Three-color integrated injection mold and method for a key

Abstract

This invention discloses a three-color integrated injection mold and method for button manufacturing. The mold includes a three-color injection molding machine and a set of three-shot molds. The three-shot molds include three different rear molds and one or more front molds. The front molds are mounted on a rotating turntable and located between the injection molding machine and the rear molds. The three-color injection molding machine has three injection units of different colors distributed around its circumference, each corresponding to one of the three rear molds. During operation, the turntable drives the front molds to sequentially close with the first, second, and third rear molds, completing the sequential injection molding of the outer transparent protective layer, the colored marking layer, and the base body layer of the button product. Each layer directly bonds within the mold to form a one-piece product. This invention achieves three-color integrated injection molding of buttons, eliminating the need for subsequent screen printing, spray painting, and other processes, effectively improving production efficiency and product yield, reducing labor costs, and being more environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and more specifically, to a three-color integrated injection mold for buttons and a corresponding injection molding method. Background Technology

[0002] In the production process of game controller buttons, the button surface typically requires different colors or materials for graphics, markings (such as letters and symbols), and protective layers. Traditional production methods often involve first injection molding the substrate, followed by post-processing techniques such as screen printing, laser engraving, or spray painting to achieve the desired color patterns and surface protection. This multi-step production method has the following problems in practical applications: First, the process is complex, resulting in high labor costs; second, repeated clamping and positioning can easily lead to cumulative errors, resulting in poor product consistency and a low yield; third, the inks and paints used in screen printing and spray painting are environmentally unfriendly, increasing environmental pressure.

[0003] To address these issues, the industry has gradually developed multi-color injection molding technology, which involves molding multiple colors or materials on a single injection molding machine. However, for products like game controller buttons, which have a three-layer structure consisting of a transparent protective layer, a colored label layer, and a base body layer, existing technologies still lack a mold structure and process method that can efficiently and stably achieve integrated molding of these three layers. Summary of the Invention

[0004] The present invention aims to provide a three-color integrated injection mold and method for button production, so as to solve the problems of multiple processes, high labor costs, low product yield and poor environmental performance in the prior art.

[0005] To achieve the above objectives, the present invention provides a three-color integrated injection mold for a button, comprising a set of three-shot molds, wherein the three-shot molds include three different rear molds, namely a first rear mold, a second rear mold, and a third rear mold, and one or more front molds; the front molds are mounted on a rotating turntable and located between the injection molding machine and the rear molds; the three-color injection molding machine has three injection units of different colors distributed circumferentially, each corresponding to one of the three different rear molds.

[0006] Furthermore, there is one front mold, and the three-shot mold is composed of the front mold and three different rear molds. The rotation of the turntable drives the front mold to close with the three rear molds in sequence, realizing the sequential injection molding of multi-color materials.

[0007] Furthermore, the turntable drives the front mold to sequentially close with the first rear mold, the second rear mold, and the third rear mold, respectively completing the injection molding of the first, second, and third layers of the button product. The layers are directly combined within the mold to form an integrated structure.

[0008] Furthermore, after the first rear mold and the front mold are closed, a cavity is formed for the outer transparent part of the product, which is used for injection molding the outer transparent protective layer of the button.

[0009] Furthermore, after the second rear mold and the front mold are closed, a cavity is formed for the colored logo or letter portion, which is used for injection molding the pattern or text logo layer on the surface of the button.

[0010] Furthermore, after the third rear mold and the front mold are closed, they form the cavity of the base portion, which is used for injection molding the main structural layer of the button.

[0011] The present invention also provides a three-color integrated injection molding method for a button, using the mold described in any of the above claims, comprising the following steps:

[0012] In the first injection stage, the turntable drives the front mold to rotate to a position opposite to the first rear mold. After the mold is closed, a first cavity is formed between the first rear mold and the front mold. The first plastic material is injected through the corresponding injection unit to form the first layer structure of the button.

