An integrated core-pulling and automatic demolding thermoplastic injection mold tooling

Abstract

The application discloses a kind of integrated core-pulling and automatic demolding thermoplastic injection mold tooling, including fixed mould part, movable mould part, side core-pulling mechanism and ejection mechanism.Bidirectional inclined guide pillar is fixed in fixed mould part symmetrically and obliquely, the oblique angle of bidirectional inclined guide pillar is 18°-22°, and the symmetry error is less than 0.03mm;Core-pulling slider is slidably arranged in movable mould part, and core insert for forming inside reverse clamping is installed on its forming end.When the mold is opened, bidirectional inclined guide pillar drives core-pulling slider to move outward horizontally to complete core-pulling, and then ejection mechanism ejects plastic parts, realizing the precise linkage of core-pulling and demolding.The tooling also integrates hot runner system and conformal cooling channel, ensuring uniform melt temperature and improving cooling efficiency.The application solves the problems of complex multi-directional reverse clamping thermoplastic parts demolding difficulty, core seizure and vacuum deformation, eliminates defects such as cold shot mark and flash, realizes efficient automatic production, significantly improves product precision and yield, and reduces mold modification cost and maintenance frequency.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, and more specifically to a tooling for an integrated core-pulling and automatic demolding thermoplastic injection mold. Background Technology

[0002] Traditional molds are complex in structure, cumbersome to assemble and disassemble, and require high-precision machining, making the design, trial molding, and mold repair processes tedious. Furthermore, molds experience thermal expansion and contraction under high temperature and pressure, making it difficult to precisely control the parting surface clearance, resulting in flash on the product. This makes it difficult to meet the machining requirements of high-precision parts and the consistency of mass production, significantly slowing down production progress. In addition, traditional molds typically correspond to only one type of workpiece. When changing the workpiece model or size, the entire mold and tooling must be redesigned and manufactured, resulting in high modification costs and long processing times, making it difficult to handle the flexible production of multiple workpiece varieties.

[0003] In terms of melt delivery, traditional runners mostly use non-heated runner designs, resulting in uneven heating in certain areas and the formation of cold slurry spots. This not only affects the appearance and strength of the molded parts but also wastes raw materials. During the molding process, molds and tooling are prone to defects such as flash, shrinkage marks, and short runs, often requiring multiple mold repairs and adjustments, increasing economic costs. Improper operation can even lead to the scrapping of the entire mold, severely hindering production progress. Furthermore, molds and tooling operate under long-term high-temperature and high-pressure environments, making them susceptible to wear, corrosion, and deformation. Regular disassembly, maintenance, and parts replacement are necessary, further increasing usage and maintenance costs.

[0004] For demolding thermoplastic parts with undercut structures, existing technologies have developed secondary core-pulling mechanisms. For example, Chinese patent CN121821716A discloses a secondary core-pulling injection mold for an automotive center console base. This mold forces the molding block longitudinally away from the undercut by sliding the molding seat along an inclined surface, and then the sliding seat drives the core-pulling rod to pull it out laterally, achieving secondary sequential core pulling and damage-free demolding. Another example is Chinese patent CN116551933A, which discloses a filter seat injection mold. This mold utilizes a hydraulic cylinder and mold opening action to complete the secondary core pulling. During mold closing, the A-plate clamps the large and small sliders to reduce the fitting clearance and solve the problem of severe flash in the product.

[0005] However, the existing core-pulling molds still have significant shortcomings: poor coordination between core-pulling and ejection demolding; for slender, deep cavities or thermoplastic parts with multi-directional internal undercuts, core seizing and breakage due to vacuum adsorption are still prone to occur; the core-pulling direction is relatively singular, making it difficult to simultaneously accommodate one-time demolding of multiple directions such as lateral and oblique undercuts; and none of them integrate hot runners and efficient cooling structures, resulting in poor melt temperature uniformity, unresolved issues of product warping and cold material, high holding pressure, and long molding cycles. Therefore, a compact mold tooling with highly coordinated core-pulling and demolding, capable of adapting to multi-directional undercuts and incorporating cooling and runner optimization, is needed to comprehensively solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a thermoplastic part mold fixture that integrates core pulling and automatic demolding. Through a slanted guide post-linked core pulling and synchronous ejection structure, it achieves stable molding and efficient demolding of complex undercut plastic parts. This solves the problems of poor coordination between core pulling and demolding, easy core seizing, breakage due to the vacuum effect during demolding, and low production efficiency caused by manual intervention in existing thermoplastic part molds when molding complex structural plastic parts.

