Manufacturing method of scissor foot key structure

Abstract

According to the manufacturing method of the scissor foot key structure, the inner scissor foot and the outer scissor foot are integrally formed through double-shot molding, so that the inner scissor foot and the outer scissor foot do not need to be assembled, the fit clearance is small, and the shaking degree is low. The method comprises the following specific steps: step S1, firstly, carrying out injection molding on a one-color scissor foot through a one-color front mold; s2, after injection molding of the one-color scissor foot is completed, the one-color front mold is separated from the rear mold, and the one-color scissor foot is kept on the rear mold; s3, the rear mold is switched to a two-color injection molding position, after the one-color scissor foot is shrunk, the two-color front mold and the rear mold are combined and matched with the one-color scissor foot to conduct two-color injection molding, and the two-color scissor foot is formed on the one-color scissor foot in an injection molding mode; step S4, further obtaining an integrally formed scissor foot key structure; wherein the first-color scissor foot and the second-color scissor foot are made of different materials, and the material shrinkage rate of the first-color scissor foot is smaller than or equal to the material shrinkage rate of the second-color scissor foot. The key manufacturing method is applied to the technical field of key manufacturing.

Description

Technical Field

[0001] The present invention is applied to the technical field of key manufacturing, and particularly relates to a method for manufacturing a scissor-leg key structure. Background Art

[0002] With the continuous development of information technology, keyboards have become a classic input device for products such as computers, laptops, tablets, and mobile phones. Laptops, in particular, primarily utilize a scissor-key structure to meet their lightweight and portable requirements. Scissor-key keyboard keys typically feature an inner and outer scissor foot. These two parts are produced separately using an injection molding machine. After production, they are assembled into a scissor foot assembly, either manually or through automated equipment. This assembly is then combined with other components, such as keycaps and conductive films, to create a scissor-key keyboard.

[0003] Among them, the assembly of the inner scissor legs and the outer scissor legs is usually achieved through the cooperation of the hole and the shaft. The hole and the shaft are affected by the cooperation clearance, mold tolerance, injection molding tolerance, etc. The cooperation clearance between the traditional outer scissor legs and the inner scissor legs shaft is usually: 0.02mm~0.08mm. This cooperation clearance is relatively large for the scissor leg buttons, which provides space for shaking, making the two scissor legs shake more and feel worse. At the same time, manpower needs to be allocated for assembly.

[0004] To this end, if a scissor foot key structure manufacturing method and a scissor foot key structure can be provided, in which the inner scissor foot and the outer scissor foot are integrally molded through two-color injection molding, so that the inner scissor foot and the outer scissor foot do not need to be assembled, the fitting clearance is small, and the shaking degree is low, it can provide users with a better key feel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a method for manufacturing a scissor foot button structure in which the inner scissor foot and the outer scissor foot are integrally formed by two-color injection molding, so that the inner scissor foot and the outer scissor foot do not need to be assembled, the fitting clearance is small, and the shaking degree is low.

[0006] The technical solution adopted by the present invention is: the present invention includes the following specific steps: Step S1: First, a single-color front mold and a single-color back mold are used to perform injection molding of a single-color scissor leg. Step S2: After the injection molding of the single-color scissor legs is completed, the single-color front mold is separated from the rear mold, and the single-color scissor legs remain on the rear mold; Step S3: Switch the rear mold to the two-color injection molding position. After the one-color scissor leg has completed shrinkage, close the two-color front mold and rear mold and perform two-color injection molding with the one-color scissor leg, so that the two-color scissor leg is injection-molded on the one-color scissor leg. Step S4, obtaining an integrally formed scissor-shaped key structure; The single-color scissor legs and the two-color scissor legs are made of different materials, and the material shrinkage rate of the single-color scissor legs is less than or equal to the material shrinkage rate of the two-color scissor legs.

[0007] As can be seen from the above scheme, the scissor leg structure can be injection molded in the same workstation by adopting the two-color injection molding method. By using different materials and taking advantage of the different characteristics of the material molecular structure, the two materials will not be completely bonded together after the two injection moldings. At the same time, the shrinkage rate of the one-color scissor leg is less than or equal to the shrinkage rate of the two-color scissor leg, so that the shrinkage of the one-color injection molding is smaller, while the shrinkage of the two-color injection molding is greater than that of the one-color injection molding. Then, due to the difference in shrinkage rate, a small gap is formed at the matching part of the rotating shaft of the one-color scissor leg and the two-color scissor leg, ensuring that the one-color scissor leg and the two-color scissor leg can rotate smoothly, and the method of shrinkage to form the matching gap can make the matching gap as small as possible after the injection molding is completed, reducing the shaking degree of the internal and external scissor leg structures, while ensuring their connectivity and smooth rotation, thereby achieving a better feel. The use of two-color injection molding to complete the manufacture of the internal and external scissor legs does not require subsequent manual or automated assembly, reducing production time, improving production efficiency, and saving assembly costs.

