface 48 is a horizontally arranged plane, and the second relief surface 14 is an arc surface that is recessed away from the first relief surface 48. A relief space 8 is formed between the first relief surface 48 and the second relief surface 14. The relief space 8 communicates with the ventilation gap 6. The first guiding surface 47 and the second guiding surface 13 are arranged in parallel, and the vertical cross-sections of the first guiding surface 47 and the second guiding surface 13 are both inclined outward from bottom to top. The first guiding surface 47 is arranged between the first relief surface 48 and the support wall 42. A part of the above-mentioned ventilation gap 6 is formed between the first guiding surface 47 and the second guiding surface 13 and communicates with the air extraction channel 41. The support wall 42 is annular, the seal 42a is a first annular sealing ring, and the air outlet of the ventilation gap 6 and the air inlet of the air extraction channel 41 are both located within the first sealing ring. The air inlet of the air extraction channel 41 is arranged on the side of the support wall 42 close to the ventilation gap 6.

[0051] As Figures 2-4 shown, in step B, a circular cooling circulation channel is formed on the outer side wall of the hot nozzle sleeve 4. The gate valve needle assembly 5 includes a hot nozzle base 52 fixedly connected to the fixed mold 1. An outwardly protruding annular limit retaining edge 43 is formed at the upper end of the outer side wall of the hot nozzle sleeve 4. The upper end of the limit retaining edge 43 abuts against the lower end of the hot nozzle base 52. The cooling circulation channel is located below the limit retaining edge 43. The bottom wall of the limit retaining edge 43 is horizontally arranged, and the second sealing ring 43a on the bottom wall abuts against the fixed mold 1. The air outlet of the air extraction channel 41 is located on the outer side wall of the limit retaining edge 43.

[0052] As Figure 4 and Figure 5 shown, in step A, a vertically arranged air passage 41a and a horizontally arranged air passage 41b are formed on the hot nozzle sleeve 4. The air passage 41b communicates with the side wall at the upper end of the air passage 41a. The air inlet of the air passage 41a communicates with the ventilation gap 6. The air outlet of the air passage 41b communicates with the air inlet of the exhaust passage 11. The diameter of the air outlet of the air passage 41b is smaller than the diameter of the air inlet of the exhaust passage 1111.

[0053] As Figures 2-5As shown, in step A, an exhaust groove 42b which is annular and communicates with the ventilation gap 6 is formed on the support wall 42. The exhaust groove 42b is located directly below the air passage 41a and communicates with the air passage 41a. The outer wall of the limit retaining edge 43 is attached to the fixed mold 1. An annular exhaust groove 43c is formed on the outer wall of the limit retaining edge 43. The exhaust groove 43c communicates with the air outlet of the air passage 41b. Two annular sealing grooves 43b are formed on the outer wall of the limit retaining edge 43. The air passage 41b is arranged between the two sealing grooves 43b. An O-ring 44 is arranged in the sealing groove 43b and the O-ring 44 abuts against the fixed mold 1 for sealing.

[0054] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A vacuum pumping method for a mold, the mold comprising a fixed mold (1), a hot nozzle sleeve (4) disposed within the fixed mold (1), and a gate valve needle assembly (5) partially inserted into the hot nozzle sleeve (4), the gate valve needle assembly (5) including a gate valve needle (51), characterized in that, The vacuum pumping method includes the following steps: A. Mold closing and assembling: The fixed mold (1) and the movable mold (2) are closed, and a cavity (3) is formed after the fixed mold (1) and the movable mold (2) are closed. A support wall (42) which is horizontally arranged and abuts against the fixed mold (1) is machined on the hot nozzle sleeve (4), so that there is a ventilation gap (6) between the outer bottom wall of the hot nozzle sleeve (4) and the fixed mold (1). An air extraction channel (41) is machined in the hot nozzle sleeve (4), and an exhaust channel (11) which is communicated with the air outlet of the air extraction channel (41) is machined on the fixed mold (1). The seal (42a) on the support wall (42) abuts against the fixed mold (1) and is located outside the ventilation gap (6); B. Vacuum pumping: The driving part of the gate valve pin (51) is opened, so that the gate valve pin (51) moves towards the cavity (3) and partially penetrates into the cavity (3), and an air passing gap (9) is formed between the gate valve pin (51) and the fixed mold (1). The vacuum pump connected to the exhaust channel (11) is started, so that the air in the cavity (3) is sequentially extracted from the mold through the air passing gap (9), the ventilation gap (6), the air extraction channel (41) and the exhaust channel (11); C. Injection molding: The driving part of the gate valve pin (51) is opened, so that the gate valve pin (51) moves away from the cavity (3) and is located outside the cavity (3), and then the cavity (3) is injected through the injection hot nozzle of the gate valve pin assembly (5).

