A secondary ejection mechanism of injection mold based on a seesaw structure

Abstract

The utility model relates to the technical fields of injection mold, especially to a secondary ejection mechanism of injection mold based on seesaw structure, aims at solving the problem of jam when the stepped ejector pin ejects the thin injection molded part. It includes the ejection mechanism assembled in the back mould, and the ejection mechanism contains the fixed ejection bottom plate and the ejection panel, and the ejection panel is equipped with the ejector pin assembly containing the stepped ejector pin and the compound ejector pin; the compound ejector pin corresponds to the corner of the injection molded part, and the secondary ejection is realized through the seesaw mechanism, which contains the seesaw rotatingly connected with the ejection bottom plate, and the both ends abut against the compound ejector pin and the auxiliary rod. When ejecting, the auxiliary rod hits the back mould plate and moves downward at the end of the ejection stroke, and the compound ejector pin is pushed and ejected by the seesaw lever action, and the jam of the injection molded part at the stepped ejector pin step position is removed. The mechanism does not need additional power source, and can adapt to different injection molded parts by adjusting the number and position of the compound ejector pin, and the ejection is stable, the structure is simple, and the demolding efficiency and product quality can be improved.

Description

Technical Field

[0001] This utility model relates to the technical field of injection molds, and in particular to a secondary ejection mechanism for injection molds based on a seesaw structure. Background Technology

[0002] In the field of injection molding, for thin injection molded parts, multiple reinforcing ribs are typically formed on one side of the rear mold cavity to improve their structural strength. Due to the structural requirements of the injection molded parts, these reinforcing ribs are often distributed dispersedly and their extension directions intersect. To achieve smooth demolding of the injection molded parts, existing technologies generally employ multiple stepped ejector pins corresponding to each reinforcing rib. By matching the step position at the top of the stepped ejector pin with the reinforcing rib, the reinforcing ribs in different directions are ejected simultaneously, pushing the injection molded part away from the rear mold core.

[0003] However, the existing ejection method has significant technical defects: due to the large number and staggered orientation of the stepped ejector pins, the reinforcing ribs of various parts of the injection molded part will interact with the steps of the corresponding stepped ejector pins during the ejection process, which can easily cause the reinforcing ribs to get stuck at the step of the stepped ejector pin (i.e., the "ejector pin jamming" problem). Once jamming occurs, it will not only prevent the injection molded part from being demolded normally, but may also lead to deformation of the injection molded part, breakage of the reinforcing ribs, and even mold failures such as bending and damage of the stepped ejector pins, seriously affecting production efficiency and product qualification rate.

[0004] To address the issue of ejector pin jamming, various secondary ejection mechanisms have emerged in existing technologies. These include mechanisms driven by dual ejector plates or those that use springs to directly push the ejector pins, resulting in delayed ejection. However, dual ejector plate structures require additional drive components (such as hydraulic or pneumatic cylinders), leading to complex mold structures, increased costs, and a larger footprint within the mold, making them unsuitable for small molds. Spring-driven secondary ejection, on the other hand, suffers from easily decaying spring force and uncontrollable ejection stroke, making it prone to secondary ejection failure after prolonged use and unable to reliably release jamming.

[0005] Therefore, there is an urgent need for a simple secondary ejection mechanism that requires no additional power source and provides stable and reliable ejection, in order to solve the jamming problem during the ejection of existing stepped ejector pins, while also being compatible with injection molded parts of different structures to ensure demolding efficiency and product quality. Utility Model Content

[0006] To overcome the shortcomings of the prior art, this utility model aims to provide a technical solution that can solve the above problems.

[0007] This utility model provides a secondary ejection mechanism for injection molds based on a seesaw structure, comprising: An ejection mechanism is assembled on one side of the rear mold. The ejection mechanism is slidably connected to the rear mold plate through a guide device and is reset by a reset rod. The ejection mechanism includes a fixed ejection base plate and an ejection panel. The ejection base plate drives the ejection panel to be ejected upward under the drive of the injection molding machine ejector rod. The ejector panel is provided with an ejector pin assembly, which includes multiple stepped ejector pins and at least one composite ejector pin. The composite ejector pin corresponds to the corner position of the injection molded part and is ejected twice through a seesaw mechanism. The seesaw mechanism includes a seesaw rotatably connected to the ejection base plate and a composite ejector pin and an auxiliary rod that abut against its two ends. The composite ejector pin is pushed out again at the end of the ejection stage by the downward movement of the auxiliary rod.