[0008] A preferred solution is that the deformation temperature of the single-color scissor legs is higher than the injection molding temperature of the two-color scissor legs.

[0009] A preferred solution is that the one-color scissor legs are outer scissor legs, and the two-color scissor legs are inner scissor legs.

[0010] A preferred solution is that the material of the single-color scissor legs is polycarbonate or polyamide glass fiber composite material.

[0011] A preferred solution is that the material of the two-color scissor legs is polyoxymethylene or a terpolymer of acrylonitrile, butadiene and styrene.

[0012] A preferred solution is that a gap G is provided between the inner edge of the one-color scissor leg and the outer edge of the two-color scissor leg, and the gap G is greater than or equal to 0.3 mm.

[0013] A preferred solution is that bosses that cooperate with the single-color scissor legs are provided on both sides of the two-color scissor legs, and connecting shafts are provided on the bosses. The single-color scissor legs are correspondingly provided with connecting holes that adapt to the connecting shafts.

[0014] A preferred solution is that the connecting shaft is conical or frustum-shaped.

[0015] A preferred embodiment is that the present invention further includes the following specific steps: a single-color scissor foot cavity and a two-color scissor foot cavity are provided on the rear mold in step S1, the single-color scissor foot cavity and the two-color scissor foot cavity are connected via a molding groove adapted to the boss, the single-color front mold is provided with a front mold inclined top that cooperates with the molding groove seal, and when single-color injection molding is performed, the single-color scissor foot cavity, the single-color front mold and the front mold inclined top cooperate to form a single-color molding cavity.

[0016] A preferred embodiment is that the present invention further includes the following specific steps: the two-color front mold, the two-color scissor-foot cavity, the molding groove and the one-color product in step S3 cooperate to form a two-color molding cavity, and when performing two-color injection molding, the material of the two-color product passes through the molding groove and the surface structure of the one-color product to form the connecting shaft and the boss. The material of the two-color product is different in molecular structure, so that the surface of the connecting shaft and the boss is fitted with the one-color product but not completely bonded. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the exploded structure of the scissor-foot key structure of the present invention; Figure 2 This is a schematic structural diagram of the scissor-foot key structure of the present invention; Figure 3 It is a schematic diagram of the exploded structure of the single-color front mold and rear mold of the present invention; Figure 4 It is a schematic cross-sectional structure diagram of a single-color front mold and a rear mold of the present invention; Figure 5 It is a schematic diagram of the exploded structure of the two-color front mold and the rear mold of the present invention. DETAILED DESCRIPTION

[0018] like Figures 1 to 5 As shown, in this embodiment, the present invention includes the following specific steps: Step S1: First, a single-color scissor foot cavity is formed by cooperating with a single-color front mold 1 and a back mold 2, and a single-color scissor foot 3 is formed by injection molding the single-color scissor foot cavity; Step S2: After the injection molding of the single-color scissor legs 3 is completed, the single-color front mold 1 is separated from the rear mold 2, and the single-color scissor legs 3 remain on the rear mold 2. The rear mold 2 switches positions under the driving action of the moving mechanism; Step S3: The rear mold 2 is rotated 180 degrees and switched to the two-color injection molding position. After the one-color scissor leg 3 has completed shrinkage, the two-color front mold 4 is molded together with the rear mold 2 and cooperates with the one-color scissor leg 3 to form a two-color scissor leg cavity. The two-color scissor leg cavity is subjected to two-color injection molding, thereby injecting the two-color scissor leg 5 onto the one-color scissor leg 3. Step S4: obtaining an integrally formed scissor foot key structure, and after demolding, rotating the one-color scissor foot 3 and the two-color scissor foot 5 to completely separate their injection-molded contact surfaces, thereby obtaining a smaller wobble, a better connection and a better key feel; Among them, the one-color scissor foot 3 is the outer scissor foot, and the two-color scissor foot 5 is the inner scissor foot; the one-color scissor foot 3 and the two-color scissor foot 5 are made of different materials, and the molecular structures of different materials are different. After two injection moldings, the two materials will not be completely bonded together, so that the inner scissor foot and the outer scissor foot can achieve relative movement; at the same time, the deformation temperature of the one-color scissor foot 3 is higher than the injection molding temperature of the material of the two-color scissor foot 5, that is, the high temperature resistance of the one-color scissor foot 3 is higher than that of the two-color scissor foot 5, thereby avoiding the melting and deformation of the material of the one-color scissor foot 3 during two-color injection molding; and in the process of two-color injection molding, the glue in front will produce a layer of oxide film on the surface due to the oxidation effect of oxygen in the mold, and the glue at the front end is easy to cool first during the process of molding, producing a layer of crystallization film. The existence of the oxide film and the crystallization film causes stratification between the one-color injection molding and the two-color injection molding, and the stratification phenomenon can avoid the one-color injection molding and the two-color injection molding from fusing at the contact surface.