[0007] The technical solution of the present invention: a tooling for an integrated core-pulling and automatic demolding thermoplastic injection mold, comprising a fixed mold part, a moving mold part, a side core-pulling mechanism and an ejection mechanism; The fixed mold part includes a fixed mold base plate, a cavity plate and a fixed mold plate arranged from top to bottom. A sprue sleeve is fixed on the fixed mold base plate. A sprue sleeve assembly is connected below the sprue sleeve. The sprue sleeve assembly passes through the cavity plate and communicates with the molding cavity. The moving mold part includes a moving template, a moving mold pad fixed below the moving template, a base plate, and a core installed on the moving template. The moving template and the fixed template align with each other to form a molding cavity when the mold is closed. The side core-pulling mechanism includes a set of symmetrical bidirectional inclined guide pillars and a core-pulling slider. The core-pulling slider is symmetrically inclined and fixed inside the cavity plate. The bidirectional inclined guide pillars are slidably disposed inside the moving mold part and have inclined guide holes that cooperate with the bidirectional inclined guide pillars. A core insert is installed on the molding end of the core-pulling slider. The core insert is used to mold the inner undercut of the plastic part. When the mold is opened, the moving mold part retracts, and the bidirectional inclined guide pillars drive the core-pulling slider to move laterally outward to complete the core pulling. The ejection mechanism includes an ejector base plate, an ejector panel, and an ejector pin. The ejector base plate and the ejector panel are stacked one on top of the base plate and the moving mold pad. The ejector pin is fixed on the ejector panel and passes through the moving mold plate and the core in sequence to contact the plastic part. After the core pulling action is completed, the injection molding machine ejector pushes the ejector base plate, which drives the ejector pin to eject the plastic part.

[0008] Furthermore, the inclination angle of the bidirectional inclined guide post is 18° to 22°, the symmetry error of the two inclined guide posts is less than 0.03mm, and the fitting clearance between the inclined guide hole and the bidirectional inclined guide post is 0.01mm to 0.03mm.

[0009] Furthermore, the fixed mold base plate is provided with cooling channels surrounding the sprue bushing assembly, and the cooling channels are arranged along the cavity direction.

[0010] Furthermore, a heating element is provided inside the sprue bushing assembly to form a hot runner system.

[0011] Furthermore, push rods are provided at the four corners of the ejector base plate and ejector panel, and a return spring is sleeved on the outside of the push rod. The upper end of the push rod abuts against the lower surface of the cavity plate to drive the ejection mechanism to accurately reset.

[0012] Furthermore, a positioning ring is provided between the fixed mold base plate and the cavity plate.

[0013] Furthermore, it also includes a side core-pulling slider, which has an oblong hole. One end of the side core-pulling slider is fixed to the positioning ring. Bolts are fixed to the side wall of the cavity plate, and the bolts are slidably fitted in the oblong hole. When the mold is opened, the positioning ring and the cavity plate are separated relative to each other, which drives the side core-pulling slider to pull the core along the direction of the oblong hole.

[0014] Furthermore, guide pillars are fixed on the base plate, and guide sleeves are correspondingly provided on the moving template, moving mold pad, cavity plate, positioning ring and fixed mold base plate. The guide pillars and guide sleeves slide together to ensure mold closing accuracy.

[0015] Furthermore, the moving mold pad and the moving mold plate are fastened together by hexagonal socket screws; the fixed mold base plate and the positioning ring are fixed together by limit screws.

[0016] The beneficial effects of this invention are: 1. High precision and high yield: The 18°~22° tilt angle, <0.03mm symmetry, and 0.01~0.03mm clearance of the bidirectional inclined guide pillars ensure smooth and precise core pulling. The multi-directional core pulling and ejection mechanism are integrated and linked, balancing the demolding force, avoiding workpiece damage, and significantly improving the molding accuracy and yield of complex plastic parts.