[0008] Furthermore: the ejector pin assembly includes two, three, or four composite ejector pins, as well as seesaws and auxiliary rods that match the composite ejector pins one by one; If there are two composite ejector pins, they are respectively assembled at the two corner positions corresponding to one diagonal of the injection molded part; If there are three composite ejector pins, they are respectively assembled at any three corner positions of the injection molded part; If there are four composite ejector pins, they are respectively assembled at the four corners of the injection molded part.

[0009] Furthermore: the lower end of the ejector panel is provided with multiple countersunk holes, each of which is divided into a small-diameter guide section and a large-diameter receiving section along the axial direction; the lower ends of the auxiliary rod and the composite ejector pin are provided with limiting heads with a diameter larger than the diameter of their own rod bodies. When the auxiliary rod is inserted into the countersunk hole of the ejector panel, its limiting head is received in the large-diameter receiving section of the countersunk hole, and the rod body is inserted in the small-diameter guide section; when the composite ejector pin is inserted into the countersunk hole of the ejector panel, its limiting head is received in the large-diameter receiving section of the countersunk hole, and the rod body is inserted in the small-diameter guide section.

[0010] Furthermore, the top of the auxiliary rod can make a limiting impact with the rear template at the end of the ejection stroke, and move downward along its axis under the impact to drive the lever movement of the seesaw, thereby pushing the composite ejector pin to achieve secondary ejection.

[0011] Furthermore: a composite spring is provided in the countersunk hole corresponding to the composite ejector pin. One end of the composite spring abuts against the ejector panel, and the other end abuts against the limiting head of the composite ejector pin. During the reset process of the ejector mechanism, the composite spring drives the composite ejector pin to move downwards to reset, and drives the auxiliary rod to reset upwards to the initial position through the reverse rotation of the seesaw.

[0012] Furthermore, the timing of the secondary ejection is as follows: after the ejection mechanism drives the stepped ejector to complete the first ejection stroke, the composite ejector triggers the secondary ejection, causing the composite ejector to lag behind the stepped ejector and generate an additional ejection stroke, so as to release the jamming of the injection molded part at the step of the stepped ejector.

[0013] Furthermore: the ejector base plate is provided with a receiving space corresponding to the seesaw, the middle part of the seesaw is pivotally connected to the ejector base plate by a pin, and the seesaw moves within the receiving space; the two ends of the seesaw abut against the bottom end of the composite ejector pin and the bottom end of the auxiliary rod, respectively, and the torque transmission and stroke amplification are realized through the lever principle.

[0014] Furthermore: the bottom of the seesaw is provided with a limiting plane near the end of the composite ejector pin; in the initial state of injection molding after mold closing, the bottom of the composite ejector pin abuts against one end of the seesaw, causing the seesaw to tilt towards the auxiliary rod and drive the auxiliary rod to remain in an upward-push state, and the limiting plane forms a limiting abutment with the bottom of the accommodating space, restricting the seesaw from continuing to rotate towards the auxiliary rod, so as to ensure that the top of the composite ejector pin remains in the injection cavity.

[0015] Furthermore, the top surface of the ejector panel is provided with a limiting block; when the ejector mechanism ejects upward to the maximum displacement, the limiting block abuts against the lower end surface of the rear template to limit the maximum relative displacement between the ejector panel and the rear template.

[0016] Compared with the prior art, the beneficial effects of this utility model are: ①Efficiently solves the problem of ejector pin jamming By combining the design of "seesaw mechanism + composite ejector pin", the composite ejector pin triggers a second ejection after the stepped ejector pin completes one ejection, and the delay generates an additional ejection stroke. This can accurately eject the injection molded part from the staggered stepped ejector pin steps, completely avoid the jamming of the reinforcing ribs, ensure the normal demolding of the injection molded part, and reduce the product scrap rate and mold failure rate.

