A plastic part shaping mold

Abstract

The utility model relates to the technical field of plastic processing equipment, and disclose a kind of plastic part sizing die, including upper die and lower die, and the upper die and lower die are all set with cavity for forming, further comprising: setting on the upper die for injection injection port, injection port is mainly composed of feeding section, transition section and discharge section, and three sections are arranged in ladder shape along plastic flow direction;Buffer cavity is set in the upper die for buffering;The utility model is by setting helical flow guide rib in feeding section and cooperating with the injection port structure of ladder type variable diameter, effectively inhibit the generation of turbulent flow, helical flow guide rib guides molten plastic to form spiral propulsion flow, enhances plasticizing uniformity, avoids the cross-sectional flow velocity uneven situation caused by molten plastic linear flow, and ladder type variable diameter solves the eddy problem generated by flow velocity aggravation of equal-diameter straight-cylinder injection port, effectively reduces the local shrinkage mark and warping deformation risk of plastic part after cooling, and further improves processing precision.

Description

Technical Field

[0001] This utility model relates to the field of plastic processing equipment technology, specifically to a plastic part shaping mold. Background Technology

[0002] Injection molding is the core process for mass production of modern plastic products. Its principle is to inject molten plastic material into the mold cavity, and after cooling and solidification, the desired shape of the product is obtained. In this process, the injection gate (or sprue) is the key channel connecting the main runner, branch runner and product cavity of the mold. Its design directly determines the filling speed of molten plastic, flow field pattern, pressure maintenance and the quality of the final product.

[0003] Currently, the injection gate technologies widely used in the industry are mainly divided into two categories: cold runner systems and hot runner systems. Cold runner systems are the traditional form. After each injection cycle, the plastic in the runner and injection gate cools and solidifies along with the product and is discarded as waste. Common cold runner injection gates include direct gates, side gates, point gates, and submarine gates. Hot runner systems, on the other hand, keep the plastic in the runner in a molten state through continuous heating, and only the product in the cavity cools and solidifies, thus avoiding the generation of runner waste.

[0004] In existing technologies, there are certain problems with the injection ports on molds during the injection molding process. For example, in the case of a straight cylindrical structure with a constant diameter, the lack of a gradual transition in the flow channel causes the molten plastic to flow at a higher velocity when entering the cavity, which easily leads to turbulence in the cavity. This results in uneven temperature distribution of the molten plastic in the cavity, and after cooling and solidification, the product is prone to local shrinkage marks or warping deformation, which significantly affects the processing accuracy. On the other hand, some injection ports may cause strong impacts on the inner wall of the cavity during high-speed injection, causing the molten flow front to carry air and resulting in air bubbles in the cavity. Therefore, we urgently need a plastic part forming mold to solve the above problems. Utility Model Content

[0005] This utility model provides a plastic part shaping mold. By using a variable diameter injection port, it solves the problem mentioned in the background art that the flow rate of molten plastic increases when entering the cavity, which easily forms turbulence in the cavity. By setting up a buffer cavity and a diversion hole, it solves the problem mentioned in the background art that the high-speed injection process may cause strong impact on the inner wall of the cavity, resulting in air being trapped at the front of the melt flow and causing bubbles to be generated in the cavity.

[0006] This utility model provides the following technical solution: A molding die for shaping plastic parts includes an upper die and a lower die, both of which have cavities for molding. The die also includes: an injection port on the upper die for injecting liquid, the injection port mainly consisting of an inlet section, a transition section, and an outlet section, arranged in a stepped manner along the direction of plastic flow; and a buffer cavity within the upper die for buffering, the buffer cavity being connected to the outlet section to form a passage, the side of the buffer cavity away from the outlet section being connected to the mold cavity through a diversion hole.

[0007] As a preferred embodiment of this utility model, the cross-section of the buffer cavity is hemispherical, and the radius of the buffer cavity is in the range of 6mm-8mm.

[0008] As a preferred embodiment of this utility model, the number of diversion holes is at least three sets, and the diversion holes are arranged in a fan shape between the cavity and the buffer cavity.

[0009] As a preferred embodiment of this utility model, the cross-section of the diversion hole is trapezoidal, and the angle between its axis and the hypotenuse is in the range of 30°-45°.

[0010] As a preferred technical solution of this utility model, the feeding section is provided with at least three sets of guide ribs along the plastic flow direction. The three sets of guide ribs are spirally arranged and circumferentially distributed on the inner wall of the feeding section.

[0011] As a preferred embodiment of this utility model, the diameter of the feeding section is 8mm-10mm, the diameter of the transition section is 6mm-7mm, and the diameter of the discharge section is 4mm-5mm.

