Stepped ejection demolding structure for deep cavity forming

Abstract

The utility model discloses a stepped ejection demolding structure for deep cavity forming, which belongs to the technical field of demolding structures and comprises a workbench, a mounting seat mounted on the workbench, a fixed mold arranged on the mounting seat and a push plate driven by an ejection air cylinder, and movable molds are mounted at telescopic ends of lifting air cylinders mounted on two sides of the mounting seat; the mechanism further comprises a loosening needle set and a force bearing needle set, the ejection action of the loosening needle set is triggered by the initial displacement of the push plate, and a preset gap exists between the force bearing needle set and the push surface of the push plate in the initial state, so that the ejection action of the force bearing needle set is triggered only after the push plate passes through the displacement of the preset gap. A driving assembly is installed on the push plate and used for transmitting the initial displacement of the push plate to the loosening needle set. According to the utility model, the deep cavity adsorption effect can be effectively overcome, and the damage risk of a product at the demolding moment is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field, and in particular to a stepped ejection and demolding structure for deep cavity molding. Background Technology

[0002] In modern molding processes such as injection molding, die casting, or blow molding, the demolding process is a crucial step in removing the molded product from the mold cavity. Currently, the most commonly used demolding structures typically employ a synchronous ejection method, which involves driving a push plate through an ejection mechanism (such as a hydraulic cylinder or pneumatic cylinder), and the push plate simultaneously pushes all the ejector pins to eject the product from the fixed mold or moving mold with a single, direct action.

[0003] However, this traditional synchronous ejection method has significant drawbacks when dealing with products that have deep cavities, thin walls, or high surface finish requirements.

[0004] When the product cools and shrinks inside the mold, a negative pressure area is usually formed between it and the contact surface of the deep cavity, which generates a strong vacuum suction force. In order to overcome this suction force, the ejector pin must apply a very large initial ejection force instantaneously. At the same time, due to the large contact area between the deep cavity product and the mold cavity, the friction force will increase significantly. Under the combined action of the suction force and the friction force, the product needs to apply a very high ejection force in the initial stage of demolding in order to achieve smooth demolding.

[0005] Traditional ejection structures concentrate the maximum ejection force on a few points where the ejector pin contacts the product. This stress concentration can easily cause problems such as stress marks, deformation, and warping in the product. It may even cause the product to be directly punctured or torn by the ejector pin, resulting in a large number of defective products and seriously reducing production efficiency and finished product qualification rate (yield). Utility Model Content

[0006] The purpose of this invention is to effectively overcome the deep cavity adsorption effect and reduce the risk of product damage at the moment of demolding.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a stepped ejection and demolding structure for deep cavity molding, including a worktable, a mounting base installed on the worktable, a fixed mold set on the mounting base, and a push plate driven by an ejection cylinder, wherein a moving mold is installed at the telescopic end of the lifting cylinders installed on both sides of the mounting base.

[0008] It also includes a loosening needle assembly and a supporting needle assembly. The ejection action of the loosening needle assembly is triggered by the initial displacement of the push plate. In the initial state, there is a preset gap between the supporting needle assembly and the push surface of the push plate, so that the ejection action of the supporting needle assembly is triggered only after the push plate has moved through the preset gap. A driving component is installed on the push plate, which is used to transmit the initial displacement of the push plate to the loosening needle assembly.

[0009] As a further description of the above technical solution: the force-bearing pin group includes several force-bearing rods, which slide through the fixed mold and the mounting base, and their bottom ends form a preset gap with the top surface of the push plate.

[0010] As a further description of the above technical solution: the loosening needle assembly includes a plurality of first sleeves installed on the top wall of the inner cavity of the mounting base, the first sleeves having a loosening rod slidably passing through them, the loosening rod slidably passing through the mounting base and the fixed mold, and its top end extending into the inner cavity of the fixed mold.

[0011] As a further description of the above technical solution: a first return spring is sleeved on the loosening rod, and the first return spring is configured to apply a restoring force to the loosening rod to return it to its initial position.

[0012] As a further description of the above technical solution: the driving assembly includes a second sleeve fixed to the bottom wall of the push plate, through which a driving rod slides. The driving rod slides through the push plate, with one end abutting against the bottom end of the loosening rod to transmit the thrust from the push plate.

[0013] As a further description of the above technical solution: a second return spring is sleeved on the drive rod, and the two ends of the second return spring abut against the flange of the drive rod and the wall of the push plate, respectively, for pushing the drive rod to the position abutting against the loosening rod in the initial state.

[0014] As a further description of the above technical solution: when the upward movement of the loosening rod is obstructed, the push plate can compress the second reset spring during the continued upward movement, causing the drive rod to produce a yielding displacement relative to the push plate.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0016] 1. In the first stage, a small pushing force is applied to the edge of the product by a loosening needle assembly with a short stroke and small force. Its main purpose is only to break the vacuum state in the cavity and overcome the initial adhesion force, so that the product and the cavity wall are separated by a small gap. This process avoids applying strong force when the product is under the greatest viscous stress, thus preventing defects such as whitening, deformation or cracking of the product.

