Multi-stage ejection device for injection molding of automobile front grille

Abstract

This utility model relates to the field of injection molding demolding technology for automotive front grilles, specifically a multi-stage ejection device for injection molding demolding of automotive front grilles. It includes a moving mold base, an ejection base plate stacked and installed in the ejection mounting area inside the moving mold base, a first-stage ejector plate fitted to the upper surface of the ejection base plate, and a second-stage ejector plate fitted to the upper surface of the first-stage ejector plate. This utility model improves upon the problem of existing automotive front grille injection molding demolding devices being unable to achieve multi-stage ejection. It abandons the traditional single-stage synchronous ejection mode and achieves staged demolding through a purely mechanical structure. It first releases the clamping force between the grille frame and the undercut, then ejects the thin-walled grille bars individually, dispersing demolding stress step by step and avoiding defects such as grille bar tearing, whitening, and deformation of the plastic part. The overall structure is simple and stable, requiring no additional driving components, effectively improving the demolding quality and production yield of the grille plastic part.

Description

Technical Field

[0001] This utility model relates to the field of injection molding demolding technology for automotive front grilles, specifically a multi-stage ejection device for injection molding demolding of automotive front grilles. Background Technology

[0002] In the field of automotive parts injection molding production, automotive front grilles are typical thick-thin-wall composite plastic parts. The outer thick-walled frame and the back inverted structure have a large clamping force, while the middle part is distributed with a large number of fine thin-walled grilles. After molding, demolding is difficult. At present, the industry mostly adopts conventional single-stage ejection structure for injection molding demolding mechanisms for this type of plastic parts. It is the mainstream technical solution in grille injection mold applications and can meet the basic demolding production needs of conventional plastic parts.

[0003] Existing technologies employ an integrated synchronous ejection mode, where all ejection components have the same stroke and lack the ability to adjust the timing stepwise. During demolding, the frame, undercuts, and thin-walled grilles simultaneously bear the same ejection force. The strong clamping force of the thick-walled structure pulls on the fragile thin-walled grilles through the plastic part body, and the demolding stress cannot be released in stages. This leads to frequent molding defects such as grille breakage, surface whitening, and frame deformation, directly reducing the production yield of grille plastic parts and failing to meet the high-quality demolding production requirements of complex automotive front grilles. Therefore, a multi-stage ejection device for injection molding demolding of automotive front grilles is proposed to address the above problems. Utility Model Content

[0004] In order to overcome the shortcomings of the prior art and solve at least one of the technical problems mentioned in the background art, this utility model proposes a multi-stage ejection device for injection molding and demolding of automobile front grilles.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a multi-stage ejection device for injection molding and demolding of automotive front grille, including a moving mold base, an ejection base plate stacked and installed in the ejection mounting area inside the moving mold base, a first-stage ejector plate attached to the upper surface of the ejection base plate, and a second-stage ejector plate attached to the upper surface of the first-stage ejector plate; a through hole is opened through the plate body of the first-stage ejector plate, a grille frame top block is fixedly installed in the through hole of the first-stage ejector plate, a snap-fit ​​angled ejector is fixedly installed in the through hole of the first-stage ejector plate, a dense positioning hole is opened on the plate body of the second-stage ejector plate, a grid strip thin ejector pin is fixedly installed in the positioning hole of the second-stage ejector plate, and a gate ejector pin is fixedly installed in the positioning hole of the second-stage ejector plate; Limiting rods are vertically fixed at the four corners of the ejector base plate. A locking slider is laterally slidably installed on the outer side wall of the first-stage ejector plate. An inclined driving block is fixedly installed on the inner side wall of the moving mold base. An elastic separation component is installed between the opposing surfaces of the first-stage and second-stage ejector plates. A stroke limiting post is vertically fixed on the upper surface of the base plate of the moving mold base. An annular groove is opened in the middle of the limiting rod. A snap-fit ​​groove is opened at the inner end of the locking slider. An inclined guide surface is provided on the outer side of the inclined driving block. The locking slider slides laterally along the inclined guide surface and disengages from the annular groove of the limiting rod. The first-stage ejector plate stops ejecting, and the second-stage ejector plate ejects independently.