[0012] Compared with the prior art, this utility model provides a plastic part shaping mold, which has the following beneficial effects: 1. In this plastic part forming mold, by setting a spiral guide rib in the feeding section and cooperating with a stepped variable diameter injection port structure, the generation of turbulence is effectively suppressed. The spiral guide rib guides the molten plastic to form a spiral propulsion flow, which enhances the plasticization uniformity and avoids the situation of uneven cross-sectional flow velocity caused by the straight flow of molten plastic. The stepped variable diameter solves the vortex problem caused by the increased flow velocity in the constant diameter straight cylindrical injection port, effectively reducing the risk of local shrinkage and warping deformation of the plastic part after cooling, thereby improving the processing accuracy.

[0013] 2. In this plastic part molding mold, the hemispherical buffer cavity and the fan-shaped trapezoidal diversion holes effectively eliminate the air bubbles caused by the impact on the cavity during high-speed injection. The hemispherical buffer cavity disperses the plastic impact pressure through the arc-shaped inner wall, reducing the impact force on the cavity during injection. The fan-shaped trapezoidal diversion holes can guide the plastic to flow along the inner wall of the cavity, improving the uniformity of injection. They can also squeeze the air in the cavity to the venting groove to be discharged, avoiding the formation of air bubbles, thereby improving the processing accuracy.

[0014] The parts not covered in this device are the same as or can be implemented using existing technologies. This utility model solves the problem of eddy currents caused by increased flow velocity in equal-diameter straight cylindrical injection nozzles, effectively reduces the risk of local shrinkage and warping deformation of plastic parts after cooling, improves the uniformity of injection molding, and can also squeeze the air in the cavity to the exhaust groove to be discharged, avoiding the formation of air bubbles, thereby improving the processing accuracy. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to actual scale.

[0016] Figure 1 This is a schematic diagram of the overall design of this utility model; Figure 2 This is a partial cross-sectional view of the present invention. Figure 1 ; Figure 3 This is a partial cross-sectional view of the present invention. Figure 2 ; Figure 4 This is a partial structural diagram of the present invention.

[0017] In the diagram: 1. Upper mold; 2. Lower mold; 3. Cavity; 4. Injection port; 5. Feed section; 6. Transition section; 7. Discharge section; 8. Buffer cavity; 9. Diverting hole; 10. Guide rib. Detailed Implementation

[0018] 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.

[0019] Example: Reference Figures 1-4A plastic part shaping mold includes an upper mold 1 and a lower mold 2. Both the upper mold 1 and the lower mold 2 are provided with a cavity 3 for molding. Here, the upper mold 1, the lower mold 2 and the cavity 3 for molding are all direct references to existing technical solutions, and will not be described in detail here.

[0020] It also includes an injection port 4 set on the upper mold 1 for liquid injection. The injection port 4 is mainly composed of a feeding section 5, a transition section 6 and an outlet section 7. The three sections are arranged in a stepped manner along the plastic flow direction. The feeding section 5 is provided with at least three sets of guide ribs 10 along the plastic flow direction. The three sets of guide ribs 10 are spirally arranged and circumferentially distributed on the inner wall of the feeding section 5. The diameter range of the feeding section 5 is 8mm-10mm, the diameter range of the transition section 6 is 6mm-7mm, and the diameter range of the outlet section 7 is 4mm-5mm.

[0021] In this embodiment, the injection port 4 is a stepped injection port 4. The diameter of the feeding section 5 is preferably 10 mm and the length is preferably 20 mm. The feeding section 5 directly connects to the injection molding machine nozzle to provide an initial inflow channel for the molten plastic. The diameter of the transition section 6 is preferably 7 mm and the length is preferably 12 mm. It is located between the feeding section 5 and the discharge section 7 and plays a role in buffering and transitioning the flow rate. The diameter of the discharge section 7 is preferably 5 mm and the length is preferably 10 mm. Its end is connected to the buffer chamber 8 to control the flow rate of the plastic entering the buffer chamber 8.

[0022] Furthermore, the guide rib 10 is spirally arranged with a rib height of 0.8 mm and a pitch 1.5 times the length of the feed section 5. For example, when the feed section 5 is 20 mm long, the pitch is 30 mm, and the spiral direction is consistent with the screw rotation direction of the injection molding machine. This spiral guide rib 10 can guide the molten plastic to form a spiral propulsion flow, avoid sudden changes in flow rate, and enhance the plasticization uniformity of the plastic, so that the subsequent molten plastic can smoothly enter the cavity 3.