[0017] 2. High-efficiency automated production: It achieves seamless connection and fully automatic cycle of core pulling and ejection actions. Combined with conformal cooling channels and hot runner system, it greatly shortens the molding cycle and improves production efficiency.

[0018] 3. Improved quality and material savings: The hot runner system ensures uniform melt temperature, fundamentally eliminating cold slug spots and reducing gate waste. Uniform cooling reduces internal stress and warpage in plastic parts, improving both the internal and external quality of the product.

[0019] 4. Extended tooling life and reduced maintenance costs: Optimized structure and symmetrical layout ensure balanced stress on components, reducing wear and deformation. Integrated reset protection mechanisms (springs, push rods) guarantee stable and reliable operation, extending the mold's lifespan under high temperature and high pressure conditions, and reducing maintenance frequency and costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the thermoplastic injection mold tooling integrating core pulling and automatic demolding according to the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the thermoplastic injection mold tooling integrating core pulling and automatic demolding according to the present invention. Figure 2 ; Figure 3 This invention is an integrated core-pulling and automatic demolding thermoplastic injection mold tooling. Figure 1 ; Figure 4 This invention is an integrated core-pulling and automatic demolding thermoplastic injection mold tooling. Figure 2 ; Figure 5 This is a three-dimensional perspective view of the thermoplastic injection mold tooling that integrates core pulling and automatic demolding according to the present invention; Reference numerals: 1-Base plate; 2-Hex socket screw; 3-Ejector base plate; 4-Ejector face plate; 5-Moving mold plate; 6-Moving mold pad; 7-Ejector pin; 8-Core; 9-Core-pulling slider; 10-Moving mold insert; 11-Two-way inclined guide pillar; 12-Side core-pulling slider; 13-Core insert; 14-Fixed mold plate; 15-Cavity plate; 16-Positioning ring; 17-Fixed mold base plate; 18-Gating bushing; 19-Cooling channel; 20-Bolt; 21-Guide pillar; 22-Guide sleeve; 23-Moving mold base plate; 24-Push rod; 25-Return spring; 26-Guide sleeve with support; 27-Limit screw; 28-Gating bushing assembly. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0023] Example 1: Refer to Figures 1-5 This embodiment provides a thermoplastic injection mold tooling that integrates core pulling and automatic demolding. Its specific structure and the connection relationship of each component are as follows: The fixed mold section consists of, from top to bottom, a fixed mold base plate 17, a cavity plate 15, and a fixed mold plate 14. A sprue bushing 18 is fixed at the center of the fixed mold base plate 17. A sprue bushing assembly 28 is connected below the sprue bushing 18, passing through the cavity plate 15 and extending to the top of the molding cavity. A positioning ring 16 is provided between the cavity plate 15 and the fixed mold base plate 17 for precise alignment and is fixed by a limiting screw 27. Symmetrically inclined bidirectional guide pillars 11 are fixed within the fixed mold plate 14, with an inclination angle of 18°~22°.

[0024] Moving mold section: Located below the fixed mold section, it includes a moving mold plate 5, a moving mold pad 6 fixed under the moving mold plate 5, and a bottom plate 1 at the bottom. A core 8 is installed on the moving mold plate 5, which mates with the fixed mold plate 14 to form a molding cavity. The moving mold pad 6 is fastened to the moving mold plate 5 by hexagonal screws 2. A guide post 21 is fixed on the bottom plate 1. The guide post passes upward through the moving mold plate 5, the moving mold pad 6, the cavity plate 15, the positioning ring 16, and finally to the fixed mold base plate 17. A guide sleeve 22 is fitted on the guide post 21 to ensure the accuracy of mold closing guidance.

[0025] Side core-pulling mechanism includes Main inner core pulling: The core pulling slider 9 is slidably disposed in the moving mold part, and has oblique guide holes that cooperate with the bidirectional oblique guide post 11. The molding end of the core pulling slider 9 is equipped with a core insert 13, which precisely fits the inner undercut of the plastic part.