[0017] 2. After the product has been initially loosened, the push plate continues to move forward. At this time, since the product is no longer held by the vacuum, the force-bearing pin group can smoothly push the product out of the mold cavity, making the entire demolding process uniform in force and smooth, which greatly improves the success rate of demolding.

[0018] 3. By setting a preset gap between the load-bearing needle assembly and the push plate, and configuring a second return spring for the drive rod that drives the loosening needle assembly, the automatic switching of the two-stage action is realized with a purely mechanical structure. The whole process does not require complex time relays, sensors or independent dual power source control. The structure is simple, compact and low cost. Attached Figure Description

[0019] Figure 1 A front view of the present invention is shown;

[0020] Figure 2 This utility model is shown Figure 1 Enlarged view of point A in the middle.

[0021] Legend:

[0022] 10. Workbench; 11. Mounting base; 12. Fixed mold; 13. Lifting cylinder; 14. Moving mold; 15. Ejection cylinder; 16. Push plate; 17. First sleeve; 18. Loosening rod; 19. First return spring; 20. Second sleeve; 21. Drive rod; 22. Second return spring; 23. Support rod. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] Please see Figures 1-2 This utility model provides a technical solution: a stepped ejection and demolding structure for deep cavity molding, including a worktable 10 and a mounting base 11 fixedly installed on the top surface of the worktable 10. A fixed mold 12 is replaceably installed in the placement groove at the top of the mounting base 11. The fixed mold 12 has a deep cavity for product molding. Lifting cylinders 13 are symmetrically installed on both sides of the mounting base 11. The telescopic end of the lifting cylinder 13 is connected upward and drives the moving mold 14 to lift and lower, so as to realize the opening and closing of the mold with the fixed mold 12.

[0025] In order to achieve phased and low-damage ejection and demolding, an ejection cylinder 15 is installed at the center of the bottom of the inner cavity of the mounting base 11. A push plate 16 is installed vertically upward at the telescopic end of the ejection cylinder 15. The ejection cylinder 15 is the power source for the entire ejection action.

[0026] The stepped ejection function of this device is mainly achieved through two different ejector pin mechanisms and their driving methods, namely the loosening pin group and the bearing pin group.

[0027] Specifically, the loosening pin assembly is used to push the product a short distance during the initial ejection stage to overcome the vacuum suction force. The loosening pin assembly includes several first sleeves 17 distributed around the edge of the cavity, which are vertically fixed to the top wall of the inner cavity of the mounting base 11.

[0028] Each first sleeve 17 has a loosening rod 18 that slides through it. The top of the loosening rod 18 passes through the top wall of the mounting base 11 and further through the fixed mold 12, with its top end extending to the bottom edge of the cavity of the fixed mold 12.

[0029] In order to enable the loosening rod 18 to automatically reset, a first reset spring 19 is provided on its outer ring. The two ends of the first reset spring 19 abut against the flange on the loosening rod 18 and the inner wall of the mounting base 11, respectively, and always provide a downward reset force for the loosening rod 18.

[0030] Furthermore, in order to drive the loosening needle assembly, a drive assembly is installed on the push plate 16. Specifically, the drive assembly includes a second sleeve 20 fixed to the bottom wall of the push plate 16, and a drive rod 21 slides through the second sleeve 20.

[0031] The rod body of the drive rod 21 passes upward through the push plate 16, and its top end abuts against the bottom end of the loosening rod 18 at the corresponding position. In order to achieve stepped drive, a second return spring 22 is sleeved on the outer ring of the drive rod 21. The two ends of the second return spring 22 abut against the flange on the drive rod 21 and the bottom wall of the push plate 16, respectively.

[0032] This structure allows the drive rod 21 to remain at its highest position under normal conditions due to the elastic force of the second return spring 22, but it can retract relative to the push plate 16 when encountering greater resistance.

[0033] The load-bearing pin assembly is used to provide the main ejection force after the product is loosened, so as to completely eject the product. The load-bearing pin assembly includes several load-bearing rods 23. Each load-bearing rod 23 slides through the fixed mold 12 and the mounting base 11, and its top extends to the bottom main load-bearing area of ​​the cavity of the fixed mold 12. Its key feature is that, in the initial state, the bottom end of the load-bearing rod 23 maintains a preset distance from the top surface of the push plate 16.

[0034] Operating procedures:

[0035] Mold closing and molding stage: The lifting cylinder 13 drives the moving mold 14 to descend and close with the fixed mold 12, completing the product injection, pressure holding, cooling and other molding processes. During this stage, the ejector cylinder 15 does not move, the push plate 16 is at the lowest point, and the loosening rod 18 is in the retracted state under the action of the first return spring 19; the drive rod 21 abuts against the loosening rod 18 under the action of the second return spring 22; the bearing rod 23 maintains a preset distance between its bottom end and the push plate 16 due to gravity.

