A mold for increasing the adhesive strength of soft and hard adhesives

Abstract

This utility model discloses a mold for increasing the adhesion between soft and hard rubber, including a fixed mold, a moving mold, a translation base plate, and a male mold. A sliding groove is provided on one side of the translation base plate. The male mold slides and engages with the translation base plate through the sliding groove. A pushing cylinder is fixed at the bottom of the translation base plate in the sliding groove. The output end of the pushing cylinder passes through the side wall of the sliding groove and connects to the male mold. A hard rubber molding cavity is provided between the male mold and the moving mold. A soft rubber molding cavity is provided at the bottom of the hard rubber molding cavity between the male mold and the moving mold. At least two anchoring protrusions are provided at the core edge of the hard rubber molding cavity. By providing a combination design of annular slot protrusions and column grooves at the core edge of the hard rubber molding cavity, a multi-scale, multi-directional mechanical interlocking structure (lateral interlocking + vertical anchor points) is formed on the surface of the hard rubber, so that the soft rubber melt forms a "three-dimensional interlock" with the hard rubber after cooling.

Description

Technical Field

[0001] This utility model belongs to the field of injection molding technology, specifically relating to a mold for increasing the adhesive force of soft and hard plastics. Background Technology

[0002] In the fields of consumer electronics, power tools, and daily necessities, composite products made of soft and hard rubber with good tactile feel and anti-slip and shock-absorbing properties are increasingly widely used, such as tool handles, toothbrush grips, and outer casings for electronic products. These products are generally manufactured using a two-stage injection molding process, which mainly includes two technical routes: die-casting and two-color injection molding.

[0003] Injection molding requires first molding a rigid substrate (usually PC, ABS, PP, etc.), which is then cooled and demolded before being placed into another mold for encapsulation with a softer material (such as TPU, TPE, silicone, etc.). Two-color injection molding, on the other hand, utilizes a dedicated two-color injection molding machine and mold with rotating or translating stations. Within the same production cycle, a rigid plastic part is molded at the first station, and then the mold rotates or moves to the second station for a second injection molding of the softer plastic part directly onto its surface, achieving "one-piece molding." Two-color injection molding is particularly suitable for mass production of handles requiring an outer soft plastic anti-slip sleeve due to its high efficiency, high degree of automation, and reduced contamination from intermediate processes.

[0004] However, regardless of whether it's double injection molding or two-color injection molding, the bonding strength between soft and hard plastic materials remains a core challenge determining product reliability and lifespan. In two-color injection molding, the bonding between soft and hard plastics mainly relies on two mechanisms: one is thermal adhesion in the molten state (diffusion and entanglement between molecular chains), and the other is mechanical interlocking achieved by physical interlocking structures (such as grooves and holes) pre-set on the surface of the hard plastic. However, due to the differences in molecular polarity, surface energy, and melting temperature between soft plastics (such as TPE / TPU) and hard plastics (such as PC / ABS), a "weak boundary layer" is easily formed at the interface during the brief thermal contact time of the second injection molding, resulting in insufficient thermal bonding strength. Common mechanical interlocking designs provide limited anchoring force. When handle-type products are subjected to complex external forces such as gripping, torsion, stretching, and impact for a long time, the soft plastic is prone to local deformation under stress, causing the edge structure to peel off first, followed by the disengagement or failure of the surface interlocking structure inside the soft and hard plastics.

[0005] In summary, this utility model proposes a mold to increase the adhesive force between soft and hard plastics, thereby achieving high-strength bonding of soft and hard plastics (especially handle-type products) and improving the bonding strength and durability of the interface between soft and hard plastics in two-color injection molded parts. Utility Model Content

[0006] To achieve the above objectives, this utility model provides the following technical solution: a mold for increasing the adhesive force of hard and soft rubber, comprising a fixed mold, a moving mold, a translation base plate, and a male mold. A sliding groove is provided on one side of the translation base plate. The male mold slides and engages with the translation base plate via the sliding groove. A pushing cylinder is fixed to the bottom of the translation base plate at the bottom of the sliding groove. The output end of the pushing cylinder passes through the side wall of the sliding groove and connects to the male mold. A hard rubber molding cavity is provided between the male mold and the moving mold. A soft rubber molding cavity is provided at the bottom of the hard rubber molding cavity between the male mold and the moving mold. At least two anchoring protrusion groups are provided at the core edge of the hard rubber molding cavity. Each anchoring protrusion group includes an annular groove protrusion and a column groove, with the column groove located at the center of the annular groove protrusion.