[0026] Auxiliary outer core pulling: The side core pulling slider 12 has a waist-shaped hole, one end of which is fixed to the positioning ring 16. The bolt 20 on the side wall of the cavity plate 15 slides in the waist-shaped hole to achieve relative sliding core pulling during mold opening.

[0027] Ejection Mechanism: The ejector base plate 3 and ejector face plate 4 are stacked one on top of the other in the space between the base plate 1 and the moving mold pad 6. The bottom of the ejector pin 7 is fixed to the ejector face plate 4, and its rod passes through the moving mold plate 5 and the core in sequence to reach the bottom of the molding cavity. Push rods 24 are installed at the four corners of the ejection mechanism. The push rods are covered with return springs 25. The upper end of the push rod abuts against the lower surface of the cavity plate 15 to achieve precise reset.

[0028] Temperature control and runner system: Cooling channels 19 are provided in the fixed mold base plate 17, surrounding the sprue bushing assembly 28 and arranged along the cavity direction. Heating elements are integrated inside the sprue bushing assembly 28, forming a hot runner system.

[0029] Example 2: This example illustrates the specific working method of the mold tooling described in Example 1 to achieve a complete automated cycle of "mold closing and injection molding → mold opening and core pulling → ejection and demolding → reset and mold closing": Step 1: During the mold closing and injection molding stage, the injection molding machine drives the moving mold part upward, and the upper surface of the moving mold plate 5 fits tightly against the lower surface of the fixed mold plate 14, forming a closed molding cavity. Simultaneously, the guide pillars 21 and guide sleeves 22 ensure precise mold closing. The side core-pulling slider 12 is locked under the mold closing force. The injection molding machine nozzle injects molten plastic into the molding cavity through the sprue bushing 18 and the hot runner sprue bushing assembly 28. Cooling medium is introduced into the cooling channel 19, allowing the molten material to cool and solidify rapidly and uniformly within the cavity.

[0030] Step 2: During the mold opening and core pulling stage, the injection molding machine drives the moving mold part to retract, separating the moving platen 5 from the fixed platen 14. Since the bidirectional inclined guide post 11 is fixed inside the fixed platen 14, it forces the core pulling slider 9, installed in the moving mold part, to move precisely laterally outward through the inclined guide hole, allowing the core insert 13 to be smoothly pulled out from the undercut inside the plastic part. Simultaneously, the cavity plate 15 and the side core pulling slider 12 fixed on the positioning ring 16 slide relative to each other through the oblong hole and bolt 20, completing the auxiliary outer core pulling.

[0031] Step 3: Ejection and demolding stage. After the mold opens to the set distance, the injection molding machine ejector pushes the ejector base plate 3 and ejector plate 4 upward, driving the ejector pin 7 to smoothly eject the plastic part that has completed core pulling from the driven mold core 8, achieving automatic demolding. During the ejection process, the return spring 25 is compressed and stores energy.

[0032] Step 4: Reset and Mold Closure Stage. After the plastic part is removed, the injection molding machine drives the moving mold part to close towards the fixed mold part. Under the elastic force of the return spring 25, the push rod 24 on the ejector plate 3 pushes the entire ejection mechanism to pre-reset. During the mold closing process, the bidirectional inclined guide post 11 drives the core-pulling slider 9 to reset inward, and the side core-pulling slider 12 returns to its original position simultaneously. All components return to their initial state, ready to enter the next injection molding cycle.

[0033] This device solves the problems of automatic demolding of thermoplastic parts with internal undercuts, side holes, and multi-directional undercuts, as well as the breakage and deformation of slender, deep-cavity parts caused by high clamping force, core seizing, and vacuum effects. It overcomes the problems of poor coordination between core pulling and demolding actions in traditional molds, reliance on manual assistance, and long cycle times due to slow cooling. It eliminates defects such as cold slug spots caused by non-heated runners, warping caused by uneven temperature, and flash and shrinkage marks caused by parting line gaps. It breaks the limitations of traditional molds with a single mold opening direction and "one workpiece, one mold," reducing the cost and time required for multi-variety production modifications.

