A car seat back injection molding die

Abstract

This invention relates to the field of plastic molding and processing technology. The objective is to provide an injection molding mold for an automotive seat backrest, comprising a mold body consisting of a male mold and a female mold. A recessed air-cushion mounting cavity is provided on the surface of the male mold opposite to the plastic part molding area. The air-cushion mounting cavity communicates with a drive cavity located on the back of the male mold. A retractable air-cushion device is provided within the air-cushion mounting cavity. The retractable air-cushion device includes an ejector rod, a retractable sleeve sleeved outside the ejector rod, an inflation and pressurization mechanism, and an air-cushion driving mechanism. Driven by the air-cushion driving mechanism, the retractable air-cushion device can switch between injection molding state, mold opening and locking state, and air-cushion state. Compared with existing methods, this invention results in a lower plastic part deformation rate and better positioning, leading to a higher overall product yield.

Description

Technical Field

[0001] This invention relates to the field of plastic molding and processing technology, specifically to an injection molding mold for an automotive seat back. Background Technology

[0002] In the field of plastic injection molding, the mold ejection mechanism is a core component that ensures the smooth ejection of plastic parts from the mold, guaranteeing product quality and production efficiency. Among them, air ejection devices are particularly crucial in the injection molding production of automotive seat backs due to their advantages of uniform ejection force and minimal damage to plastic parts. As a core component for driving comfort and safety, automotive seat backs not only integrate complex support frame grooves, ventilation hole arrays, and other irregularly shaped structures, but also require a fine texture on the surface to match the interior finish. At the same time, the thickness of some thin-walled areas (such as side wing buffer sections) is often less than 2mm. Traditional mechanical ejector pins are prone to cracking or ejector pin marks due to localized stress concentration. Air ejection devices can avoid such problems by uniformly pressurizing gas, making them a key piece of equipment for ensuring the yield rate of automotive seat back plastic parts.

[0003] The mainstream working mode of existing air ejection devices is the "ejector pin upward ejection" mode: after compressed gas is introduced, the ejector pin first slightly ejects towards the cavity, so that the plastic part and the core surface form a tiny gap. Then the gas diffuses through the gap, and the plastic part is ejected from the male mold (moving mold) by means of gas pressure. However, this method has significant limitations in the injection molding of car seat backrests: On the one hand, the ventilation holes and grooves in the seat backrest plastic parts can easily lead to uneven gas gaps, or the tight shrinkage of the plastic parts around the protruding structures on the core can cause blockage of the gas channels, resulting in weak ejection and local deformation of the plastic parts, which directly affects the backrest support accuracy and assembly compatibility; and because it relies on the upward ejection of the ejector pins, and the ejector pins are of limited size, it is impossible to effectively disperse the local stress at the ejection point, and there is still a significant risk of deformation; on the other hand, during the mold opening stage, the seat backrest plastic parts are large in volume (usually covering an area of ​​more than 0.5㎡) and their center of gravity is prone to shift. Existing air ejector devices lack an active positioning mechanism for the plastic parts, relying only on the shrinkage force of the plastic parts themselves to fit the core. During mold opening, the friction force of the separation of the female mold (fixed mold) and the airflow disturbance can easily cause the plastic parts to shift or fall off, which not only increases the product scrap rate, but may also cause downtime due to the plastic parts jamming the mold, reducing production efficiency.

[0004] Some improvement solutions attempt to enhance stability by optimizing ejector pin materials and adjusting spring preload, but none of them break through the core logic of "ejection-type ventilation" and fail to fundamentally solve the problem of positioning seat back plastic parts and gas channel reliability during the mold opening stage. They cannot meet the high-precision and high-stability injection molding production requirements of automotive parts. Therefore, there is an urgent need for an air ejector technology solution that can achieve stable positioning of plastic parts before mold opening and at the same time ensure the reliable formation of gas channels. Summary of the Invention