[0013] After the first shot is completed, the mold is opened, and the formed first layer structure remains on the front mold;

[0014] In the second injection stage, the turntable drives the front mold along with the first layer structure already formed on it to rotate to a position opposite to the second rear mold. After the mold is closed, a second cavity is formed between the existing first layer structure of the front mold and the second rear mold. The second plastic material is injected through the corresponding injection unit to form the second layer structure of the button, and the second layer structure is directly combined with the first layer structure in the molten state.

[0015] After the second shot is completed, the mold is opened, and the formed two-layer structure remains on the front mold;

[0016] In the third injection stage, the turntable drives the front mold to rotate to a position opposite to the third rear mold. After the mold is closed, a third cavity is formed between the existing two-layer structure of the front mold and the third rear mold. The third plastic material is injected through the corresponding injection unit to form the third layer structure of the button, and the third layer structure is directly combined with the already formed two-layer structure in the mold.

[0017] After the third shot is completed, the mold is opened and the button product, which is formed by one-piece molding of three layers, is taken out.

[0018] Furthermore, the first plastic material is a transparent material, molded into the outer transparent protective layer of the button; the second plastic material is a colored material, molded into the marking layer on the surface of the button; and the third plastic material is the main body material, molded into the main body layer of the button's base.

[0019] Furthermore, the injection temperature, pressure, and holding time for each injection stage are set according to the characteristics of the plastic material used, so that each layer of material maintains a suitable molten state during sequential injection to achieve molecular-level bonding.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] By setting up a set of molds containing three different rear molds and a rotatable turntable structure, the product can be sequentially injection molded with different colors or materials on the same injection molding machine. The layers are directly bonded within the mold without the need for secondary processing.

[0022] It eliminates the need for multiple post-processing steps such as screen printing, laser engraving, and spray painting required in traditional processes, significantly shortens the production cycle, reduces manual operation, effectively avoids errors caused by multiple clamping and positioning, and significantly improves product consistency and yield.

[0023] The number of processes and reliance on manual labor are reduced, thus lowering the overall manufacturing cost. At the same time, since there is no need to use screen printing inks and spray paints, the emission of harmful substances is reduced, meeting the requirements of green and environmentally friendly production.

[0024] The various colored materials are injected sequentially in a molten state and combine with each other to form a strong intermolecular bond. Compared with the adhesion layer formed by post-processing, the bonding strength is higher and the product is more durable. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0026] Figure 1 This is an overall schematic diagram provided for an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the use of the invention in an embodiment.

[0028] Figure 3 This is a schematic diagram of product injection molding provided for an embodiment of the present invention;

[0029] Figure 4 This is a flowchart provided for an embodiment of the present invention.

[0030] The following are the labeling elements in the figure:

[0031] 1. Three-color injection molding machine; 2. Front mold; 3. First rear mold; 4. Second rear mold; 5. Third rear mold; 6. Injection unit; 7. Turntable; 8. Outer layer of product; 81. Product identification; 82. Product base.

[0032] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly, completely, and in detail described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. To make the technical solutions, structural composition, working principle, process control, and beneficial effects of the present invention clearer, more complete, and more fully disclosed, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, ensuring that those skilled in the art can accurately implement the technical solutions based on the content of this specification and achieve a complete process for three-color integrated injection molding of buttons without excessive experimentation.