[0017] ② The structure is simple and requires no additional power source. The secondary ejection is triggered by the limiting impact between the auxiliary rod and the rear template. Power is transmitted through the lever principle of the seesaw, eliminating the need for additional drive components such as hydraulic cylinders and air cylinders. This simplifies the mold structure, reduces mold manufacturing and maintenance costs, saves internal installation space, and is suitable for small injection molds.

[0018] ③ Stable ejection and strong adaptability By adjusting the number of composite ejector pins (2 / 3 / 4) and their assembly position (diagonal / triangle / corner), various ejection modes such as symmetrical ejection and triangular support ejection can be formed, which can be adapted to injection molded parts with different structures such as small thin-walled parts, asymmetrical parts, and large densely reinforced parts. During the ejection process, the injection molded parts are subjected to uniform force, reducing the risk of deformation and ensuring the quality of product molding.

[0019] ④ The mechanism is reliable in operation and has a long service life. By limiting the maximum ejection displacement with a limiting block, achieving automatic reset with a composite spring, and ensuring the stability of the initial position with a seesaw limiting plane, multiple sets of limiting and reset structures work together to ensure precise action and stable operation of the ejection mechanism, avoiding component instability or damage caused by overtravel, and extending the service life of the mold and ejection mechanism.

[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a cross-sectional schematic diagram of the ejection mechanism of this utility model in the mold closing state; Figure 2 This is a cross-sectional schematic diagram of the first ejection stroke state of this utility model; Figure 3 This is a cross-sectional schematic diagram of the secondary ejection stroke state of this utility model; Figure 4 This is a structural schematic diagram of the seesaw mechanism of this utility model; Figure 5 This is a cross-sectional schematic diagram of the rear template and the rear mold core of this utility model; Figure 6 This is a structural schematic diagram of the ejector base plate and ejector panel of this utility model.

[0023] The reference numerals and names in the figure are as follows: 10 Rear mold plate; 11 Rear mold core; 12 Guide device; 13 Reset rod; 20 Ejection mechanism; 21 Limiting block; 22 Ejection base plate; 23 Accommodating space; 24 Ejection panel; 25 Guide section; 26 Accommodating section; 30 Ejector pin assembly; 31 Stepped ejector pin; 32 Composite ejector pin; 33 Composite spring; 34 Seesaw; 35 Limiting plane; 36 Auxiliary rod; 40 Injection part. Detailed Implementation

[0024] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] Please see Figures 1 to 6 In this embodiment of the present invention, a secondary ejection mechanism for an injection mold based on a seesaw structure includes: An ejection mechanism 20 is assembled on one side of the rear mold. The ejection mechanism 20 is slidably connected to the rear mold plate 10 through a guide device 12 and is reset by a reset rod 13. The ejection mechanism 20 includes a fixed ejection base plate 22 and an ejection panel 24. The ejection base plate 22 drives the ejection panel 24 to be ejected upward under the drive of the injection molding machine ejector rod. The ejector panel 24 is provided with an ejector pin assembly 30, which includes multiple stepped ejector pins 31 and at least one composite ejector pin 32. The composite ejector pin 32 corresponds to the corner position of the injection molded part 40 and is ejected twice through a seesaw mechanism. The seesaw mechanism includes a seesaw 34 rotatably connected to the ejection base plate 22, and a composite ejector pin 32 and an auxiliary rod 36 that abut against its two ends. The composite ejector pin 32 is pushed out again at the end of the ejection stage by the downward movement of the auxiliary rod 36.

[0026] Specifically, in the injection molding of a relatively thin injection molded part 40, to improve the structural strength of the injection molded part 40, it is usually necessary to form multiple reinforcing ribs on one side of the rear mold cavity, and these reinforcing ribs are distributed dispersedly and in staggered directions. To ensure that the injection molded part 40 can be demolded smoothly, the mold is provided with multiple stepped ejector pins 31, which eject corresponding to the reinforcing ribs. However, due to the large number of stepped ejector pins 31 and their different directions, interaction forces are easily generated during the ejection process, causing the reinforcing ribs of the injection molded part 40 to get stuck at the stepped parts of the stepped ejector pins 31, thus preventing the injection molded part 40 from being demolded normally.