[0023] Here, the stepped injection port 4, combined with its smooth inter-segment connection, controls the pressure loss, ensures balanced pressure in all areas of the cavity 3, avoids filling defects caused by insufficient pressure, improves the integrity of the plastic part's shaping, and eliminates turbulence during injection by changing the diameter. When turbulence is reduced, the temperature distribution of the plastic melt in the cavity 3 becomes more uniform, reducing the incidence of local shrinkage marks and warping deformation of the plastic part after cooling and shaping, thereby improving processing accuracy.

[0024] A buffer cavity 8 is formed in the upper mold 1 for buffering, and the buffer cavity 8 is connected to the discharge section 7 to form a passage. The side of the buffer cavity 8 away from the discharge section 7 is connected to the cavity 3 through the diversion hole 9. The cross-section of the buffer cavity 8 is hemispherical, and the radius of the buffer cavity 8 is 6mm-8mm. There are at least three sets of diversion holes 9, and the diversion holes 9 are fan-shaped and arranged between the cavity 3 and the buffer cavity 8. The cross-section of the diversion hole 9 is trapezoidal, and the angle between its axis and the inclined side is 30°-45°.

[0025] Here, the buffer cavity 8 has a hemispherical cross-section, preferably with a radius of 8 mm and a corresponding diameter of 16 mm, and an inner wall roughness Ra ≤ 0.8 μm. The hemispherical structure can temporarily store molten plastic, and the plastic flow pressure is dispersed by the arc-shaped inner wall, so that the pressure fluctuation in the cavity is controlled within 0.2 MPa, avoiding direct impact of high-speed plastic on the cavity 3 and reducing the generation of air bubbles.

[0026] Furthermore, the three-part flow holes 9 are arranged in a fan shape to ensure that the plastic is evenly diffused to all areas of the cavity 3. The flow holes 9 are arranged in a trapezoidal shape, and the angle between their axis and the inclined side is preferably 45°, which can further reduce the flow resistance of the plastic, so that the flow rate can smoothly transition from the discharge section 7 to the inside of the cavity 3, avoiding turbulence. At the same time, it guides the plastic to flow along the inner wall of the cavity 3, reduces air entrainment, and effectively solves the problem of bubble generation during injection molding.

[0027] In this invention, when the upper mold 1 and the lower mold 2 are precisely closed by the positioning structure, the cavities 3 on the upper and lower molds are spliced ​​to form a complete and sealed molding space, avoiding plastic leakage during injection molding. When the molten plastic is injected from the injection nozzle into the feeding section 5 of the injection port 4, the molten plastic enters the transition section 6 through the spiral guide rib 10 and then flows to the discharge section 7. The flow rate is stabilized by the stepped diameter change structure. Subsequently, the molten plastic enters the hemispherical buffer cavity 8 from the discharge section 7. After being buffered, the molten plastic enters the cavity 3 through the fan-shaped trapezoidal diversion hole 9, completing the injection molding.

[0028] Components not described in detail in this article are existing technologies.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A molding die for shaping plastic parts, comprising an upper die (1) and a lower die (2), wherein both the upper die (1) and the lower die (2) are provided with cavities (3) for molding, characterized in that, Also includes: An injection port (4) for liquid injection is set on the upper mold (1). The injection port (4) is mainly composed of a feeding section (5), a transition section (6) and a discharge section (7), and the three sections are set in a stepped manner along the plastic flow direction. A buffer cavity (8) is formed in the upper mold (1) for buffering, and the buffer cavity (8) is connected to the discharge section (7) to form a passage. The side of the buffer cavity (8) away from the discharge section (7) is connected to the cavity (3) through the diversion hole (9).

2. The plastic part shaping mold according to claim 1, characterized in that, The cross-section of the buffer cavity (8) is hemispherical, and the radius of the buffer cavity (8) is 6mm-8mm.

3. The plastic part shaping mold according to claim 1, characterized in that, The number of diversion holes (9) is at least three sets, and the diversion holes (9) are arranged in a fan shape between the cavity (3) and the buffer cavity (8).

4. A plastic part shaping mold according to claim 3, characterized in that, The cross-section of the diversion hole (9) is trapezoidal, and the angle between its axis and the hypotenuse is in the range of 30°-45°.

5. A plastic part shaping mold according to claim 1, characterized in that, The feeding section (5) is provided with at least three sets of guide ribs (10) along the plastic flow direction. The three sets of guide ribs (10) are spirally arranged and circumferentially distributed on the inner wall of the feeding section (5).

6. A plastic part shaping mold according to claim 1, characterized in that, The diameter of the feeding section (5) is 8mm-10mm, the diameter of the transition section (6) is 6mm-7mm, and the diameter of the discharge section (7) is 4mm-5mm.

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