[0007] As a preferred embodiment of this utility model, the annular groove protrusion and the core of the hard plastic molding cavity are an integral structure.

[0008] As a preferred embodiment of this utility model, the cross-sectional shape of the annular groove protrusion is one of a rectangle, a trapezoid, or a dovetail shape.

[0009] As a preferred technical solution of this utility model, the edge of the annular groove protrusion is provided with a chamfer or rounded corner structure.

[0010] As a preferred embodiment of this utility model, the core surface of the hard plastic molding cavity is provided with at least two anchoring protrusions, and the anchoring protrusions have a circular cross-sectional shape.

[0011] Compared with the prior art, the beneficial effects of this utility model are:

[0012] (1) This utility model forms a multi-scale, multi-directional mechanical interlocking structure (lateral interlocking + vertical anchor point) on the surface of the hard rubber by setting a combination design of annular groove protrusion and column groove on the core edge of the hard rubber molding cavity. This allows the soft rubber melt to form a "three-dimensional interlock" with the hard rubber after cooling, which greatly improves the interface bonding force and makes up for the defects of insufficient thermal bonding. For handle products that are subjected to complex external forces such as gripping, twisting, stretching and impact for a long time, it can effectively resist lateral peeling (such as lateral edge displacement of the soft rubber edge when gripping). The vertical anchor point formed by the column groove can resist the pull-out force and avoid the separation of the soft rubber layer when stretching.

[0013] (2) The anchoring protrusions disperse local stress by increasing the contact area, avoiding edge peeling or structural disengagement of the soft rubber due to local deformation, and significantly extending the product's service life. The annular groove protrusions, the column grooves, and the anchoring protrusions are all integrated with the core of the hard rubber molding cavity (e.g., machined), without requiring additional mold complexity or cost. Attached Figure Description

[0014] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0015] Figure 1 This is a cross-sectional view of the present invention;

[0016] Figure 2 This is a schematic diagram of the structure of the hard plastic molding cavity core of this utility model;

[0017] Figure 3 This is a schematic diagram of the anchoring structure of the soft and hard adhesive interface of this utility model;

[0018] In the diagram: 1. Fixed mold; 2. Moving mold; 3. Translation base plate; 4. Male mold; 5. Sliding groove; 6. Push cylinder; 7. Hard plastic molding cavity; 8. Soft plastic molding cavity; 9. Annular groove protrusion; 10. Column groove; 11. Anchoring protruding column; 12. Annular snap-fit ​​structure; 13. Recessed structure. Detailed Implementation

[0019] 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 protection scope of the present utility model. Example

[0020] Please see Figure 1-3 This utility model provides the following technical solution: a mold for increasing the adhesion of soft and hard rubber, including a fixed mold 1, a moving mold 2, a translation base plate 3 and a male mold 4. A sliding groove 5 is provided on one side of the translation base plate 3. The male mold 4 slides and engages with the translation base plate 3 through the sliding groove 5. A push cylinder 6 is fixed at the bottom of the translation base plate 3 in the sliding groove 5. The output end of the push cylinder 6 passes through the side wall of the sliding groove 5 and is connected to the male mold 4. A hard rubber molding cavity 7 is provided between the male mold 4 and the moving mold 2. A soft rubber molding cavity 8 is provided at the bottom of the hard rubber molding cavity 7 between the male mold 4 and the moving mold 2. At least two anchoring protrusion groups are provided at the core edge of the hard rubber molding cavity 7. The anchoring protrusion group includes an annular slot protrusion 9 and a column groove 10. The column groove 10 is located at the center of the annular slot protrusion 9.

[0021] In order to ensure the stability of the core structure and the molding accuracy of the hard plastic molding cavity 7, in this embodiment, as a preferred technical solution of the present invention, the annular groove protrusion 9 and the core of the hard plastic molding cavity 7 are an integral structure.

[0022] In order to enhance the mechanical interlocking performance with the soft rubber by using different cross-sectional shapes, in this embodiment, as a preferred technical solution of the present invention, the cross-sectional shape of the annular groove protrusion 9 is one of rectangle, trapezoid or dovetail.

[0023] In order to reduce stress concentration at the edge of the annular groove protrusion 9 and avoid local cracking caused by sharp structure during hard plastic molding, and at the same time improve the flow and filling properties of soft plastic melt through chamfer / rounded corner design to prevent melt from stagnating at the edge of the protrusion or causing cavitation, in this embodiment, as a preferred technical solution of the present invention, the edge of the annular groove protrusion 9 is provided with a chamfer or rounded corner structure.