[0006] Preferably, the upper end face of the primary ejector plate is provided with spring receiving grooves arranged in a ring, and a return spring is vertically installed inside the spring receiving groove. The upper end of the return spring abuts against the lower end face of the secondary ejector plate to form an elastic separation component.

[0007] Preferably, multiple stroke limiting posts are vertically fixed to the upper end face of the moving mold base plate, with the top of the stroke limiting posts facing the lower plate face of the first-stage ejector plate, and the stroke limiting posts are located on the upward movement path of the first-stage ejector plate.

[0008] Preferably, the outer end of the locking slider is provided with an oblique mating surface, and the inclined guide surface of the inclined driving block is in close contact with the oblique mating surface of the locking slider.

[0009] Preferably, a mating groove is provided at the center of the lower surface of the ejector plate, and the interior of the mating groove abuts against the ejector roller of the injection molding machine.

[0010] Preferably, the fine pins on the secondary pin plate are evenly arranged along the grid bar arrangement direction, and the outer diameter of the top of the fine pin is adapted to the wall thickness at the root of the grid bar.

[0011] The advantages of this utility model are: I. This utility model improves the problem that existing automotive front grille injection molding demolding devices cannot achieve multi-stage ejection by setting a graded locking and unlocking structure and an elastic separation component. It breaks the limitation of traditional devices that can only eject in a single stage at the same time. In traditional demolding mechanisms, all ejection components move synchronously. For the complex structure of the front grille with alternating thick and thin walls and undercuts, the overall force uniformity during demolding is poor, and defects such as whitening and breakage of the grille bars and deformation of the frame are very easy to occur. The overall demolding adaptability is poor.

[0012] II. This utility model adopts a pure mechanical timing control method to achieve two-stage ejection. First, the overall ejection and stress relief of the grille frame and the inverted structure are completed. Then, the secondary ejection and demolding of the thin-walled grille and the gate are completed independently. The clamping stress between the plastic part and the cavity is eliminated step by step. Compared with the traditional single-stage ejection structure, the demolding force of this device is more reasonable, which can effectively avoid the problem of poor demolding of plastic parts. The structure operates stably without the need for additional electro-hydraulic components. It has strong versatility and greatly improves the yield rate of injection molding of automotive front grilles. Attached Figure Description

[0013] 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.

[0014] Figure 1 This is a schematic diagram of the overall device of this utility model; Figure 2 This is a schematic diagram of the secondary ejector plate structure in this utility model; Figure 3 This utility model Figure 1 Enlarged schematic diagram of the structure at point A in the diagram; Figure 4 This utility model Figure 2 Enlarged schematic diagram of the structure at point B in the diagram; Figure 5 This is a schematic diagram of the ejector base plate structure in this utility model.

[0015] In the diagram: 1. Moving mold base; 2. Ejector plate; 3. Secondary ejector plate; 4. Mounting through hole; 5. Grille frame top block; 6. Snap-on angled ejector; 7. Dense positioning holes; 8. Grille fine ejector pins; 9. Sprue ejector pins; 10. Limiting rod; 11. Locking slider; 12. Angled drive block; 13. Elastic separation component; 14. Stroke limiting post; 15. Annular groove; 16. Snap-fit ​​groove; 17. Inclined guide surface; 18. Spring receiving groove; 19. Return spring; 20. Angled mating surface; 21. Butt joint groove; 22. Primary ejector plate. Detailed Implementation