[0005] The purpose of this invention is to provide an injection molding mold for car seat backrests, which changes the traditional plastic injection mold air ejector device that first lifts the seat backrest with ejector pins and then injects air to eject it. This invention has the advantages of being less prone to deformation and having a high yield rate.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is: an injection molding mold for an automobile seat back, comprising a mold body composed of a male mold and a female mold, wherein a recessed air-cushion mounting cavity is provided on the surface of the male mold opposite to the plastic part molding area, the air-cushion mounting cavity is connected to a drive cavity located on the back of the male mold, and a retractable air-cushion device is provided in the air-cushion mounting cavity;

[0007] The retractable air ejector device includes an ejector rod, a retractable sleeve sleeved outside the ejector rod, an inflation and pressurization mechanism, and an air ejector drive mechanism. The retractable air ejector device can switch between injection molding state, mold opening and locking state, and air ejector state under the drive of the air ejector drive mechanism.

[0008] In the injection molding state: the end faces of the ejector pin and the retractable sleeve near the female mold are flush with the parting surface of the male mold, so that the end faces of the ejector pin and the retractable sleeve form part of the core;

[0009] In the mold opening and locking state: the retractable sleeve can retract into the air ejector mounting cavity, so that the end face of the retractable sleeve, the inner side of the air ejector mounting cavity, and the surface of the plastic part together form a negative pressure locking cavity;

[0010] In the air-pumped state: the inflation and pressurization mechanism can send pressurized gas into the negative pressure locking cavity to make the gas expand the plastic part wrapped on the male mold; and the ejector rod can continuously push out towards the plastic part to separate the plastic part from the male mold.

[0011] Preferably, annular shoulders are provided on the circumferential surfaces of both ends of the retraction sleeve, and the air-jacking mounting cavity is a stepped hole. The inner diameter of the upper section of the air-jacking mounting cavity matches the outer diameter of the shoulder, and the inner diameter of the lower section matches the outer diameter of the middle section of the retraction sleeve.

[0012] Preferably, the pneumatic push mechanism includes a push plate disposed in the drive cavity and capable of sliding up and down along the drive cavity, and a vertical drive rod is provided on the push plate;

[0013] The lower section of the drive rod and the lower section of the push rod are respectively provided with a first drive rack and a second drive rack extending vertically on opposite sides. A first drive gear and a second drive gear that mesh with each other are provided on one side of the second drive rack. The second drive gear meshes with the second drive rack. There is an idle stroke distance between the upper ends of the first drive gear and the first drive rack to control the timing of the engagement of the first drive rack with the first drive gear. When the first drive rack moves upward, it can engage with the drive gear after the idle stroke distance is completed.

[0014] A rocker arm groove is provided in the male mold on the side corresponding to the air-support mounting cavity and the drive rod. A drive rocker arm is provided in the rocker arm groove. The middle section of the drive rocker arm is hinged to the side wall of the rocker arm groove. One end of the drive rocker arm is connected to the shoulder of the retraction sleeve through a pull-down steel wire, and the other end is provided with a contact wheel, which contacts the bend at the upper end of the drive rod. A reset support spring is provided between the shoulder of the retraction sleeve and the stepped surface of the air-support mounting cavity. During the upward movement of the drive rod, the drive rocker arm can be pressed back into the rocker arm groove before the idle stroke distance ends.

[0015] Preferably, a limiting plate for controlling the lowest position of the push rod is also installed in the drive cavity at the lower end of the push rod.

[0016] Preferably, the mounting cavity is further provided with a vertical guide rod, and the push plate is sleeved on the guide rod and forms a sliding fit with the guide rod.

[0017] Preferably, the push plate facing the female mold is further provided with a reset rod, which passes through and extends to the surface of the male mold.

[0018] Preferably, a sealing plate is provided at the bottom of the driving cavity, and the sealing plate is detachably connected to the male mold; the sealing plate is provided with rod holes for the main push rod of the bottom surface of the push plate to pass through.

[0019] Preferably, the inflation and pressurization mechanism includes an air inlet pipe disposed on the upper side wall of the large-size section of the air inlet mounting cavity, the air inlet pipe passing through the male mold and extending into the drive cavity to connect with the main air pipe.

[0020] Preferably, the inflation and pressurization mechanism further includes a pressure balancing air pipe disposed on the lower side wall of the large-size section of the air top mounting cavity, the pressure balancing air pipe passing through the male mold and extending into the drive cavity to connect with the main air pipe.