[0027] To solve the above problems, this utility model provides a composite ejector pin 32 at the corner of the injection molded part 40, and a seesaw 34 structure at its bottom. One end of the seesaw 34 abuts against the composite ejector pin 32, and the other end abuts against the auxiliary rod 36. After the ejection mechanism 20 completes the normal ejection stroke, the auxiliary rod 36, during its continued downward movement, pushes the composite ejector pin 32 outward again through the leverage of the seesaw 34, so that the composite ejector pin 32 forms a secondary ejection stroke relative to the other stepped ejector pins 31. Through this secondary ejection action, the injection molded part 40 can be smoothly ejected from the stepped part of the stepped ejector pins 31, avoiding jamming of the injection molded part 40, ensuring normal demolding of the injection molded part 40, and improving the reliability of the ejection process.

[0028] like Figures 1 to 4 As shown, preferably, the ejector pin assembly 30 includes two, three, or four composite ejector pins 32, and a seesaw 34 and an auxiliary rod 36 that are matched one-to-one with the composite ejector pins 32. If there are two composite ejector pins 32, they are respectively assembled at the two corner positions corresponding to one diagonal of the injection molded part 40; If there are three composite ejector pins 32, they are respectively assembled at any three corner positions of the injection molded part 40; If there are four composite ejector pins 32, they are respectively assembled at the four corners of the injection molded part 40.

[0029] Specifically, to optimize the secondary ejection effect and adapt to injection molded parts 40 with different structures and sizes, precise ejection can be achieved by adjusting the number and assembly position of the composite ejector pins 32, including the following preferred configurations: Double composite ejector pins 32 (diagonal configuration): One composite ejector pin 32 is installed at each of the two corners corresponding to any diagonal of the injection molded part 40. Each composite ejector pin 32 is matched with a set of seesaws 34 and auxiliary rods 36. During ejection, the two sets of secondary ejection units are triggered synchronously, applying symmetrical ejection forces from both ends of the diagonal. This can prevent the small thin-walled injection molded part 40 from tilting due to force offset, while reducing ejection stress concentration and ensuring that the injection molded part 40 smoothly detaches from the stepped ejector pins 31.

[0030] Three-composite ejector pins 32 (arbitrary triangular configuration): For injection molded parts 40 with asymmetrical structures such as protrusions or notches at one corner, one composite ejector pin 32 is installed at each of the three corner positions. Each composite ejector pin 32 corresponds to a set of seesaws 34 and auxiliary rods 36. During the secondary ejection stage, the three sets of units move synchronously to form a "triangular support ejection", which can balance the ejection force of different parts of the injection molded part 40, avoid excessive local force leading to corner damage, and effectively release the jamming of the stepped ejector pins 31.

[0031] Four composite ejector pins 32 (preferred configuration at four corners): For large thin-walled injection molded parts 40 or injection molded parts 40 with dense reinforcing ribs, composite ejector pins 32 are installed at each of the four corners. Each composite ejector pin 32 corresponds to a set of seesaws 34 and auxiliary rods 36. During ejection, the four sets of units are triggered synchronously, applying uniform and symmetrical ejection force from the four corners. This can minimize the risk of deformation of the injection molded part 40. At the same time, the delayed ejection at the four corners completely disengages from the staggered stepped ejector pins 31, achieving "damage-free and high-efficiency" demolding, which is the optimal implementation of this utility model.

[0032] like Figure 1 and Figure 6As shown, preferably, the lower end of the ejector panel 24 is provided with multiple countersunk holes, each of which is sequentially divided into a small-diameter guide section 25 and a large-diameter receiving section 26 along the axial direction; the lower ends of the auxiliary rod 36 and the composite ejector pin 32 are provided with limiting heads with a diameter larger than their own rod diameter. When the auxiliary rod 36 is inserted into the countersunk hole of the ejector panel 24, its limiting head is received in the large-diameter receiving section 26 of the countersunk hole, and the rod body is inserted into the small-diameter guide section 25; when the composite ejector pin 32 is inserted into the countersunk hole of the ejector panel 24, its limiting head is received in the large-diameter receiving section 26 of the countersunk hole, and the rod body is inserted into the small-diameter guide section 25.