[0016] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0017] The following is in conjunction with the appendix Figure 1 —4 provides further detailed description of this application. This application discloses a multi-stage ejection device for injection molding and demolding of automotive front grilles: Reference Figure 1 - Figure 4 A multi-stage ejection device for injection molding and demolding of automotive front grille includes a moving mold base 1. An ejection mounting area is formed inside the moving mold base 1. An ejection base plate 2, a first-stage ejector plate 22, and a second-stage ejector plate 3 are stacked sequentially from bottom to top within the ejection mounting area. Limiting rods 10 are vertically fixedly connected at the four corners of the ejection base plate 2. The limiting rods 10 pass through the first-stage ejector plate 22. An annular groove 15 is provided in the middle of the limiting rod 10. Several mounting through holes 4 are provided through the first-stage ejector plate 22. Grille frame top blocks 5 and snap-fit ​​angled ejectors 6 are fixedly mounted in the mounting through holes 4. The grille frame top blocks 5 are set to the outer edge of the automotive front grille. The snap-fit ​​angled ejectors 6 are arranged to the position of the back snap-fit ​​of the grille. This device can simultaneously eject the thick-walled outer ring of the grille and the snap-fit ​​structure, avoiding the whitening and cracking defects caused by the snap-fit ​​pulling the plastic part during a single ejection. It is suitable for demolding conditions where the grille frame has high rigidity and strong clamping force after molding.

[0018] Locking sliders 11 are horizontally slidably installed on the outer walls of both sides of the primary ejector plate 22. The inner end of the locking slider 11 is provided with a snap-fit ​​groove 16, which can be engaged and matched with the annular snap-fit ​​groove 15 of the limit rod 10. The outer end of the locking slider 11 is provided with a slanted mating surface 20. The inner side wall of the moving mold base 1 is fixedly provided with a slanted driving block 12. The outer side of the slanted driving block 12 is formed with an inclined guide surface 17. The inclined guide surface 17 and the slanted mating surface 20 of the locking slider 11 are in close contact and sliding fit. The entire locking and unlocking structure relies on pure mechanical slanted transmission to achieve timing switching. There is no need to add external driving components such as oil cylinders and timing controllers, which reduces the mold manufacturing cost. At the same time, it reduces oil leakage and action lag caused by hydraulic pipeline layout, and ensures stable and reliable ejection action during mass injection molding production.

[0019] Multiple spring receiving slots 18 are arranged in a ring on the upper end face of the primary ejector plate 22. A return spring 19 is vertically installed inside each spring receiving slot 18. The upper end of the return spring 19 abuts against the lower end face of the secondary ejector plate 3. The spring receiving slots 18 and the return springs 19 together constitute an elastic separation component 13. The multiple sets of return springs arranged in a ring can disperse the elastic force, preventing the secondary ejector plate 3 from shifting or jamming due to unilateral force, ensuring smooth and unimpeded relative sliding between the two ejector plates. The ejector plate 3 has densely spaced positioning holes 7. The grid strip pins 8 and the gate pins 9 are fixedly installed in the positioning holes. The grid strip pins 8 are evenly arranged along the grid strip arrangement direction. The outer diameter of the top of the grid strip pin 8 is adapted to the wall thickness of the grid strip root. The gate pins 9 are arranged corresponding to the gate position of the product. The densely arranged pins can disperse the ejection force borne by the thin-walled grid strip, and prevent the thin grid strip from breaking or deforming during demolding. The gate pins separate the sprue at the same time, eliminating the need for manual gate trimming.

[0020] The upper surface of the base plate of the moving mold base 1 is vertically fixed with multiple stroke limiting posts 14. The top of the stroke limiting posts 14 is directly opposite the lower surface of the first-stage ejector plate 22 and is located on the upward movement path of the first-stage ejector plate 22. The limiting posts can rigidly limit the maximum ejection stroke of the first-stage ejector plate, accurately separate the two-stage ejection action range, and avoid the first-stage ejector plate from excessively pressing the plastic part upward. A docking groove 21 is provided at the center of the lower surface of the ejector base plate 2. The docking groove 21 is used to abut against the ejector roller of the injection molding machine. The ejector roller of the injection molding machine transmits the ejection force through the groove. The groove structure can limit and position the ejector roller, preventing the ejector roller from deviating and hitting the ejector base plate, causing deformation of the plate surface. The limiting tie rods arranged at the four corners synchronously constrain the horizontal displacement of the three plates. The whole ejection mechanism has high coaxiality and is not prone to wear problems such as ejector pin wear and plate wear due to long-term reciprocating ejection.