[0021] Preferably, the drive cavity is further provided with an adjustment valve, the air inlet pipe and the pressure balancing pipe are both connected to the adjustment valve, and the other port of the adjustment valve is connected to the main air pipe; the push plate and the sealing plate are both provided with pipe holes, and the main air pipe is connected to the air source through the pipe holes.

[0022] The beneficial effects of this invention are mainly reflected in the following aspects: It abandons the traditional method of ejecting the parts by ejecting them with ejector pins and then using a retractable sleeve to reserve space for air ejection. On the one hand, it can directly use air ejection to prevent stress concentration caused by ejector pins and avoid deformation of the plastic parts; on the other hand, the retraction of the retractable sleeve can form a negative pressure locking cavity, which ensures the stability of the plastic parts in the male mold during mold opening and avoids adverse effects such as plastic parts shifting during mold opening, thus ensuring the overall yield of plastic parts. Specifically, during use, the retractable air ejector device is in the injection molding state during injection molding, and the upper surfaces of the retractable sleeve and ejector pin are directly used as the forming part of the mold without affecting normal injection molding. After injection molding is completed and before mold opening, the retractable air ejector device switches to the mold opening locking state: first, the air ejector drive mechanism drives the retractable sleeve to retract. As the retractable sleeve retracts, a negative pressure area (i.e., a negative pressure locking cavity) is formed on the surface of the male mold (the upper section of the air ejector mounting cavity), thereby making the male mold have an adsorption property for the plastic part. This ensures that even if there is interference such as friction from the female mold during mold opening, it will not cause displacement of the plastic part. To mitigate the impact of mold opening, the air ejector device is switched to air ejector mode after mold opening. Pressurized gas is first introduced into the negative pressure locking chamber (upper section of the air ejector mounting chamber) via an inflation and pressurization mechanism. This gas provides rapid cooling to the corresponding part and, as more gas is introduced, gradually widens the gap between the male mold and the part, releasing them from adhesion. After separation, the ejector rod, driven by the air ejector drive mechanism, pushes upwards, continuing to lift the now-separated part until it is completely separated from the male mold. The part can then be removed using its gripper and other supporting equipment. Compared to existing methods, this invention results in lower part deformation and better positioning, leading to a higher overall product yield. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the internal structure of the present invention;

[0024] Figure 2 for Figure 1 Enlarged view of section A in the middle;

[0025] Figure 3 for Figure 1 Enlarged view of section B in the middle;

[0026] Figure 4 for Figure 1 Enlarged view of section C;

[0027] Reference numerals: 0. Plastic part; 1. Male mold; 2. Female mold; 3. Air ejector mounting cavity; 4. Drive cavity; 5. Ejector rod; 6. Retracting sleeve; 7. Shoulder; 8. Ejector plate; 9. Drive rod; 10. First drive rack; 11. Second drive rack; 12. First drive gear; 13. Second drive gear; 14. Rocker arm slot; 15. Drive rocker arm; 16. Pull-down steel wire; 17. Contact wheel; 18. Bend; 19. Reset support spring; 20. Limiting plate; 21. Guide rod; 22. Reset rod; 23. Sealing plate; 24. Main push rod; 25. Air ejector inlet pipe; 26. Main air pipe; 27. Pressure balancing air pipe; 28. Adjusting valve. Detailed Implementation

[0028] This invention relates to an injection molding mold for automotive seat backrests, used for injection molding of plastic seat backrests. Structurally, it comprises a mold body consisting of a male mold 1 and a female mold 2. The mold closing guide device, injection system, hot runner system, and cooling device attached to the female mold 2 and male mold 1 are existing conventional mechanisms and can be designed with reference to existing molds; therefore, they will not be described in detail here.

[0029] The biggest difference between this invention and existing technologies lies in the use of a retractable air-cushion structure, such as... Figure 1 As shown, a recessed air ejector mounting cavity 3 is provided on the surface of the male mold 1, opposite to the molding area of ​​the plastic part 0. The air ejector mounting cavity 3 is connected to the drive cavity 4 located on the back of the male mold 1. A retractable air ejector device is provided inside the air ejector mounting cavity 3. An air ejector drive mechanism is installed in the drive cavity 4, and the air ejector drive mechanism drives the retractable air ejector device installed in the air ejector mounting cavity 3 to move, thereby realizing the state switching.

