Method for eliminating bump of weld line of injection molded part and injection mold

Abstract

The invention belongs to the technical field of injection molds, and provides an injection molding part weld line bump eliminating method and an injection mold, and the injection molding part weld line bump eliminating method comprises the following steps: arranging a glue reducing layer at a position corresponding to an injection molding part weld line in a cavity of the injection mold; and the injection molding speed is reduced and injection molding is performed to the glue reducing layer, so that the thickness of an injection molding part formed after injection molding of the injection mold at the glue reducing layer is reduced. According to the injection molding part, the glue reducing layer is arranged at the position of the welding line, so that material flow near the welding line can be controlled, the thickness of the injection molding part at the glue reducing layer is reduced compared with that of other parts, the welding line bulge phenomenon caused by material accumulation is relieved to a certain extent, and thus the bulge is eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of injection molds, and in particular relates to a method for eliminating bulging at weld lines of injection molded parts and an injection mold. Background Art

[0002] During the injection molding process of plastic products, glue from two different directions flows together, and the temperature at the front end of the two glues will be slightly lower than the actual sol temperature, which will produce welding marks, which are the weld lines.

[0003] When the molten plastic meets the insert holes, the area with discontinuous flow rate and the area where the filling material flow is interrupted in the cavity, it cannot be completely fused and a linear weld line is generated. In addition, the injection molding at the gate will also generate a weld line, and the strength and other properties of the weld line are very poor.

[0004] In the related technology, in product design with uniform wall thickness, bulging is easy to occur on the weld line after the part is formed, which makes the weld line feel tactile and highly visible. Adding venting to the mold cannot solve this problem, which seriously affects the product quality of the injection molded parts. Summary of the invention

[0005] In view of this, the present invention provides a method for eliminating bulging at a weld line of an injection molded part and an injection mold to solve the problem of bulging at a weld line of an injection molded part existing in the prior art.

[0006] In a first aspect, the present invention provides a method for eliminating bulging at a weld line of an injection molded part, comprising: setting a glue-reducing layer at a position corresponding to the weld line of the injection molded part in a cavity of an injection mold; reducing the injection speed and injecting into the glue-reducing layer, so that the thickness of the injection molded part formed by the injection mold after injection molding at the glue-reducing layer is reduced.

[0007] In an optional embodiment, the thickness of the adhesive reduction layer is 0.3 mm to 1.2 mm.

[0008] In an optional embodiment, the distance between the edge of the adhesive reduction layer and the weld line is 10 mm to 14 mm.

[0009] In an optional embodiment, the rubber-reducing layer is iron added to the movable mold side of the mold.

[0010] In an optional embodiment, the injection molding speed is 12 mm / s to 18 mm / s.

[0011] In an optional embodiment, the injection molding time is 2 seconds to 4 seconds.

[0012] In an optional embodiment, the mold temperature during injection molding is 32°C to 38°C.

[0013] In an optional embodiment, the method for eliminating bulging at the weld line of an injection molded part further includes: determining a glue reduction position of the weld line by mold flow analysis; and providing the glue reduction layer at the glue reduction position.

[0014] The present invention also provides an injection mold, comprising a cavity, wherein a glue reducing layer is provided in the cavity at a position corresponding to the weld line, so as to implement any of the methods for eliminating weld line bulges of injection molded parts described in any one of the above, so that the injection molded parts formed after injection molding eliminate the weld line bulge feel.

[0015] The beneficial effects of the present invention are:

[0016] The present invention can control the material flow near the weld line by arranging a glue-reducing layer at the weld line position, so that the thickness of the injection molded part at the glue-reducing layer is smaller than that of other parts, thereby reducing the oriented accumulation of talcum powder and eliminating bulging. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the following briefly introduces the drawings required for use in the specific implementation or the prior art description. Obviously, the drawings described below are some implementations of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 The present invention is a flowchart of a method for eliminating bulging at a weld line of an injection molded part according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Combine the following Figure 1 , describing an embodiment of the present invention.

[0024] like Figure 1 As shown, according to an embodiment of the invention, a method for eliminating bulging at a weld line of an injection molded part is provided, and the method for eliminating bulging at a weld line of an injection molded part comprises the following steps:

[0025] Step S101: a glue-reducing layer is provided in the cavity of the injection mold at a location corresponding to the weld line of the injection molded part.

[0026] Step S102: reducing the injection speed and performing injection molding to the reduced-glue layer, so that the thickness of the molded part formed by the injection mold after injection molding at the reduced-glue layer is reduced.