[0021] During use, after the injection molding is completed and the mold is opened, the injection molding machine ejector rod extends into the docking groove 21 and pushes the bottom plate 2 upward. At this time, the locking groove 16 of the locking slider 11 clamps the annular groove 15 of the limiting pull rod 10. The bottom plate 2, the first-stage ejector plate 22, and the second-stage ejector plate 3 are locked together and move upward synchronously as a whole. The grid frame top block 5 and the snap-fit ​​angled ejector 6 simultaneously eject the grid frame and the undercut structure. The grid strip thin ejector pin 8 and the gate ejector pin 9 simultaneously push the grid strip and the gate sprue, completing the first-stage synchronous ejection. The synchronous ejection method can first release the clamping force of the thick-walled frame of the outer edge of the grid and the back undercut structure on the mold cavity, disperse the tensile stress on the plastic part in the early stage of demolding, and avoid defects such as deformation, whitening or even cracking of the grid frame and the undercut position. This allows the entire plastic part to smoothly detach from the surface of the cavity, creating a good foundation for the secondary ejection of the thin-walled grid strip.

[0022] The mechanism continues to move upward until the locking slider 11 contacts the inclined drive block 12. The inclined mating surface 20 of the locking slider 11 slides relative to the inclined guide surface 17 of the inclined drive block 12, causing the locking slider 11 to slide laterally outward. The locking groove 16 disengages from the annular groove 15, and the locking relationship between the three is released. The entire unlocking action relies on the inclined sliding to achieve pure mechanical transmission, without the need for additional electrical or hydraulic auxiliary components. The action response is timely and the operation is stable. The locking sliders and inclined drive blocks arranged in pairs on the left and right can complete the separation action synchronously, effectively avoiding the problems of plate tilting and ejector pin jamming caused by single-sided unlocking, and ensuring that the force on each component of the ejection mechanism is always balanced.

[0023] As the ejector base plate 2 continues to move upward, the lower surface of the first-stage ejector plate 22 contacts the stroke limit post 14 and is stopped by the limit. The ejector base plate 2 and the first-stage ejector plate 22 generate relative displacement. After the return spring 19 is compressed, it applies a reverse thrust, pushing the second-stage ejector plate 3 to move independently upward relative to the first-stage ejector plate 22. The thin ejector pins 8 of the grid continue to push the thin-walled grid so that it completely leaves the mold cavity. The gate ejector pin 9 simultaneously cuts off the gate waste, completing the two-stage independent ejection and demolding. The step-by-step ejection mode applies ejection force separately to the fine thin-walled grid, which greatly reduces the tensile load on the slender grid and solves the high-frequency defects in mass production such as grid breakage and bending deformation from the root. At the same time, the gate sprue is cut off simultaneously, reducing the subsequent manual trimming of waste.

[0024] After demolding, the injection molding machine ejector roller retracts downwards, and the ejector base plate 2 moves downwards simultaneously. The return spring 19 rebounds and contracts, pulling the secondary ejector plate 3 back down and fitting with the primary ejector plate 22. During mold closing, the cavity plate squeezes the locking slider 11 and slides inwards. The locking slider 11's snap-fit ​​groove 16 re-engages with the annular snap-fit ​​groove 15 of the limit pull rod 10. All structures are reset to their initial state, waiting for the next round of injection molding and ejection. The four limit pull rods 10 are symmetrically arranged at the four corners, and the multiple evenly distributed annular return springs 19 can ensure uniform elasticity. The inclined drive block 12 and the locking slider 11 are symmetrically paired, and the unlocking action is synchronous and smooth. In actual production, the number and installation position of the grille frame top block 5, snap-fit ​​inclined ejector 6, and grille fine ejector pin 8 can be adaptively adjusted according to the outer dimensions, grille spacing, and undercut points of different car front grilles, adapting to the injection molding production of various grille plastic parts.