[0030] The retractable air ejector device includes an ejector rod 5, a retractable sleeve 6 sleeved outside the ejector rod 5, an inflation and pressurization mechanism, and an air ejector drive mechanism. Its overall technical concept is to create space for gas injection by retracting the retractable sleeve 6 downwards; this changes the traditional method where the ejector rod 5 (also called an ejector pin) needs to be pushed upwards to create space for gas injection. This method eliminates the need for the ejector rod 5 to be pushed upwards; instead, air is injected through the outer periphery of the ejector rod 5 (the space left after the retractable sleeve 6 retracts), thus achieving a wider range of air ejection of the plastic part 0. After the plastic part 0 and the male mold 1 are initially separated by air ejection (relieving adhesion), the ejector rod 5 is finally used to eject the plastic part 0.

[0031] The retraction air ejector device of the present invention can switch between injection molding state, mold opening and locking state and air ejector state under the drive of the air ejector driving mechanism.

[0032] (1) In the injection molding state: the end faces of the ejector pin 5 and the retractable sleeve 6 near the female mold 2 are flush with the parting surface of the male mold 1, so that the end faces of the ejector pin 5 and the retractable sleeve 6 constitute part of the core. That is to say, in this state, the end faces of the ejector pin 5 and the retractable sleeve 6 directly serve as part of the parting surface, forming the molding surface for molding the plastic part 0. The structure is as follows. Figure 1 As shown in the image.

[0033] (2) In the mold opening and locking state: The retractable sleeve 6 can retract into the air ejector mounting cavity 3 so that the end face of the retractable sleeve 6, the inner side of the air ejector mounting cavity 3, and the surface of the plastic part 0 together form a negative pressure locking cavity. That is to say, after the retractable sleeve 6 moves downward, as it retracts, the air ejector mounting cavity 3 above its upper end face forms a spatial area. Since there is no gas supply in this spatial area, a negative pressure is formed. This negative pressure can prevent the plastic part 0 from moving due to the relative movement of the male and female molds when the mold is opened, and ensure the positioning stability of the plastic part 0.

[0034] (3) In the air-pump state: the air-pressurizing mechanism can send pressurized gas into the negative pressure locking cavity so that the gas expands the plastic part 0 wrapped on the male mold 1, realizing the initial separation of the plastic part 0 and the male mold 1 (relieving adhesion). And the ejector rod 5 can continuously push out towards the plastic part 0 so that the plastic part 0 is separated from the male mold 1 (complete separation).

[0035] In general use, during injection molding, the retractable air ejector device is in the injection state, and the upper surfaces of the retractable sleeve 6 and ejector pin 5 are directly used as the forming part of the mold, without affecting normal injection molding. After injection molding is completed and before mold opening, the retractable air ejector device switches to the mold opening locking state: first, the air ejector drive mechanism drives the retractable sleeve 6 to retract. As the retractable sleeve 6 retracts, a negative pressure area (i.e., a negative pressure locking cavity) is formed on the surface of the male mold 1 (the upper section of the air ejector mounting cavity 3), which makes the male mold 1 have an adhesive property to the plastic part 0. This ensures that even if there is interference such as friction from the female mold 2 during the mold opening process, it will not affect the position of the plastic part 0. To ensure the stability of the plastic part 0's position, after mold opening, the retractable air ejector device switches to air ejector mode: Pressurized gas is first introduced into the negative pressure locking chamber (upper section of air ejector mounting chamber 3) via the inflation and pressurization mechanism. This gas serves two purposes: firstly, it allows for further rapid cooling of the corresponding plastic part 0; secondly, as more gas is introduced, it gradually widens the gap between the male mold 1 and the plastic part 0, causing them to separate. After separation, the ejector rod 5, driven by the air ejector drive mechanism, pushes upwards, continuing to push the now-separated plastic part 0 until it is completely separated from the male mold 1. The plastic part 0 can then be removed using its gripper and other supporting equipment. Compared to existing methods, this invention results in a lower deformation rate and better positioning of the plastic part 0, leading to a higher overall product yield.