[0034] Please see Figures 1 to 4 This invention provides a three-color integrated injection mold for a button, mainly comprising a three-color injection molding machine 1 and a set of three-shot molds. The three-color injection molding machine 1 is a multi-station rotary injection molding device with three-shot injection capability, which can be a horizontal or vertical injection molding device. In this embodiment, a horizontal three-color injection molding machine 1 is used. Three injection units 6 are arranged at intervals along the circumference of the three-color injection molding machine 1. The three injection units 6 are evenly distributed at 120° around the central axis of the equipment. Each injection unit 6 is equipped with an independent barrel, screw, heating coil, nozzle and temperature control system, which can independently control the injection speed, injection pressure, holding pressure, melt temperature, screw speed and back pressure, thereby achieving stable injection of plastics of different colors, materials and fluidity. Each injection unit 6 is used to inject plastic materials of different colors. In actual production, the material type and color of each injection unit can be allocated according to product design requirements, button appearance requirements, and structural strength requirements. For example, the first injection unit is used to inject the outer transparent material, the second injection unit is used to inject the colored marking material, and the third injection unit is used to inject the base body material. Each injection unit 6 adopts a precise alignment design with the corresponding rear mold to ensure that the nozzle and the mold gate bushing fit tightly, avoiding defects such as leakage, stringing, and cold material during injection, and ensuring that the molten material enters the cavity smoothly.

[0035] In this embodiment, the three-shot mold consists of three different rear molds and one front mold 2. Of course, in some embodiments, three identical front molds 2 can be used to improve production efficiency. The three rear molds are the first rear mold 3, the second rear mold 4, and the third rear mold 5, and the structures of the three rear molds are designed according to the three-layer molding requirements of the button. The three rear molds are distributed in a circle on the injection molding machine's worktable, and their positions correspond one-to-one with the three injection units 6. The rear molds are fixed to the moving mold fixing plate of the injection molding machine, and are firmly installed and accurately positioned by positioning pins, locking screws, and high-precision pads to ensure that there is no offset, loosening, or misalignment during continuous mold opening and closing. The front mold 2 is mounted on a rotatable turntable 7. The turntable 7 is a high-rigidity, high-precision rotary worktable equipped with a servo motor, reducer, rotary positioning mechanism, braking mechanism, and zero-point positioning system. The rotation angle of the turntable 7 is precisely controllable, and the repeatability of positioning can reach within 0.05mm, which can ensure that the front mold 2 achieves perfect mold closing and alignment every time it rotates to the corresponding rear mold position. The turntable 7 is located between the three-color injection molding machine 1 and the rear mold. It can drive the front mold 2 to rotate sequentially to the position where it is aligned with the first rear mold 3, the second rear mold 4, and the third rear mold 5 for mold closing. The turntable 7 rotates smoothly without impact or vibration, preventing the pre-molded semi-finished products from shifting, deforming, or falling off during rotation. This structural design, with one front mold and three different rear molds, allows the front mold to remain stationary during injection molding, while the rear molds are changed only by rotating the turntable. The front mold 2 always carries the pre-molded semi-finished products for station switching, eliminating the need to remove the semi-finished products, re-clamp, or manually transfer them. This ensures that each layer of the structure can be accurately aligned and firmly joined during molding, fundamentally eliminating the cumulative errors caused by multiple clamping in traditional processes, and significantly improving the consistency of product dimensions and appearance.

[0036] After the first rear mold 3 and the front mold 2 are closed, a cavity is formed between them for molding the outer layer 8 of the product. This cavity corresponds to the outer transparent protective layer of the button, and the shape of the cavity is completely consistent with the outer contour of the button. As the outermost layer of the button, the transparent protective layer plays a role in wear resistance, scratch resistance, fingerprint resistance, and aging resistance, while ensuring that the internal colored markings are clearly visible. After the second rear mold 4 and the front mold 2 are closed, a cavity is formed between them for molding the product markings 81. This cavity corresponds to the colored pattern or letter marking layer on the surface of the button. The marking cavity is finely processed according to the button characters, symbols, and icons. The colored marking layer is directly injection molded inside the transparent layer without the need for screen printing, spraying, or stickers, so there will be no problems such as lettering fading, color fading, blurring, or peeling. After the third rear mold 5 and the front mold 2 are closed, a cavity is formed between them for molding the product base 82. This cavity corresponds to the main structural layer of the button. The main base layer is the supporting structure for the button and needs to have sufficient strength, toughness, and heat resistance. The cavity is equipped with reasonable reinforcing ribs, snap-fit ​​positions, guide pillars, and other structures to ensure the button's assembly accuracy and reliability. The three cavities are sequentially progressive and nested within each other. The front mold 2 serves as the common cavity surface, maintaining the cavity datum unchanged throughout the three mold closing processes. This allows the three-layer structure to be formed sequentially based on the same datum, achieving precise fitting and tight bonding.