[0025] The locking slider 11 is laterally slidably mounted on the side of the first-stage ejector plate. Its inner side has a locking groove 16, which engages with the annular groove on the limit rod, locking each ejector plate as a single unit for synchronous ejection. The inclined drive block 12 is fixed to the inner wall of the moving mold base, and its outer side has an inclined guide surface 17. When the mechanism moves upward to the point where the locking slider 11 contacts the inclined drive block 12, the locking slider 11 slides along the inclined guide surface 17 and moves laterally outward under the action of the inclined thrust. The locking groove 16 disengages from the annular groove, completing the unlocking of each ejector plate and realizing the timing switch of the ejection action. The entire process relies on mechanical transmission without additional drive.

[0026] This invention improves upon the existing automotive front grille injection molding demolding device's inability to achieve multi-stage ejection by adding a graded locking and unlocking structure and an elastic separation component 13. It breaks the structural limitation of traditional ejection devices that can only rely on a single ejector plate for synchronous ejection. Existing similar devices have a uniform overall ejection stroke and cannot perform zoned demolding for the differentiated structure of automotive front grilles. When the plastic part is demolded under synchronous force, the thick-walled frame, the undercut structure, and the thin-walled grille bear the same ejection force. The frame part with a larger clamping force is prone to pulling the thin-walled grille, causing quality defects such as cracking, whitening, and deformation of the plastic part. This device relies on the stacked layout of the ejection base plate 2, the first-stage ejector plate 22, and the second-stage ejector plate 3, combined with the timing control structure formed by the limit pull rod 10 and the locking slider 11, to achieve graded control of the demolding action from the structural source, changing the drawback of the single ejection timing of the traditional device.

[0027] This device achieves two-stage ejection action separation based on mechanical timing unlocking, effectively solving the core problem of stress concentration during synchronous ejection in traditional devices. In traditional demolding devices, all ejection components move synchronously, with no distinction between the action of the grid frame top block and the fine ejector pins. The plastic part is completely separated from the cavity at the moment of demolding, and the back undercut and the fine grid strips bear the demolding pull force simultaneously. This device utilizes the inclined surface cooperation between the inclined surface drive block 12 and the locking slider 11, combined with the stroke constraint of the stroke limit post 14 on the first-stage ejector plate 22, to first release the clamping force of the grid frame and undercut through the first-stage ejection, and then demold the thin-walled grid strips separately through the second-stage ejection, thereby removing the adhesion force between the plastic part and the cavity step by step, greatly reducing the tensile stress on the plastic part as a whole during demolding, and is specifically adapted to the complex molding structure of automotive front grilles with alternating thick and thin walls and undercuts.

[0028] This device achieves independent driving of the secondary ejector plate 3 through the elastic separation component 13, further optimizing the operational stability of multi-stage ejection and making up for the shortcomings of traditional devices that lack an adaptive separation structure. Existing integrated ejection structures lack a plate separation mechanism, making it impossible to adjust the ejection stroke of different areas. The stroke of the slender grid ejector pins is consistent with that of the frame ejector blocks, which can easily cause defects such as grid root penetration and bending. This device relies on the reset spring 19 arranged on the upper end face of the primary ejector plate 22. After the primary ejector plate 22 stops at its limit position, the spring force pushes the secondary ejector plate 3 to move upward independently, allowing the grid pins 8 and the gate ejector pins 9 to obtain additional ejection strokes. This accurately completes the separation of thin-walled structures and gate waste, allowing the ejection strokes of different areas to be flexibly distinguished according to the product structure.