[0036] From the structure of the retraction sleeve 6, it generally adopts an I-beam structure, combined with... Figure 1-3 As shown, annular shoulders 7 are provided on the circumferential surfaces of both ends of the retractable sleeve 6. The air-jacking mounting cavity 3 is a stepped hole, with the upper section being larger to accommodate the shoulders 7 and the lower section being smaller to accommodate the middle section of the retractable sleeve 6. The inner diameter of the upper section of the air-jacking mounting cavity 3 matches the outer diameter of the shoulders 7, and the inner diameter of the lower section matches the outer diameter of the middle section of the retractable sleeve 6, thereby allowing the retractable sleeve 6 to slide up and down within the air-jacking mounting cavity 3, while also limiting its vertical position.

[0037] Another core aspect of this invention lies in the overall driving of the retractable air ejector device. Since injection molding machines are typically equipped with a push rod (such as...) for driving the ejection action... Figure 1 The main push rod 24 shown in the figure is used to adjust the multiple action states of the retractable air top device so that the push rod moves in one direction.

[0038] like Figure 1 As shown, the pneumatic push mechanism of the present invention includes a push plate 8 disposed in the drive cavity 4 and capable of sliding up and down along the drive cavity 4, and a vertical drive rod 9 is disposed on the push plate 8.

[0039] like Figure 4 As shown, the lower sections of the drive rod 9 and the push rod 5 are respectively provided with a first drive rack 10 and a second drive rack 11 extending vertically on opposite sides. A first drive gear 12 and a second drive gear 13 meshing with each other are provided on one side of the second drive rack 11. The second drive gear 13 meshes with the second drive rack 11. There is a free travel distance between the upper ends of the first drive gear 12 and the first drive rack 10 to control the engagement timing of the first drive rack 10 and the first drive gear 12. When the first drive rack 10 moves upward, it can mesh with the first drive gear 12 after the free travel distance is completed. In other words, during the upward movement of the drive rod 9, the driving of the first drive gear 12 has a lag; it is driven after the retraction sleeve 6 is driven. The first drive rack 10 does not mesh with the first drive gear 12 in the first segment of its movement, but rather in the later part of its movement.

[0040] Combination Figure 1 and 2As shown, a swing rod groove 14 is provided in the male mold 1 on the side corresponding to the drive rod 9 of the air-supported cavity 3. A drive swing rod 15 is provided in the swing rod groove 14, and the middle section of the drive swing rod 15 is hinged to the side wall of the swing rod groove 14. One end of the drive swing rod 15 is connected to the shoulder 7 of the retraction sleeve 6 through a pull-down steel wire 16, and the other end is provided with a contact wheel 17, which contacts the bend 18 provided on the upper end of the drive rod 9. When the drive rod 9 moves upward, it will drive the drive swing rod 15 to swing, thereby dragging the pull-down steel wire 16 and driving the retraction sleeve 6 to descend. When the drive rod 9 continues to move upward, as it fully presses the drive swing rod 15 into the swing rod groove 14, it essentially completes the locking of the position of the retraction sleeve 6. Further upward movement of the drive rod 9 will not interfere with the position of the retraction sleeve 6. In the following stroke, the main function of the drive rod 9 is to drive the action of the push rod 5. Therefore, during the upward movement of the drive rod 9, the drive rocker arm 15 can be pressed back into the rocker arm slot 14 before the end of the idle travel distance.

[0041] Like the head Figure 3 As shown, in order to realize the return of the retractable sleeve 6 in the injection molding state, a reset support spring 19 is provided between the shoulder 7 of the retractable sleeve 6 and the stepped surface of the air top mounting cavity 3. After the drive rod 9 is fully retracted, the retractable sleeve 6 can be reset (switched to the position in the injection molding state) through the reset support spring 19.