[0037] In actual operation, the front mold 2 is first installed on the turntable 7 and locked with positioning rings, guide pins, and screws to ensure no relative displacement between the front mold 2 and the turntable 7. Simultaneously, the first rear mold 3, the second rear mold 4, and the third rear mold 5 are installed at their corresponding positions on the three-color injection molding machine 1. The horizontality, verticality, and mold closing clearance of the rear molds are adjusted to ensure a tight fit between the parting surfaces, no overflow, and no mold misalignment during mold closing. After mold installation, overall alignment and debugging are performed. The rotation origin of the turntable 7, mold opening and closing stroke, injection position, holding pressure position, and ejection position are calibrated through the injection molding machine control system to ensure that the timing of each action is matched and smoothly connected. After starting the three-color injection molding machine 1, the mold is preheated. Mold heating uses an oil temperature controller or a water temperature controller for closed-loop temperature control. The front mold 2 and the three rear molds each have independent temperature control loops. The mold temperature is set according to the molding requirements of different materials. The temperature of the transparent layer mold is slightly higher to ensure fluidity and transparency, while the mold temperature of the marking layer and base layer is moderate to balance appearance and dimensional stability. Once the temperature reaches the injection molding process requirements and the mold temperature stabilizes, the injection molding operation begins. The entire injection molding process is automatically completed by the injection molding machine control system, without the need for frequent manual intervention, thus achieving automated continuous production.

[0038] In the first injection stage, the turntable 7 rotates the front mold 2 to a position opposite to the first rear mold 3. Once in position, the turntable 7 automatically locks to prevent rotation during mold closing. Subsequently, the mold closing system drives the front mold 2 to close with the first rear mold 3. The closing force is rationally set according to the product's projected area to ensure the cavity does not expand or overflow under high injection pressure. After mold closing, the outer layer 8 of the product is formed. At this point, the injection unit 6 corresponding to the first rear mold 3 is activated, and the screw advances forward, stably injecting the outer transparent plastic material into the cavity. The injection process is divided into multi-stage injection: initial low-speed filling avoids jetting and air bubbles; mid-stage rapid filling ensures the cavity is completely filled; and the final stage uses holding pressure to prevent shrinkage and depressions. After holding pressure and cooling, the outer transparent protective layer of the button is formed. The cooling time is set according to the thickness of the transparent layer to ensure complete curing and no deformation upon ejection. After the first injection is completed, the mold is opened, and the front mold 2 separates from the first rear mold 3. The formed outer transparent protective layer remains on the front mold 2 and will not detach with the first rear mold 3, ensuring that the semi-finished product is stably attached when the work station is switched.

[0039] In the second injection stage, the turntable 7 rotates the front mold 2 along with its pre-formed outer transparent protective layer, moving it to a position opposite the second rear mold 4 and locking it in place. The mold closing system then drives the front mold 2 and the second rear mold 4 to close. At this point, the existing outer transparent protective layer on the front mold 2 and the second rear mold 4 together form the cavity of the product identification 81, with uniform cavity gaps and precise positioning. The injection unit 6 corresponding to the second rear mold 4 is activated, injecting colored plastic material into the cavity. The injection pressure and speed are adjusted according to the fineness of the identification; small characters are filled with low-speed, high-pressure filling to ensure the characters are complete and clear. The colored material, in its molten state, directly contacts, permeates, and intertwines with the inner surface of the transparent protective layer, achieving a strong bond, ensuring that the identification layer and the transparent layer are gap-free, do not separate, and do not warp. After the colored identification layer cools and solidifies, the mold is opened, and the semi-finished product with two layers remains on the front mold 2, continuing to move to the next station with the turntable.