[0036] Loosening stage: After molding is completed, the lifting cylinder 13 drives the moving mold 14 to rise and complete the mold opening. Then, the ejection cylinder 15 starts and drives the push plate 16 to move upward at a constant speed. Since there is a gap between the support rod 23 and the push plate 16, the push plate 16 will not contact the support rod 23 in the initial rising stage. At this time, the push plate 16 pushes the loosening rod 18 upward through the drive rod 21 installed on it. The top of the loosening rod 18 contacts the bottom edge of the product and generates a small ejection force.

[0037] This force is mainly used to overcome the vacuum adsorption effect and slight adhesion between the product and the mold cavity wall, which are common in deep cavity molding. This causes the product to loosen slightly and separate from the cavity wall. The stroke is short and the force is small at this stage, which avoids whitening, deformation or damage to the product edges caused by violent ejection.

[0038] Main ejection stage: After the loosening rod 18 moves upward a short predetermined distance, its own structure will limit its continued rise. At this time, the push plate 16 continues to move upward. Since the loosening rod 18 cannot move, the reaction force on the drive rod 21 increases. The push plate 16 will then overcome the elastic force of the second return spring 22, causing the drive rod 21 to slide downward relative to the push plate 16, i.e., be compressed.

[0039] At the same time, the continuously rising push plate 16 eliminates the gap with the bottom of the support rod 23 and begins to contact and push the support rod 23. At this time, the ejection force is switched from the loosening rod 18 to the support rod 23. The support rod 23 has a larger contact area and a more reasonable distribution, which can provide a strong and stable ejection force to completely eject the loosened product from the deep cavity.

[0040] Reset phase: After the product is removed, the ejector cylinder 15 retracts, driving the push plate 16 to reset downwards. As the push plate 16 descends, the load-bearing rod 23 first falls and resets under its own weight. The loosening rod 18 also resets downwards under the elastic force of its corresponding first reset spring 19. When the loosening rod 18 resets, its reaction force on the drive rod 21 disappears, and the drive rod 21 bounces upwards under the elastic force of the second reset spring 22, returning to the initial ready state of contact with the loosening rod 18.

[0041] At this point, the entire demolding structure is fully reset and ready for the next production cycle.

[0042] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A stepped ejection and demolding structure for deep cavity molding, comprising a worktable (10), a mounting base (11) mounted on the worktable (10), a fixed mold (12) set on the mounting base (11), and a push plate (16) driven by an ejection cylinder (15), wherein a moving mold (14) is mounted on the telescopic ends of lifting cylinders (13) mounted on both sides of the mounting base (11). Its features are: It also includes a loosening needle group and a supporting needle group. The ejection action of the loosening needle group is triggered by the initial displacement of the push plate (16). In the initial state, there is a preset gap between the supporting needle group and the push surface of the push plate (16), so that the ejection action of the supporting needle group is triggered only after the push plate (16) has passed the preset gap displacement. A driving component is installed on the push plate (16), which is used to transmit the initial displacement of the push plate (16) to the loosening needle group.

2. The stepped ejection and demolding structure for deep cavity molding according to claim 1, characterized in that: The load-bearing pin assembly includes several load-bearing rods (23), which slide through the fixed mold (12) and the mounting base (11), and their bottom ends form a preset gap with the top surface of the push plate (16).

3. The stepped ejection and demolding structure for deep cavity molding according to claim 1, characterized in that: The loosening needle assembly includes a plurality of first sleeves (17) installed on the top wall of the inner cavity of the mounting base (11). The first sleeves (17) have a loosening rod (18) slidably passing through them. The loosening rod (18) slidably passes through the mounting base (11) and the fixed mold (12), with its top end extending into the inner cavity of the fixed mold (12).

4. The stepped ejection and demolding structure for deep cavity molding according to claim 3, characterized in that: A first return spring (19) is fitted on the loosening rod (18), and the first return spring (19) is configured to apply a return force to the loosening rod (18) to return it to its initial position.

5. The stepped ejection and demolding structure for deep cavity molding according to claim 3, characterized in that: The drive assembly includes a second sleeve (20) fixed to the bottom wall of the push plate (16), through which a drive rod (21) slides. The drive rod (21) slides through the push plate (16), with one end abutting against the bottom end of the loosening rod (18) to transmit the thrust from the push plate (16).

6. The stepped ejection and demolding structure for deep cavity molding according to claim 5, characterized in that: A second return spring (22) is sleeved on the drive rod (21). The two ends of the second return spring (22) abut against the flange of the drive rod (21) and the wall of the push plate (16) respectively, and are used to push the drive rod (21) to the position where it abuts against the loosening rod (18) in the initial state.

7. The stepped ejection and demolding structure for deep cavity molding according to claim 6, characterized in that: When the upward movement of the loosening rod (18) is obstructed, the push plate (16) can compress the second return spring (22) during the process of continuing to move upward, so that the drive rod (21) produces a yielding displacement relative to the push plate (16).

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