[0033] Specifically, the lower end of the ejector panel 24 is machined with multiple countersunk holes, each of which is divided axially into a small-diameter guide section 25 and a large-diameter receiving section 26. The lower ends of both the auxiliary rod 36 and the composite ejector pin 32 are provided with limiting heads with a diameter larger than their own rod bodies. During assembly, the rod body of the auxiliary rod 36 passes through the small-diameter guide section 25 of the countersunk hole, and its limiting head is accommodated within the large-diameter receiving section 26; similarly, the rod body of the composite ejector pin 32 passes through the small-diameter guide section 25 of the countersunk hole, and its limiting head is also accommodated within the large-diameter receiving section 26.

[0034] The advantages of this structural design are: the small-diameter guide section 25 provides precise axial guidance for the rods of the auxiliary rod 36 and the composite ejector pin 32, preventing the rods from deflecting during ejection or resetting; the large-diameter receiving section 26 forms an axial limit on the limiting head, preventing the auxiliary rod 36 and the composite ejector pin 32 from falling out of the ejection panel 24, and ensuring the structural stability of the ejection mechanism 20 during repeated actions.

[0035] like Figure 2 and Figure 3 As shown, preferably, the top of the auxiliary rod 36 can make a limiting impact with the rear template 10 at the end of the ejection stroke, and move downward along its axis under the impact to drive the lever movement of the seesaw 34, thereby pushing the composite ejector pin 32 to achieve secondary ejection.

[0036] Specifically, the top of the auxiliary rod 36 will make a limiting impact with the rear mold plate 10 at the end of the ejection stroke. The specific action process is as follows: when the ejector rod of the injection molding machine drives the ejector base plate 22 to move upward, the ejector panel 24 drives the auxiliary rod 36 to move upward synchronously; when the ejection mechanism 20 completes most of the ejection stroke (the stepped ejector pin 31 initially ejects the injection molded part 40 away from the rear mold core 11), the top of the auxiliary rod 36 contacts the rear mold plate 10 and generates an impact force.

[0037] Under the impact force, the auxiliary rod 36 moves downward along the axis, and its bottom end pushes one end of the seesaw 34 to deflect downward; by means of the lever principle of the seesaw 34, the other end of the seesaw 34 tilts upward, thereby pushing the composite ejector pin 32 upward to produce a secondary ejection action. This method of triggering secondary ejection through mechanical impact does not require an additional power source, and can be achieved simply by matching the stroke of the ejection process. The structure is simple and the action triggering is precise and reliable.

[0038] like Figure 2 , Figure 3 and Figure 4 As shown, preferably, a composite spring 33 is provided in the countersunk hole corresponding to the composite ejector pin 32. One end of the composite spring 33 abuts against the ejector panel 24, and the other end abuts against the limiting head of the composite ejector pin 32. During the reset process of the ejector mechanism 20, the composite spring 33 drives the composite ejector pin 32 to move downwards to reset, and drives the auxiliary rod 36 to reset upwards to the initial position through the reverse rotation of the seesaw 34.

[0039] Specifically, a composite spring 33 is installed in the countersunk hole corresponding to the composite ejector pin 32. One end of the spring abuts against the bottom of the countersunk hole of the ejector panel 24, and the other end abuts against the limiting head of the composite ejector pin 32.

[0040] When the ejection mechanism 20 completes the ejection operation and enters the reset process, the limiting impact state between the rear template 10 and the auxiliary rod 36 is released. At this time, the elastic restoring force of the composite spring 33 drives the composite ejector pin 32 to move downward, restoring it to its initial position. During the downward movement of the composite ejector pin 32, its bottom end pushes one end of the seesaw 34 to deflect upward. Through the reverse lever action of the seesaw 34, the auxiliary rod 36 is driven upward, eventually restoring the auxiliary rod 36 to its initial position as well.

[0041] The composite spring 33 enables the automatic reset of the composite ejector pin 32 and the auxiliary rod 36, ensuring that the ejection mechanism 20 returns to its initial state after each ejection cycle, thus guaranteeing continuous and stable mold production and improving the practicality and cyclic performance of the mechanism.