[0027] The present invention relates to an improved method for eliminating bulging at the weld line of an injection molded part. In step S101, a glue-reducing layer is carefully designed and arranged in the cavity of the injection mold, especially at the position of the weld line of the injection molded part. The purpose of the setting of the glue-reducing layer is to control the material flow near the weld line in the subsequent injection molding process, thereby creating conditions for eliminating bulging.

[0028] Next, in step S102, the injection speed of the injection molding machine is adjusted to reduce it to a suitable level. Then, the injection molding process is started until the injection material reaches the preset reduced glue layer position. In this way, the thickness of the injection molded part at the reduced glue layer will be reduced compared to other parts, so that not only can the weld line bulging phenomenon caused by material accumulation be alleviated to a certain extent, but also the use of materials can be reduced.

[0029] Furthermore, the thickness of the adhesive reduction layer is 0.3 mm to 1.2 mm.

[0030] In order to achieve better performance and effect, the thickness of the glue-reducing layer is precisely controlled between 0.3 mm and 1.2 mm. This thickness range is obtained through rigorous testing and optimization to ensure that the glue-reducing layer can effectively reduce the amount of material while maintaining the structural strength and durability of the product. The preferred thickness is 1 mm, which eliminates the bulging phenomenon at the weld line.

[0031] Furthermore, the distance between the edge of the reduced adhesive layer and the weld line is 10 mm to 14 mm.

[0032] The edge of the reduced glue layer should be kept at a certain distance from the weld line. The range of this distance should be between 10 mm and 14 mm. The preferred solution is 12 mm, which can ensure that the injection speed of the reduced glue layer can be reduced. Among them, the plastic flow is filled in the form of fountain flow. If the flow fronts from two directions meet, they will stagnate instantly. At this time, the surface layer in contact with the mold wall is frozen, and the orientation direction of the talcum powder at the weld line position changes. In addition, the pressure on both sides of the flow front is uneven, and the material flow flows back between the external frozen layers, and undercurrents will occur at this time. When the flow is reversed, the frozen layer will partially re-melt due to shear heat. By reducing the injection speed, the thickness of the frozen layer of the core layer is increased, the speed at the weld line position is reduced, and the resistance to the displacement of the weld line core layer is increased. The material flow cannot be turned, thereby avoiding the generation of bulges.

[0033] The product has 0.5mm of glue leakage at the weld line and 12mm transition to both sides, which can solve the weld line bulging problem.

[0034] Furthermore, the rubber-reducing layer is iron added to the movable mold side of the mold.

[0035] Add iron material to the active mold side of the mold, and process it into a specific shape and size through welding and iron addition, so as to achieve the setting of the glue reduction layer and realize the local wall thickness reduction of the injection molded part.

[0036] In this embodiment, the temporary measure of reducing the glue layer is made of tin foil, which has a smooth surface and a high melting point, and the plastic cannot be melted. Iron is added to the movable mold side of the mold, and the wall thickness of the product B side is reduced. The subsequent mold is welded and ironed according to the size of the reducing glue layer and processed into a specific size and shape.

[0037] In this embodiment, the injection speed is 12 mm / s to 18 mm / s. The working speed range of the injection molding machine is set between 12 mm / s and 18 mm / s. Such a speed setting can ensure that the injection molding process is both efficient and stable, avoiding uneven material flow caused by too fast a speed or affecting production efficiency due to too slow a speed.

[0038] The time of injection molding is 2 to 4 seconds, preferably 3 seconds. The time of injection molding is usually set between 2 to 4 seconds to ensure that bulges are avoided at the weld line.

[0039] Furthermore, the mold temperature during injection molding is 32° C. to 38° C., preferably 35° C. By increasing the mold temperature, the bonding temperature at the weld line can be increased, thereby improving the fusion quality.

[0040] Optionally, the method for eliminating bulging at the weld line of an injection molded part further comprises the following steps:

[0041] Step S103: determining the glue reduction position of the weld line through mold flow analysis.

[0042] Step S104: setting a glue reduction layer at the glue reduction position.

[0043] First, the mold flow analysis software is used to analyze the injection molded parts in depth to accurately determine the location of the weld line and the amount of rubber that needs to be reduced. In this way, it is possible to clearly indicate which areas should be reduced to reduce weld line bulging.

[0044] After determining the locations for glue reduction, the next step is to set glue reduction layers at these specific locations. This involves adjusting the design of the injection mold to reduce the amount of glue filling in the area where the weld line is located. By setting glue reduction layers in these areas, the pressure and stress concentration at the weld line can be effectively reduced, thereby reducing or eliminating the bulging phenomenon.