[0034] The above provides a detailed description of the thermoplastic injection mold tooling integrating core pulling and automatic demolding provided by the present invention. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A tooling for an integrated core-pulling and automatic demolding thermoplastic injection mold, characterized in that: It includes the fixed mold section, the moving mold section, the side core-pulling mechanism, and the ejection mechanism; The fixed mold part includes a fixed mold base plate (17), a cavity plate (15) and a fixed mold plate (14) arranged from top to bottom. A sprue sleeve (18) is fixed on the fixed mold base plate (17). A sprue sleeve assembly (28) is connected below the sprue sleeve (18). The sprue sleeve assembly (28) passes through the cavity plate (15) and communicates with the molding cavity. The moving mold part includes a moving template (5), a moving mold pad (6) fixed below the moving template (5), a base plate (1), and a core (8) installed on the moving template (5). The moving template (5) and the fixed template (14) are aligned with each other to form a molding cavity when the mold is closed. The side core-pulling mechanism includes a set of symmetrical bidirectional inclined guide pillars (11) and a core-pulling slider (9). The core-pulling slider (9) is symmetrically inclined and fixed inside the cavity plate (15). The bidirectional inclined guide pillars (11) are slidably disposed in the moving mold part and have inclined guide holes that cooperate with the bidirectional inclined guide pillars (11). The forming end of the core-pulling slider (9) is equipped with a core insert (13). The core insert (13) is used for the inner undercut of the molded plastic part. When the mold is opened, the moving mold part retracts, and the bidirectional inclined guide pillars (11) drive the core-pulling slider (9) to move laterally outward to complete the core-pulling. The ejection mechanism includes an ejector base plate (3), an ejector panel (4), and an ejector pin (7). The ejector base plate (3) and the ejector panel (4) are stacked on top of each other between the base plate (1) and the moving mold pad (6). The ejector pin (7) is fixed on the ejector panel (4) and passes through the moving mold plate (5) and the core (8) in sequence to contact the plastic part. After the core pulling action is completed, the injection molding machine ejector pushes the ejector base plate (3) and drives the ejector pin (7) to eject the plastic part.

2. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: The inclination angle of the bidirectional inclined guide post (11) is 18° to 22°, the symmetry error of the two inclined guide posts is less than 0.03mm, and the fitting gap between the inclined guide hole and the bidirectional inclined guide post (11) is 0.01mm to 0.03mm.

3. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: The fixed mold base plate (17) is provided with a cooling channel (19) surrounding the sprue bushing assembly (28), and the cooling channel (19) is arranged along the cavity direction.

4. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: The gating sleeve assembly (28) is equipped with a heating element to form a hot runner system.

5. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: Push rods (24) are provided at the four corners of the ejector base plate (3) and ejector panel (4). A reset spring (25) is sleeved on the outside of the push rod (24). The upper end of the push rod (24) abuts against the lower surface of the cavity plate (5) to drive the ejection mechanism to reset precisely.

6. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: A positioning ring (16) is provided between the fixed mold base plate (17) and the cavity plate (15).

7. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1 or 6, characterized in that: It also includes a side core-pulling slider (12), which has a waist-shaped hole. One end of the side core-pulling slider (12) is fixed to the positioning ring (16). The side wall of the cavity plate (15) is fixed with a bolt (20), which slides in the waist-shaped hole. When the mold is opened, the positioning ring (16) and the cavity plate (15) are separated, which drives the side core-pulling slider (12) to pull the core along the direction of the waist-shaped hole.

8. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: The base plate (1) is also fixed with guide pillars (21), and guide sleeves (22) are correspondingly provided on the moving template (5), moving mold pad (6), cavity plate (15), positioning ring (16) and fixed mold base plate (17). The guide pillars (21) and guide sleeves (22) slide to ensure mold closing accuracy.

9. The integrated core-pulling and automatic demolding thermoplastic injection mold tooling according to claim 1, characterized in that: The moving mold pad (6) and the moving mold plate (5) are fastened together by hexagonal screws (2); the fixed mold base plate (17) and the positioning ring (16) are fixed together by limiting screws (27).

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