[0024] In order to increase the contact area between the soft and hard rubber interfaces and to uniformly disperse the pull stress using a circular structure, thereby further improving the peel resistance and pull resistance of the soft rubber layer, in this embodiment, as a preferred technical solution of the present invention, at least two anchoring protrusions 11 are provided on the core surface of the hard rubber molding cavity 7, and the anchoring protrusions 11 have a circular cross-sectional shape.

[0025] In summary, with the help of the above-mentioned technical solution of this utility model, the specific process of the mold for increasing the adhesive strength of soft and hard adhesives described in this utility model is as follows:

[0026] In the hard plastic molding stage: Initially, with the mold closed, the fixed mold 1, moving mold 2, and male mold 4 are closed, forming a hard plastic molding cavity 7 at the top of the moving mold 2 and male mold 4. After the hard plastic melt (such as PC / ABS) is injected into the hard plastic molding cavity 7, the melt wraps around the anchoring protrusions on the core edge, including annular groove protrusions 9, column grooves 10, and anchoring protrusion columns 11 on the core surface. After the hard plastic cools and solidifies, the surface of the hard plastic part will simultaneously form an annular injection groove corresponding to the annular groove protrusion 9 (i.e., a recessed structure 13 on the hard plastic surface), a column structure corresponding to the column groove 10 (i.e., a protruding column inside the injection groove), and a columnar groove corresponding to the anchoring protrusion column 11 (i.e., a recessed groove or hole on the hard plastic surface).

[0027] Parting and translation stage: After the hard plastic part cools and solidifies, the mold is separated. At this time, the push cylinder 6 at the bottom of the translation base plate 3 is activated, the piston rod is retracted and the male mold 4 is pulled down along the sliding groove 5, and the hard plastic part is transferred from the hard plastic molding cavity 7 to the corresponding position of the soft plastic molding cavity 8, completing the station switch of the two-color injection molding.

[0028] In the soft rubber molding stage: After the male mold 4 is moved into place, the mold closes again, and the soft rubber melt (such as TPE / TPU) is injected into the soft rubber molding cavity 8. When the soft rubber melt flows on the surface of the hard rubber part, it will fully fill the annular injection groove, column structure gap and column groove on the surface of the hard rubber. After the soft rubber melt in the annular injection groove cools, it forms an annular snap-fit ​​structure 12 that matches the annular snap-fit ​​protrusion 9, which provides lateral constraint on the edge of the soft rubber layer and effectively prevents the soft rubber from peeling off the side edge due to external forces such as gripping and twisting. After the soft rubber melt around the column structure cools, it forms a "ring" type vertical anchor point that wraps around the column, which can resist the pull-out force generated when the soft rubber layer is stretched or impacted. After the soft rubber melt in the column groove cools, it forms a column protrusion, which further increases the contact area and interlocking depth of the soft and hard rubber interface.

[0029] Finally, it should be noted that, in this utility model, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0030] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A mold for increasing the adhesion of soft and hard rubber, comprising a fixed mold (1), a movable mold (2), a translation base (3) and a male mold (4), characterized in that: The translation base plate (3) has a sliding groove (5) on one side. The male mold (4) slides and engages with the translation base plate (3) through the sliding groove (5). The translation base plate (3) is fixed with a push cylinder (6) at the bottom of the sliding groove (5). The output end of the push cylinder (6) passes through the side wall of the sliding groove (5) and connects to the male mold (4). A hard plastic molding cavity (7) is provided between the male mold (4) and the moving mold (2). A soft plastic molding cavity (8) is provided at the bottom of the hard plastic molding cavity (7) between the male mold (4) and the moving mold (2). At least two anchoring protrusion groups are provided at the core edge of the hard plastic molding cavity (7). The anchoring protrusion group includes an annular slot protrusion (9) and a column groove (10). The column groove (10) is located at the center of the annular slot protrusion (9).

2. The mold for increasing the adhesive strength of soft and hard adhesives according to claim 1, characterized in that: The annular groove protrusion (9) and the core of the hard plastic molding cavity (7) are an integral structure.

3. The mold for increasing the adhesion of soft and hard rubber according to claim 2, wherein: The cross-sectional shape of the annular groove protrusion (9) is one of rectangle, trapezoid or dovetail.

4. The mold for increasing the adhesion of soft and hard rubber according to claim 3, wherein: The edge of the annular groove protrusion (9) is provided with a chamfer or rounded corner structure.

5. The mold for increasing the adhesion of soft and hard rubber according to claim 1, wherein: The core surface of the hard plastic molding cavity (7) is provided with at least two anchoring protrusions (11), and the anchoring protrusions (11) have a circular cross-sectional shape.

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