2. The vacuum pumping method of the mold according to claim 1, characterized in that, In the step A, a first sealing surface (46) is machined on the outer bottom wall of the hot nozzle sleeve (4), and a second sealing surface (12) is machined on the fixed mold (1). The vertical sections of the first sealing surface (46) and the second sealing surface (12) are both inclined outwards from bottom to top. The first sealing surface (46) and the second sealing surface (12) are arranged in parallel, and the parallel distance between the first sealing surface (46) and the second sealing surface (12) is 0.02 mm to 0.04 mm. A part of the above ventilation gap (6) is formed between the first sealing surface (46) and the second sealing surface (12).

3. The vacuum pumping method for the mold according to claim 2, characterized in that In the step B, the gate valve pin (51) sequentially penetrates through the first sealing surface (46) and the second sealing surface (12) and is partially arranged in the cavity (3), and the air passing gap (9) is 0.02 mm to 0.04 mm.

4. The vacuum pumping method of the mold according to claim 3, wherein In the step A, a first buffer surface (49) connected to the first sealing surface (46) is machined on the outer bottom wall of the hot nozzle sleeve (4), and a second buffer surface (15) connected to the second sealing surface (12) is machined on the fixed mold (1). The vertical sections of the first buffer surface (49) and the second buffer surface (15) are both inclined outwards from bottom to top, and the included angle between the vertical section of the first buffer surface (49) and the horizontal plane is greater than the included angle between the vertical section of the second buffer surface (15) and the horizontal plane. A part of the above ventilation gap (6) is formed between the first buffer surface (49) and the second buffer surface (15).

5. The vacuum pumping method of the mold according to claim 4, characterized in that, In the step A, a first relief surface (48) which is flat and abuts against a first buffer surface (49) is formed on the outer bottom wall of the hot nozzle sleeve (4), a second relief surface (14) which abuts against a second buffer surface (15) is formed on the fixed mold (1), the second relief surface (14) is an arc surface which is recessed in a direction away from the first relief surface (48), a relief space (8) is formed between the first relief surface (48) and the second relief surface (14), and the relief space (8) communicates with the ventilation gap (6).

6. The vacuum pumping method of the mold according to claim 5, characterized in that, In the step A, a first guiding surface (47) is formed on the outer bottom wall of the hot nozzle sleeve (4), a second guiding surface (13) which is arranged in parallel with the first guiding surface (47) and abuts against the second relief surface (14) is formed on the fixed mold (1), the vertical cross sections of the first guiding surface (47) and the second guiding surface (13) are both inclined and outwardly arranged from bottom to top, the first guiding surface (47) is arranged between the first relief surface (48) and the support wall (42), and a part of the above-mentioned ventilation gap (6) is formed between the first guiding surface (47) and the second guiding surface (13) and communicates with the air extraction channel (41).

7. The vacuum pumping method of the mold according to any one of claims 1-5, characterized in that, In the step A, the support wall (42) is annular, the sealing member (42a) is a first annular sealing ring, the air outlet of the ventilation gap (6) and the air inlet of the air extraction channel (41) are both located inside the first sealing ring, and the air inlet of the air extraction channel (41) is located on one side of the support wall (42) close to the ventilation gap (6).

8. The vacuum pumping method of the mold according to claim 7, characterized in that, In the step B, a cooling circulation channel which is annular is formed on the outer side wall of the hot nozzle sleeve (4), a limiting retaining edge (43) which protrudes outward and is annular is formed on the upper end of the outer side wall of the hot nozzle sleeve (4), the cooling circulation channel is located below the limiting retaining edge (43), the bottom wall of the limiting retaining edge (43) is horizontally arranged, and the second sealing ring (43a) on the bottom wall abuts against the fixed mold (1), and the air outlet of the air extraction channel (41) is located on the outer side wall of the limiting retaining edge (43).

9. The vacuum pumping method of the mold according to claim 8, characterized in that, In the step A, a vertically arranged first air passage (41a) and a horizontally arranged second air passage (41b) are formed on the hot nozzle sleeve (4), the first air passage (41a) and the second air passage (41b) constitute the above-mentioned air extraction channel (41), the second air passage (41b) communicates with the side wall at the upper end of the first air passage (41a), the air inlet of the first air passage (41a) communicates with the ventilation gap (6), and the air outlet of the second air passage (41b) communicates with the air inlet of the exhaust passage (11).

10. The vacuum pumping method of the mold according to claim 9, characterized in that, In the step A, an annular exhaust groove I (42b) is formed on the support wall (42) to communicate the ventilation gap (6) with the air passage I (41a). The outer side wall of the limit retaining edge (43) is attached to the fixed mold (1). An annular exhaust groove II (43c) is formed on the outer side wall of the limit retaining edge (43), and the exhaust groove II (43c) communicates with the air outlet of the air passage II (41b). Two annular sealing grooves (43b) are formed on the outer side wall of the limit retaining edge (43). The air passage II (41b) is arranged between the two sealing grooves (43b). An O-ring (44) is arranged in the sealing groove (43b), and the O-ring (44) abuts against the fixed mold (1) for sealing.

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