[0019] In this embodiment, the shrinkage rate of the material of the single-color scissor leg 3 is less than or equal to that of the material of the two-color scissor leg 5. The material of the single-color scissor leg 3 is polycarbonate or polyamide glass fiber composite material, both of which have a melt temperature of approximately 300 degrees Celsius and a shrinkage rate of 0.25% to 0.7%. The material of the two-color scissor leg 5 is polyoxymethylene (POM) or a terpolymer of acrylonitrile, butadiene, and styrene. Taking the example of the single-color scissor leg 3 being made of polycarbonate and the two-color scissor leg 5 being made of POM, the shrinkage rate of polycarbonate is approximately 0.6%, while the shrinkage rate of POM is approximately 1.6% with a melt temperature of approximately 190 degrees Celsius. Assuming the maximum diameter of the outer scissor leg connection hole mold design is 0.7mm, and the maximum diameter of the inner scissor leg connection shaft mold design is also 0.7mm, according to shrinkage calculation, the outer scissor leg connection hole size is: 0.7 / (1+0.6%)≈0.696mm; the inner scissor leg connection shaft size is: 0.7 / (1+1.6%)≈0.689mm. The fitting clearance between the outer scissor leg and the inner scissor leg shaft is: 0.696-0.689=0.007mm. The fitting clearance between the traditional outer scissor leg and the inner scissor leg shaft is usually: 0.02mm~0.08mm, which is a larger fitting clearance. Therefore, the solution of the present invention realizes the manufacture of a scissor leg key structure with low wobble, excellent connection mobility and good feel.

[0020] like Figure 2As shown, in this embodiment, a gap G is provided between the inner edge of the single-color scissor leg 3 and the outer edge of the two-color scissor leg 5. This gap G is greater than or equal to 0.3 mm. This gap G separates the outer and inner scissor legs into two independent cavities within the mold. This prevents material from the outer leg from flowing into the inner leg mold cavity during single-color injection molding of the outer leg, while also ensuring smooth rotation of the inner and outer legs.

[0021] like Figure 1 As shown, in this embodiment, the single-color scissor leg 3 is U-shaped or U-shaped, and the two-color scissor leg 5 is assembled inside the outer scissor leg. Bosses 6 are provided on either side of the two-color scissor leg 5 to mate with the single-color scissor leg 3. These bosses 6 are provided with connecting shafts 7, and the single-color scissor leg 3 is provided with corresponding connecting holes 8 that mate with these connecting shafts 7. These connecting shafts 7 are conical or frustum-shaped. The coupling between the connecting shafts 7 and the connecting holes 8 enables the rotation of the single-color scissor leg 3 and the two-color scissor leg 5.

[0022] like Figure 3 and Figure 4 As shown, the present invention also includes the following specific steps: in step S1, the rear mold 2 is provided with a one-color scissor foot cavity and a two-color scissor foot cavity, and the one-color scissor foot cavity is connected to the two-color scissor foot cavity through a molding groove 9 adapted to the boss 6, and the one-color front mold 1 is provided with a front mold inclined top 10 that seals the molding groove 9. When performing one-color injection molding, the front mold inclined top 10 descends and docks with the rear mold 2, and the front mold inclined top 10 is provided with a protrusion that forms the connecting hole 8. The one-color scissor foot cavity, the one-color front mold 1 and the front mold inclined top 10 cooperate to form a one-color molding cavity, and the one-color scissor foot 3 is injected and the connecting hole 8 is formed on the one-color scissor foot 3 through the front mold inclined top 10.

[0023] like Figure 5 As shown, the present invention also includes the following specific steps: in step S3, the two-color front mold 4, the two-color scissor foot cavity, the molding groove 9 and the one-color product cooperate to form a two-color molding cavity, and when performing two-color injection molding, the material of the two-color product passes through the molding groove 9 and the surface structure of the one-color product to form the connecting shaft 7 and the boss 6. The material of the two-color product is different in the molecular structure, so that the surface of the connecting shaft 7 and the boss 6 fits with the one-color product but does not adhere.