[0042] Of course, in order to limit the downward movement of the push rod 5, a limiting support plate 20 for controlling the lowest position of the push rod 5 is also installed in the drive cavity 4 at the lower end of the push rod 5. To further ensure the stability of the movement of the push plate 8, such as... Figure 1 As shown, a vertical guide rod 21 can also be provided in the mounting cavity, and the push plate 8 is sleeved on the guide rod 21 and forms a sliding fit with the guide rod 21. In order to realize the reset of the push plate 8 itself, a reset rod 22 is also provided on the side of the push plate 8 facing the female mold 2, and the reset rod 22 passes through and extends to the surface of the male mold 1.

[0043] To facilitate overall installation, a sealing plate 23 is provided at the bottom of the drive cavity 4, and the sealing plate 23 is detachably connected to the male mold 1. The sealing plate 23 is provided with rod holes through which the main push rod 24 on the bottom surface of the push plate 8 passes.

[0044] Regarding the inflation and pressurization mechanism of the present invention, as follows: Figure 1 and 3As shown, it includes an air inlet pipe 25 disposed on the upper side wall of the large-size section of the air ejector mounting cavity 3. The air inlet pipe 25 passes through the male mold 1 and extends into the drive cavity 4, connecting with the main air pipe 26. Since the pressure inside the cavity is relatively high during injection molding, relying solely on the reset support spring 19 may not be sufficient to completely guarantee pressure balance. Therefore, the inflation and pressurization mechanism of this invention also includes a pressure balancing air pipe 27 disposed on the lower side wall of the large-size section of the air ejector mounting cavity 3. The pressure balancing air pipe 27 passes through the male mold 1 and extends into the drive cavity 4, connecting with the main air pipe 26. A certain amount of gas can be injected into the air ejector mounting cavity 3 below the shoulder platform 7 through the pressure balancing air pipe 27, thereby ensuring that the injection molding requirements are met. Of course, during state adjustment, air can be released through the pressure balancing air pipe 27 to avoid the formation of an airflow dead zone below the shoulder platform 7, which would affect the movement of the retraction sleeve 6.

[0045] To better facilitate the adjustment and switching of each pipeline, an adjustment valve 28 is also provided in the drive chamber 4. The air inlet pipe 25 and the pressure balancing pipe 27 are both connected to the adjustment valve 28, and another interface of the adjustment valve 28 is connected to the main air pipe 26. Both the push plate 8 and the sealing plate 23 are provided with pipe holes, through which the main air pipe 26 is connected to the air source. The adjustment valve 28 is a solenoid valve with functions such as individually closing / opening the air inlet pipe 25 and the pressure balancing pipe 27, or jointly opening / closing both. This type of valve is common in the prior art and will not be described further in this invention. Of course, it is also feasible to achieve separate air intake and exhaust for the two air pipes through separate pipelines.