[0045] Among them, when conducting mold flow analysis, the mold flow filling time is 2.5 seconds, the holding pressure is 40Mpa, the time is 8 seconds, and the material is PP+20% talcum powder. The main wall thickness of the product is 2.5 mm, and a single-point open hot runner is used to switch to a cold runner for infiltration, and the gate size is 5x1.5 mm. The product is partially reduced in glue, and the result changes of the weld line position of the two wall thicknesses are compared. From the change in average speed, it can be seen that after the local reduction of glue at the weld line position of the product, the filling speed has a significant decrease. Speed ​​reduction is an effective way to improve orientation. From the change in filling speed, it can be seen that when filling quickly, the material flow turns earlier, and when slow filling is used, the material flow still turns. After local reduction of glue, the core layer freeze layer becomes thinner and the material flow cannot turn. The product cannot solve the problem of weld line bulge by optimizing the filling speed, but can only improve it, and there is an obvious undercurrent line at the weld line position of the product. The glue reduction treatment was carried out on site by sticking aluminum foil with a thickness of 1mm. The undercurrent line of the actual product disappeared, and there was no bulge at the weld line position.

[0046] Among them, talc is usually in the form of dense blocks, blades, radials, or fibers. It has a pearly luster or greasy luster. By adopting slow filling and high mold temperature, the shear stress is reduced, and the ridges are eliminated by reducing the orientation of the talc. The best way is to reduce the glue at the weld line by 1mm, increase the thickness of the frozen layer of the core layer, reduce the speed at the weld line, and increase the resistance to the displacement of the weld line core layer.

[0047] The present invention also provides an injection mold, including a cavity, wherein a glue reducing layer is provided at a position corresponding to a weld line in the cavity, so as to implement any one of the methods for eliminating weld line bulges of an injection molded part, so that the weld line is eliminated from the injection molded part formed after injection molding.

[0048] The injection mold contains a cavity structure, and a glue-reducing layer is carefully set inside the cavity corresponding to the position of the weld line. This design is to be able to effectively implement a series of methods for eliminating weld line bulges of injection molded parts. Through the application of these methods, it can be ensured that after the injection molding process is completed, the obtained injection molded parts can completely eliminate the weld line, thereby improving the appearance quality and structural integrity of the product.

[0049] Obviously, the above embodiments are merely examples for clear description and are not limitations of the implementation methods.

[0050] For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived from this are still within the protection scope of the invention.

Claims

1. A method for eliminating bulging of weld lines of injection molded parts, characterized in that: include: A glue-reducing layer is provided in the cavity of the injection mold at the corresponding weld line of the injection molded part; The injection speed is reduced and the injection is performed to the reduced-glue layer, so that the thickness of the injection molded part formed after the injection mold is injected is reduced at the reduced-glue layer.

2. The method for eliminating bulging of weld lines of injection molded parts according to claim 1, characterized in that: The thickness of the reduced-glue layer is 0.3 mm to 1.2 mm.

3. The method for eliminating bulging of weld lines of injection molded parts according to claim 2, characterized in that: The distance between the edge of the reduced-glue layer and the weld line is 10 mm to 14 mm.

4. The method for eliminating bulging at the weld line of an injection molded part according to any one of claims 1 to 3, characterized in that: The rubber-reducing layer is iron added on the movable mold side of the mold.

5. The method for eliminating bulging at the weld line of an injection molded part according to any one of claims 1 to 3, characterized in that: The injection molding speed is 12 mm / s to 18 mm / s.

6. The method for eliminating bulging at the weld line of an injection molded part according to any one of claims 1 to 3, characterized in that: The injection molding time is 2 to 4 seconds.

7. The method for eliminating bulging at the weld line of an injection molded part according to any one of claims 1 to 3, characterized in that: The mold temperature during injection molding is 32°C to 38°C.

8. The method for eliminating bulging at the weld line of an injection molded part according to any one of claims 1 to 3, characterized in that: Also includes: Determine the glue reduction position of the weld line through mold flow analysis; The glue reduction layer is arranged at the glue reduction position.

9. An injection mold, characterized in that: The method comprises a mold cavity, wherein a glue reducing layer is provided at a position corresponding to a weld line in the mold cavity, so as to implement the method for eliminating weld line bulges of an injection molded part as claimed in any one of claims 1 to 8, so that the weld line is eliminated from the injection molded part formed after injection molding.

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