[0042] like Figures 1 to 3 As shown, preferably, the timing of the secondary ejection is as follows: after the ejection mechanism 20 drives the stepped ejector pin 31 to complete the first ejection stroke, the composite ejector pin 32 triggers the secondary ejection, so that the composite ejector pin 32 lags behind the stepped ejector pin 31 to generate an additional ejection stroke, so as to release the jamming of the injection molded part 40 at the step of the stepped ejector pin 31.

[0043] Specifically, the secondary ejection of this ejection mechanism 20 has a clear action sequence: during the ejection stage of the ejection mechanism 20, the ejection base plate 22 first drives the ejection panel 24, the stepped ejector pin 31 and the compound ejector pin 32 to move upward synchronously. At this time, the stepped ejector pin 31 completes the first ejection stroke and initially ejects the injection molded part 40 from the rear mold core 11.

[0044] After the stepped ejector pin 31 completes its first ejection stroke, the top of the auxiliary rod 36 makes a limiting impact with the rear template 10, triggering the secondary ejection of the composite ejector pin 32, causing the composite ejector pin 32 to lag behind the stepped ejector pin 31 and generate an additional ejection stroke.

[0045] The core value of this timing design lies in the fact that after the stepped ejector pins 31 have detached most of the structure of the injection molded part 40, the delayed ejection of the composite ejector pins 32 can precisely act on the four corners of the injection molded part 40, applying additional ejection force to the injection molded part 40, thereby completely releasing the injection molded part 40 from the step section of the stepped ejector pins 31. This timing ensures that the injection molded part 40 can smoothly detach from the top of the multi-directionally intersecting stepped ejector pins 31, avoiding deformation and damage to the injection molded part 40, and also protecting the service life of the ejector pin assembly 30.

[0046] like Figure 4 and Figure 6 As shown, preferably, the ejector base plate 22 is provided with a receiving space 23 corresponding to the seesaw 34. The middle part of the seesaw 34 is pivotally connected to the ejector base plate 22 by a pin, and the seesaw 34 moves within the receiving space 23. The two ends of the seesaw 34 abut against the bottom end of the composite ejector pin 32 and the bottom end of the auxiliary rod 36, respectively, and the torque transmission and stroke amplification are realized through the lever principle.

[0047] Specifically, the ejector base plate 22 is provided with a receiving space 23 for the seesaw 34. This space provides sufficient range of motion for the rotation of the seesaw 34, and avoids interference between the seesaw 34 and the ejector base plate 22 during the rotation process.

[0048] The middle part of the seesaw 34 is pivotally connected to the ejector base plate 22 via a pin. This connection allows the seesaw 34 to rotate flexibly around the pin, providing a stable fulcrum for the lever motion. The two ends of the seesaw 34 abut against the bottom end of the composite ejector pin 32 and the bottom end of the auxiliary rod 36, respectively. When the auxiliary rod 36 moves downward, its bottom end pushes one end of the seesaw 34 downward, and with the help of the pin's fulcrum, the other end of the seesaw 34 tilts upward, thereby pushing the composite ejector pin 32 upward.

[0049] This structural design not only achieves effective torque transmission, but also amplifies the ejection stroke through the lever principle, ensuring that the composite ejector pin 32 can generate sufficient secondary ejection distance, completely eliminating the jamming of the injection molded part 40 at the step of the stepped ejector pin 31, while ensuring the smoothness and reliability of the ejection action.

[0050] like Figure 2 , Figure 3 and Figure 6 As shown, preferably, the top surface of the ejector panel 24 is provided with a limiting block 21; when the ejector mechanism 20 ejects upward to the maximum displacement, the limiting block 21 abuts against the lower end surface of the rear template 10 to limit the maximum relative displacement between the ejector panel 24 and the rear template 10; the depth of the countersunk hole of the ejector panel 24 and the limiting position of the rear template 10 together limit the maximum downward movement of the auxiliary rod 36 to ensure that the rotation angle of the seesaw 34 is within a safe range.

[0051] Specifically, a limiting block 21 is provided on the upper surface of the ejector panel 24. Its function is to form a rigid abutment with the lower end surface of the rear template 10 when the ejector mechanism 20 moves upward to its maximum displacement. This design can precisely limit the maximum relative displacement between the ejector panel 24 and the rear template 10, and prevent the seesaw 34 from rotating too much or the composite ejector pin 32 from becoming unstable due to overtravel of the ejector mechanism 20. This structurally ensures the operational safety of the ejector mechanism 20.