[0040] In the third injection stage, turntable 7 rotates again, moving the front mold 2 to a position opposite to the third rear mold 5. After the front mold 2 and the third rear mold 5 are closed, the existing two-layer structure on the front mold 2 and the third rear mold 5 together form the cavity of the product base 82. The injection unit 6 corresponding to the third rear mold 5 is activated, injecting the base body plastic material into the cavity. The injection process uses multi-stage injection and segmented pressure holding, with extended pressure holding time in thick-walled areas to avoid shrinkage and voids. This material is tightly bonded to the already formed two-layer structure within the mold, and the three layers of material fuse together at the molten interface to form an integrated button product with a bonding strength far exceeding that of traditional screen printing and spray painting methods. After the third injection is completed, the mold is opened, and the front mold 2 and the third rear mold 5 separate. At this point, the complete button product can be directly removed from the front mold 2. The removal method can be automated using a robotic arm, achieving unmanned production. The product is made of a single integrated structure consisting of an outer transparent protective layer, a middle colored label layer, and a base body layer. It requires no further post-processing steps such as screen printing, laser engraving, or spray painting. After removal, it can directly proceed to the inspection and packaging stages, significantly shortening the production process.

[0041] In actual production, the process parameters for each injection stage need to be set reasonably according to the characteristics of the selected plastic material. Material selection typically uses a plastic system with good compatibility to ensure interlayer bonding strength. Taking common transparent PC, colored ABS, and main ABS materials as examples, PC material has high transparency, good impact resistance, and is wear-resistant and weather-resistant, making it suitable as a transparent protective layer. ABS material has good flowability, strong colorability, and moderate strength, making it suitable as a labeling layer and base main layer. The injection temperature for the first injection of the transparent layer is generally controlled between 240℃ and 280℃. The barrel temperature is controlled in stages, gradually increasing from the feeding section to the nozzle to prevent material degradation and yellowing. The injection pressure is controlled between 80 and 120 MPa, adjusted appropriately according to the product thickness and flow length ratio. The holding time is approximately 2 to 4 seconds to ensure a smooth transparent layer surface without shrinkage marks. The temperature of the second injection of the colored marking layer can be appropriately reduced to 220℃ to 260℃ to avoid color discoloration or material decomposition caused by high temperatures. The pressure should be controlled at 70 to 100 MPa, focusing on ensuring complete filling of the fine markings, with a holding time of approximately 1 to 3 seconds. The temperature of the third injection of the base body layer is similar to that of the second injection, but the pressure can be slightly higher to ensure effective bonding with the already formed layers and to prevent internal shrinkage cavities. The cooling time is set according to the overall thickness to ensure the product is fully set before ejection. These parameters are not fixed and can be fine-tuned by the operator based on the actual molding effect, material batch number, and ambient temperature to ensure that each layer of material maintains a suitable molten state during sequential injection, thereby achieving good molecular-level bonding. For different material combinations such as PC / PMMA and TPU / ABS, the parameters can also be adjusted according to the same principle, making this invention widely applicable.

[0042] In the above process, since each layer of material is injected sequentially and bonded together in a molten state, a strong intermolecular bond is formed between the layers. The bonding strength is far higher than that of the adhesion layer formed by traditional post-processing. No delamination, cracking, peeling, or discoloration occurs during high and low temperature cycling, damp heat aging, or abrasion resistance testing. This effectively avoids delamination or discoloration during product use, significantly improving the button's lifespan and reliability. Simultaneously, by using the turntable 7 to drive the front mold 2 to sequentially close with the three rear molds, sequential injection molding of the three-layer structure is achieved continuously on a single injection molding machine. The entire production process requires no manual intervention for mold changes or product transfer. From raw material input to finished product removal, the entire process is completed seamlessly, increasing production efficiency several times compared to traditional processes, significantly reducing the defect rate, and greatly improving production efficiency and product consistency.