[0024] In this embodiment, all contact surfaces of the one-color front mold 1, the back mold 2, and the two-color front mold 4 are mirror-polished. The mirror-polished design of the contact surfaces ensures smooth demoulding of the injection molded product and good surface accuracy.

[0025] In this embodiment, the connecting shaft 7 is located at the end of the two-color injection molding flow channel, thereby reducing the impact of the two-color injection molding pressure and temperature on the mating surface of the single-color scissor leg 3.

[0026] Although the embodiments of the present invention are described with practical solutions, they do not limit the meaning of the present invention. For those skilled in the art, it is obvious to modify the implementation scheme and combine it with other solutions based on this description.

Claims

1. A method for manufacturing a scissor-foot key structure, characterized in that: It includes the following specific steps: Step S1: First, a single-color front mold (1) and a back mold (2) are used to perform injection molding of a single-color scissor leg (3); Step S2: After the injection molding of the single-color scissor legs (3) is completed, the single-color front mold (1) is separated from the rear mold (2), and the single-color scissor legs (3) remain on the rear mold (2); Step S3, the rear mold (2) is switched to the two-color injection molding position, and after the one-color scissor leg (3) has completed shrinkage, the two-color front mold (4) and the rear mold (2) are closed and cooperated with the one-color scissor leg (3) to perform two-color injection molding, so that the two-color scissor leg (5) is injection molded on the one-color scissor leg (3); Step S4, obtaining an integrally formed scissor-shaped key structure; The one-color scissor legs (3) and the two-color scissor legs (5) are made of different materials, and the material shrinkage rate of the one-color scissor legs (3) is less than or equal to the material shrinkage rate of the two-color scissor legs (5).

2. The method for manufacturing a scissor-shaped key structure according to claim 1, wherein: The deformation temperature of the one-color scissor leg (3) is higher than the injection molding temperature of the two-color scissor leg (5).

3. The method for manufacturing a scissor-shaped key structure according to claim 1, wherein: The one-color scissor legs (3) are outer scissor legs, and the two-color scissor legs (5) are inner scissor legs.

4. The method for manufacturing a scissor-shaped key structure according to claim 3, wherein: The material of the single-color scissor legs (3) is polycarbonate or polyamide glass fiber composite material.

5. The method for manufacturing a scissor-shaped key structure according to claim 3, wherein: The material of the two-color scissor legs (5) is polyoxymethylene or a terpolymer of acrylonitrile, butadiene, and styrene.

6. The method for manufacturing a scissor-shaped key structure according to claim 3, wherein: A spacing G is provided between the inner edge of the one-color scissor leg (3) and the outer edge of the two-color scissor leg (5), and the spacing G is greater than or equal to 0.3 mm.

7. The method for manufacturing a scissor-shaped key structure according to claim 3, wherein: Bosses (6) cooperating with the single-color scissor leg (3) are provided on both sides of the two-color scissor leg (5); a connecting shaft (7) is provided on the bosses (6); and a connecting hole (8) adapted to the connecting shaft (7) is correspondingly provided on the single-color scissor leg (3).

8. The method for manufacturing a scissor-shaped key structure according to claim 7, wherein: The connecting shaft (7) is conical or frustum-shaped.

9. The method for manufacturing a scissor-shaped key structure according to claim 7, characterized in that: It also includes the following specific steps: in step S1, the rear mold (2) is provided with a single-color scissor foot cavity and a two-color scissor foot cavity, the single-color scissor foot cavity and the two-color scissor foot cavity are connected through a molding groove (9) adapted to the boss (6), and the single-color front mold (1) is provided with a front mold inclined top (10) that is matched with the molding groove (9) for sealing, and when single-color injection molding is performed, the single-color scissor foot cavity, the single-color front mold (1) and the front mold inclined top (10) cooperate to form a single-color molding cavity.

10. The method for manufacturing a scissor-shaped key structure according to claim 9, characterized in that: It also includes the following specific steps: in step S3, the two-color front mold (4), the two-color scissor-foot cavity, the molding groove (9) and the one-color product cooperate to form a two-color molding cavity, and when performing two-color injection molding, the material of the two-color product passes through the molding groove (9) and the surface structure of the one-color product to form the connecting shaft (7) and the boss (6). The material of the two-color product is different in molecular structure, so that the surface of the connecting shaft (7) and the boss (6) fits with the one-color product but does not adhere to it.

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