[0052] Meanwhile, the countersunk hole depth of the ejector panel 24 and the limiting position of the rear template 10 work together: the countersunk hole depth determines the movable space of the composite ejector pin 32, while the limiting position of the rear template 10 indirectly limits the maximum downward movement of the auxiliary rod 36 by limiting the maximum upward movement of the ejector panel 24. The combined effect of the two can strictly control the rotation range of the seesaw 34, ensuring that it is always within the safe range of mechanical strength and motion stability, further improving the reliability and durability of the entire ejection mechanism 20.

[0053] like Figure 1 , Figure 4 and Figure 6 As shown, preferably, the bottom of the seesaw 34 is provided with a limiting plane 35 near the end of the composite ejector pin 32; in the initial state of injection molding after mold closing, the bottom of the composite ejector pin 32 abuts against one end of the seesaw 34, causing the seesaw 34 to tilt towards the auxiliary rod 36 and drive the auxiliary rod 36 to remain in an upward-push state, and the limiting plane 35 forms a limiting abutment with the bottom of the accommodating space 23, restricting the seesaw 34 from continuing to rotate towards the auxiliary rod 36, so as to ensure that the top of the composite ejector pin 32 remains in the injection cavity.

[0054] Specifically, a limiting plane 35 is machined at the bottom of the seesaw 34 near the composite ejector pin 32. This plane is the core structure that ensures the stability of the initial state of injection molding.

[0055] In the initial state after mold closing and before injection molding begins, the bottom of the composite ejector pin 32 is in contact with one end of the seesaw 34. Under the action of the restoring force (such as the pre-compression force of the composite spring 33), the pre-compression force pushes the limiting head of the composite ejector pin 32 downward, causing the bottom end of the composite ejector pin 32 to press down against one end of the seesaw 34, thereby pushing the seesaw 34 to tilt towards the auxiliary rod 36, which in turn drives the auxiliary rod 36 to lift upward and maintain its initial position. At this time, the limiting plane 35 at the bottom of the seesaw 34 forms a rigid contact with the bottom of the ejector plate 22 receiving space 23. This contact can strictly limit the seesaw 34 from continuing to rotate towards the auxiliary rod 36, thereby fixing the seesaw 34 at the preset initial angle.

[0056] This limiting design ensures that the top of the composite ejector pin 32 is accurately positioned in the injection cavity, preventing the pressure of the high-pressure injection fluid during injection from pushing the composite ejector pin 32 downwards, which could lead to injection failures such as material shortage or deformation in the corresponding part of the injection molded part 40. At the same time, it lays a structural foundation for the accuracy of the subsequent ejection stage.

[0057] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

Claims

1. A secondary ejection mechanism for injection molds based on a seesaw structure, characterized in that, include: An ejection mechanism (20) is assembled on one side of the rear mold. The ejection mechanism (20) is slidably connected to the rear template (10) through a guide device (12) and is reset by a reset rod (13). The ejection mechanism (20) includes a fixed ejection base plate (22) and an ejection panel (24). The ejection base plate (22) drives the ejection panel (24) to be ejected upward under the drive of the injection molding machine ejector rod. The ejector panel (24) is provided with an ejector pin assembly (30), which includes multiple stepped ejector pins (31) and at least one composite ejector pin (32). The composite ejector pin (32) corresponds to the corner position of the injection molded part (40) and is ejected twice through a seesaw mechanism. The seesaw mechanism includes a seesaw (34) rotatably connected to the ejection base plate (22) and a composite ejector pin (32) and an auxiliary rod (36) that abut against its two ends. The composite ejector pin (32) is pushed to eject again at the end of the ejection stage by the downward movement of the auxiliary rod (36).