[0043] This invention, through an integrated injection molding structure and continuous process, completely replaces the traditional multi-step processes of screen printing, spray painting, and laser engraving, solving long-standing industry pain points such as cumbersome processes, high labor costs, significant environmental pollution, and poor product consistency. Simultaneously, the mold structure is compact, the control logic is clear, and maintenance is simple, making it suitable for mass production, standardization, and automation. It can be widely applied to various multi-color, multi-layer button products such as game controller buttons, remote control buttons, home appliance buttons, and automotive buttons, demonstrating significant economic benefits and promotional value.

[0044] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0045] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A three-color integrated injection mold for a button, characterized in that, It includes a set of three-shot molds, which include three different rear molds, namely a first rear mold (3), a second rear mold (4) and a third rear mold (5), and one or more front molds (2); the front molds (2) are mounted on a rotating turntable (7) and located between the injection molding machine and the rear molds; the three-color injection molding machine (1) has three injection units (6) of different colors distributed around its circumference, corresponding to the three different rear molds.

2. The three-color integrated injection mold for a button according to claim 1, characterized in that, The front mold (2) is one, and the three-shot mold is composed of the front mold (2) and three different rear molds.

3. The three-color integrated injection mold for a button according to claim 1, characterized in that, The turntable (7) drives the front mold (2) to close with the first rear mold (3), the second rear mold (4), and the third rear mold (5) in sequence, respectively completing the injection molding of the three-layer structure.

4. The three-color integrated injection mold for a button according to claim 1, characterized in that, After the first rear mold (3) and the front mold (2) are molded together, they form the cavity of the outer transparent part.

5. The three-color integrated injection mold for a button according to claim 1, characterized in that, After the second rear mold (4) and the front mold (2) are molded together, a cavity for the colored logo or letter part is formed.

6. The three-color integrated injection mold for a button according to claim 1, characterized in that, The third rear mold (5) and the front mold (2) are combined to form the cavity of the base portion.

7. A three-color integrated injection molding method for a button, characterized in that, Using the mold according to any one of claims 1 to 6, the method includes the following steps: S1: The turntable (7) drives the front mold (2) to rotate to a position opposite to the first rear mold (3). After the mold is closed, a first cavity is formed between the first rear mold (3) and the front mold (2). The first plastic material is injected through the corresponding injection unit (6) to form the first layer structure of the button. S2: After the first injection is completed, the mold is opened, and the formed first layer structure is left on the front mold (2); S3: The turntable (7) drives the front mold (2) and the first layer structure already formed on it to rotate to the position opposite to the second rear mold (4). After the mold is closed, a second cavity is formed between the existing first layer structure of the front mold (2) and the second rear mold (4). The second plastic material is injected through the corresponding injection unit (6) to form the second layer structure of the button, and the second layer structure is directly combined with the first layer structure in the molten state. S4: After the second shot is completed, the mold is opened, and the formed two-layer structure remains on the front mold (2); S5: The turntable (7) drives the front mold (2) to rotate to a position opposite to the third rear mold (5). After the mold is closed, a third cavity is formed between the existing two-layer structure of the front mold (2) and the third rear mold (5). The third plastic material is injected through the corresponding injection unit (6) to form the third layer structure of the button, and the third layer structure is directly combined with the already formed two-layer structure in the mold. S6: After the third injection is completed, open the mold and take out the button product, which is formed by one-piece molding of three layers.

8. The three-color integrated injection molding method for a button according to claim 7, characterized in that, The first plastic material is transparent and is molded into the outer transparent protective layer of the button; the second plastic material is colored and is molded into the marking layer on the surface of the button; the third plastic material is the main body material and is molded into the main body layer of the button's base.

9. The three-color integrated injection molding method for a button according to claim 7, characterized in that, The injection temperature, pressure, and holding time for each injection stage are set according to the characteristics of the plastic material used, so that each layer of material maintains a suitable molten state during sequential injection to achieve molecular-level bonding.

10. A button, characterized in that, It is manufactured using the three-color one-piece injection molding method as described in any one of claims 7 to 9.

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