Claims

1. An injection molding die for an automotive seat backrest, characterized by: The utility model relates to a kind of gas lift ejection devices, including the mould main body formed by male die (1) and female die (2), the surface of the male die (1) is set with the concave gas lift installation cavity (3) in the position opposite to the forming area of plastic part (0), the gas lift installation cavity (3) is communicated with the driving cavity (4) located at the back of male die (1), retractable gas lift device is set in the gas lift installation cavity (3); The retractable gas lift device includes a ejector rod (5), a retractable sleeve (6) that is sleeved on the ejector rod (5), an inflation pressurizing mechanism, and a gas lift driving mechanism. The retractable gas lift device can switch among the injection state, the mold opening locking state, and the gas lift state under the driving of the gas lift driving mechanism. In the injection state, the end surface of the ejector rod (5) and the retractable sleeve (6) close to one end of the female die (2) is flush with the parting surface of the male die (1), so that the end surface of the ejector rod (5) and the retractable sleeve (6) forms part of the core. In the mold opening locking state, the retractable sleeve (6) can retract into the gas lift installation cavity (3), so that the end surface of the retractable sleeve (6), the inner surface of the gas lift installation cavity (3), and the surface of the plastic part (0) together enclose a negative pressure locking cavity. In the gas lift state, the inflation pressurizing mechanism can send pressurized gas into the negative pressure locking cavity, so that the gas can support the plastic part (0) wrapped on the male die (1) to be opened; and the ejector rod (5) can continuously eject the plastic part (0), so that the plastic part (0) is separated from the male die (1). The circumferential surface of both ends of the retractable sleeve (6) is provided with an annular shoulder (7). The gas lift installation cavity (3) is a stepped hole, the inner diameter of the upper section of the gas lift installation cavity (3) matches the outer diameter of the shoulder (7), and the inner diameter of the lower section matches the outer diameter of the middle section of the retractable sleeve (6). The gas lift driving mechanism includes a push plate (8) arranged in the driving cavity (4) and capable of sliding up and down in the driving cavity (4). A vertical driving rod (9) is arranged on the push plate (8). The side opposite to the lower section of the ejector rod (5) of the lower section of the driving rod (9) is respectively provided with a first driving rack (10) and a second driving rack (11) extending in the vertical direction. The side of the second driving rack (11) is provided with a first driving gear (12) and a second driving gear (13) meshing with each other. The second driving gear (13) is meshed with the second driving rack (11). The first driving gear (12) and the upper end of the first driving rack (10) have an idle stroke distance for controlling the timing of meshing of the first driving rack (10) and the first driving gear (12). When the first driving rack (10) moves upward, it can be meshed with the first driving gear (12) after the idle stroke distance ends. The gas top mounting cavity (3) is provided with a swing rod groove (14) on the side of the male mold (1) corresponding to the driving rod (9), the swing rod groove (14) is provided with a driving swing rod (15), the middle section of the driving swing rod (15) is hinged to the side wall of the swing rod groove (14); one end of the driving swing rod (15) is connected to the shoulder (7) of the retraction sleeve (6) through a downward steel wire (16), the other end is provided with a contact wheel (17) and is in contact with the elbow (18) provided on the upper end of the driving rod (9) through the contact wheel (17); the reset support spring (19) is arranged between the shoulder (7) of the retraction sleeve (6) and the stepped surface of the gas top mounting cavity (3); during the upward movement of the driving rod (9), the driving swing rod (15) can be pressed back into the swing rod groove (14) before the end of the idle stroke distance.

2. The automobile seat back injection molding mold according to claim 1, characterized by: A limiting supporting plate (20) for controlling the lowest position of the ejector rod (5) is further arranged in the driving cavity (4) at the lower end of the ejector rod (5).

3. The automobile seat back injection molding mold according to claim 1, characterized in that: A vertical guide rod (21) is further arranged in the mounting cavity, the push plate (8) is sleeved outside the guide rod (21) and forms a sliding fit with the guide rod (21).

4. The automobile seat back injection molding mold according to claim 1, characterized in that: A reset rod (22) is further arranged on the side of the push plate (8) facing the female mold (2), the reset rod (22) penetrates and extends to the surface of the male mold (1).

5. The automobile seat back injection molding mold according to claim 1, characterized in that: An envelope plate (23) is arranged at the bottom of the driving cavity (4), the envelope plate (23) is detachably connected with the male mold (1); a rod hole is arranged on the envelope plate (23) and penetrates by the main push rod (24) at the bottom of the push plate (8).

6. The automotive seat back injection molding mold of claim 5, wherein: The air inflation and pressure mechanism comprises an air top air inlet pipe (25) arranged on the upper side wall of the large size section of the air top mounting cavity (3), the air top air inlet pipe (25) penetrates the male mold (1) and extends into the driving cavity (4) and is connected with the total air pipe (26).

7. The automotive seat back injection molding mold of claim 6, wherein: The air inflation and pressure mechanism further comprises a pressure balance air pipe (27) arranged on the lower side wall of the large size section of the air top mounting cavity (3), the pressure balance air pipe (27) penetrates the male mold (1) and extends into the driving cavity (4) and is connected with the total air pipe (26).

8. The automotive seat back injection molding mold of claim 7, wherein: The driving cavity (4) is further provided with a cutting valve (28), the air top air inlet pipe (25) and the pressure balance air pipe (27) are connected with the cutting valve (28), the other interface of the cutting valve (28) is connected with the total air pipe (26); the push plate (8) and the envelope plate (23) are both provided with a pipe hole, and the total air pipe (26) is connected to the air source through the pipe hole.

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