[0029] This device employs a purely mechanical structure to achieve multi-stage ejection, solving the problem of missing multi-stage ejection while improving the overall practicality and versatility of the mold. Existing devices capable of staged ejection mostly use hydraulic and electronic control components, which are costly and prone to malfunctions such as oil leakage and signal delay during injection molding. In contrast, this device relies on the pure mechanical coordination of the limit rod 10, locking slider 11, and stroke limit post 14 to complete the timing switch, eliminating the need for external power components and resulting in a lower failure rate. Furthermore, the placement of the grille frame top block 5, snap-fit ​​angled ejector 6, and grille fine ejector pin 8 can be adjusted according to different grille products. While ensuring the stable realization of multi-stage demolding function, it is suitable for mass production processing of various specifications of automotive front grilles, reducing mold development and subsequent maintenance costs and improving the yield rate of molded plastic parts.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A multi-stage ejection device for injection molding of an automobile front grille, characterized in that: The system includes a moving mold base (1), an ejector base plate (2) is stacked and installed in the ejection mounting area inside the moving mold base (1), a first-level ejector plate (22) is attached to the upper plate surface of the ejector base plate (2), and a second-level ejector plate (3) is attached to the upper plate surface of the first-level ejector plate (22); a through hole (4) is opened through the plate body of the first-level ejector plate (22), a grid frame top block (5) is fixedly installed in the through hole of the first-level ejector plate (22), a snap-fit ​​angled top (6) is fixedly installed in the through hole of the first-level ejector plate (22), a dense positioning hole (7) is opened on the plate body of the second-level ejector plate (3), a grid strip thin ejector pin (8) is fixedly installed in the positioning hole of the second-level ejector plate (3), and a gate ejector pin (9) is fixedly installed in the positioning hole of the second-level ejector plate (3); Limiting rods (10) are vertically fixedly connected at the four corners of the ejector base plate (2). Locking sliders (11) are horizontally slidably installed on the outer side wall of the first-stage ejector plate (22). Inclined driving blocks (12) are fixedly installed on the inner side wall of the moving mold base (1). An elastic separation component (13) is installed between the opposite surfaces of the first-stage ejector plate (22) and the second-stage ejector plate (3). An upper surface of the bottom plate of the moving mold base (1) is vertically fixedly provided with... There is a stroke limit post (14); the middle part of the rod body of the limit pull rod (10) is provided with an annular groove (15), the inner end of the locking slider (11) is provided with a snap-fit ​​groove (16), the outer side of the inclined drive block (12) is provided with an inclined guide surface (17), the locking slider (11) slides laterally along the inclined guide surface and disengages from the annular groove (15) of the limit pull rod (10), the first-level ejector plate (22) stops the ejection, and the second-level ejector plate (3) ejects independently.

2. A multi-stage ejector device for injection molding of a front grille of a vehicle according to claim 1, characterized in that: The upper end face of the primary ejector plate (22) is provided with spring receiving grooves (18) arranged in a ring. A return spring (19) is vertically installed inside the spring receiving groove (18). The upper end of the return spring (19) abuts against the lower end face of the secondary ejector plate (3) to form an elastic separation component (13).

3. The multi-stage ejection device for injection molding and demolding of automotive front grilles according to claim 1, characterized in that: Multiple stroke limiting posts (14) are vertically fixed on the upper end face of the base plate of the moving mold base (1). The top of the stroke limiting post (14) is directly opposite the lower plate surface of the first-stage ejector plate (22), and the stroke limiting post (14) is on the upward movement path of the first-stage ejector plate (22).

4. The multi-stage ejection device for injection molding and demolding of automotive front grilles according to claim 1, characterized in that: The outer end of the locking slider (11) is provided with a slanted mating surface (20), and the inclined guide surface (17) of the inclined driving block (12) is in contact with the slanted mating surface (20) of the locking slider (11).

5. A multi-stage ejection device for injection molding and demolding of automotive front grilles according to claim 1, characterized in that: The bottom plate (2) has a docking groove (21) at the center of its lower surface, and the docking groove (21) abuts against the injection molding machine top roller.

6. The multi-stage ejection device for injection molding and demolding of automotive front grilles according to claim 1, characterized in that: The grid pins (8) on the secondary pin plate (3) are evenly arranged along the grid bar arrangement direction, and the outer diameter of the top of the grid pins (8) is adapted to the wall thickness at the root of the grid bar.

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