2. The secondary ejection mechanism for injection molds based on a seesaw structure according to claim 1, characterized in that, The ejector assembly (30) includes two, three or four composite ejector pins (32), and a seesaw (34) and an auxiliary rod (36) that are matched one by one with the composite ejector pins (32). If there are two composite ejector pins (32), they are respectively assembled at the two corner positions corresponding to one diagonal of the injection molded part (40); If there are three composite ejector pins (32), they are respectively assembled at any three corner positions of the injection molded part (40); If there are four composite ejector pins (32), they are respectively assembled at the four corners of the injection molded part (40).

3. The secondary ejection mechanism for injection molds based on a seesaw structure according to claim 1, characterized in that, The lower end of the ejector panel (24) is provided with multiple countersunk holes. Each countersunk hole is divided into a guide section (25) with a small diameter and a receiving section (26) with a large diameter along the axial direction. The lower ends of the auxiliary rod (36) and the composite ejector pin (32) are provided with a limiting head with a diameter larger than the diameter of its own rod body. When the auxiliary rod (36) is inserted into the countersunk hole of the ejector panel (24), its limiting head is received in the receiving section (26) with a large diameter of the countersunk hole, and the rod body is inserted into the guide section (25) with a small diameter of the countersunk hole. When the composite ejector pin (32) is inserted into the countersunk hole of the ejector panel (24), its limiting head is received in the receiving section (26) with a large diameter of the countersunk hole, and the rod body is inserted into the guide section (25) with a small diameter of the countersunk hole.

4. The secondary ejection mechanism for injection molds based on a seesaw structure according to claim 1, characterized in that, The top of the auxiliary rod (36) can make a limiting impact with the rear template (10) at the end of the ejection stroke, and move downward along its axis under the impact to drive the lever movement of the seesaw (34), thereby pushing the composite ejector pin (32) to achieve secondary ejection.

5. The secondary ejection mechanism for an injection mold based on a seesaw structure according to claim 3, characterized in that, A composite spring (33) is provided in the countersunk hole corresponding to the composite ejector pin (32). One end of the composite spring (33) abuts against the ejector panel (24), and the other end abuts against the limiting head of the composite ejector pin (32). During the reset process of the ejector mechanism (20), the composite spring (33) drives the composite ejector pin (32) to move downward to reset, and drives the auxiliary rod (36) to reset upward to the initial position through the reverse rotation of the seesaw (34).

6. The secondary ejection mechanism for an injection mold based on a seesaw structure according to claim 1, characterized in that, The timing sequence of the secondary ejection is as follows: after the ejection mechanism (20) drives the stepped ejector (31) to complete the first ejection stroke, the composite ejector (32) triggers the secondary ejection, so that the composite ejector (32) lags behind the stepped ejector (31) to generate an additional ejection stroke, so as to release the jamming of the injection molded part (40) at the step of the stepped ejector (31).

7. The secondary ejection mechanism for an injection mold based on a seesaw structure according to claim 1, characterized in that, The ejector base plate (22) has a receiving space (23) corresponding to the seesaw (34). The middle part of the seesaw (34) is pivotally connected to the ejector base plate (22) by a pin, and the seesaw (34) moves within the receiving space (23). The two ends of the seesaw (34) abut against the bottom end of the composite ejector pin (32) and the bottom end of the auxiliary rod (36) respectively, and the torque transmission and stroke amplification are realized through the lever principle.

8. The secondary ejection mechanism for an injection mold based on a seesaw structure according to claim 7, characterized in that, The bottom of the seesaw (34) is provided with a limiting plane (35) near the end of the composite ejector pin (32). In the initial state of injection molding after mold closing, the bottom of the composite ejector pin (32) abuts against one end of the seesaw (34), causing the seesaw (34) to tilt towards the auxiliary rod (36) and drive the auxiliary rod (36) to remain in an upward state. The limiting plane (35) forms a limiting abutment with the bottom of the accommodating space (23), restricting the seesaw (34) from continuing to rotate towards the auxiliary rod (36), so as to ensure that the top of the composite ejector pin (32) remains in the injection cavity.

9. The secondary ejection mechanism for an injection mold based on a seesaw structure according to claim 1, characterized in that, The top surface of the ejector panel (24) is provided with a limiting block (21); when the ejector mechanism (20) ejects upward to the maximum displacement, the limiting block (21) abuts against the lower end surface of the rear template (10) to limit the maximum relative displacement between the ejector panel (24) and the rear template (10).

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