Bottom shape structure of a thin-walled plastic container

Abstract

The present invention provides a bottom shape structure for a thin-walled and thin-walled multi-layer co-injected plastic container, which includes a bottom center concave region, a bottom surface transition bottom corner position, and a bottom foot. The bottom center concave region is connected to the bottom foot through the bottom surface transition bottom corner position. The bottom center concave region has a bottom center gate, and the bottom center gate bulges towards the opening direction of the container to form a bulge, forming a bottom center gate concave arc position. The bottom of the bulge is transitioned with the bottom center concave region through an arc. This bottom shape structure effectively improves the flow length ratio, making the product easy to mold and full, and the material distribution is uniform.

Description

Technical Field

[0001] The present invention relates to thin-walled and thin-walled multi-layer co-injected plastic containers, and particularly to the bottom shape structure of thin-walled and thin-walled multi-layer co-injected plastic containers. Background Art

[0002] With the rapid development of the plastic industry and the continuous improvement of plastic properties, plastic products have been widely used. Most plastic products are injection molded. For the injection molding process, the flow length ratio of plastics is very important, which directly affects the wall thickness and quality of plastic products.

[0003] The flow length ratio of plastics refers to the ratio of the length of plastic melt flow to the wall thickness. The smaller the flow length ratio, the poorer the fluidity of the plastic melt. Different plastics have different flow length ratios. For example, the flow length ratio of LDPE is 270, that of HDPE is 230, that of PP is 250, that of PS is 210, and that of ABS is 190.

[0004] However, under the existing injection molding equipment conditions and injection molding process conditions, it is very difficult for the flow length ratio of plastic products to reach the optimal flow length ratio value. For example, the flow length ratio of single-layer and multi-layer plastic products injection molded with PP plastic can only reach about 180. The reason is found that for plastic products on the market currently, the connection between adjacent two structures at the bottom is a corner, that is, connected through a corner. Such a connection has a rather abrupt flow turning angle, which not only affects the pressure loss and flow rate, but also increases the shear stress inside the plastic product and increases energy consumption; and poor fluidity also leads to incomplete injection at the front end of single-layer products, material accumulation and uneven thickness at the bottom of the middle layer of multi-layer products, it is not easy for the middle layer to flow and extend towards the front end of the container, and the flow front edge is uneven with a large height difference and uneven wall thickness. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention aims to propose a bottom shape structure of a thin-walled and thin-walled multi-layer co-injected plastic container, optimize and improve the bottom shape and structure of the existing plastic container, so as to accelerate the flow rate of the plastic melt and increase the flow length ratio.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A bottom shape structure of a thin-walled and thin-walled multi-layer co-injected plastic container includes a bottom center concave region, a bottom surface transition bottom corner position, and a bottom foot. The bottom center concave region is connected to the bottom foot through the bottom surface transition bottom corner position. The bottom center concave region has a bottom center gate. The bottom center gate bulges towards the opening direction of the container to form a bulge, forming a bottom center gate concave arc position. The bottom of the bulge is transitioned with the bottom center concave region through an arc.

[0008] Further, the bottom center concave region includes a center concave surface, a center region transition position, and a center side wall. The center concave surface is a flat surface or an arc surface, the center side wall is an inclined wall, the center region transition position is an arc, and the center concave surface is smoothly connected to the center side wall through the center region transition position.

[0009] Further, the center concave surface is an arc surface that extends from the center of the container bottom towards the container side wall and gradually decreases in the radial direction.

[0010] Further, the radian of the center region transition position is R5 - R10.

[0011] Further, the bottom surface transition foot position includes an arc segment, a straight segment, and a bottom side surface transition arc position. One end of the arc segment is smoothly connected to the center side wall, the other end of the arc segment is connected to the straight segment, the straight segment is connected between the arc segment and the bottom side surface transition arc position, and the bottom side surface transition arc position is smoothly connected to the inner surface of the container side wall.

[0012] Further, the radian of the arc segment and the bottom side surface transition arc position is R3 - R8.

[0013] Further, the width W1 of the straight segment is 0.6 mm - 1.5 mm, and its height H3 from the bottom surface of the foot is 0.5 mm - 1.5 mm.

[0014] Further, the foot includes a bottom angle grounding surface, a foot inner side surface, and a foot guiding arc. One end of the foot guiding arc is smoothly connected to the bottom side surface transition arc position, the other end of the foot guiding arc is connected to the foot inner side surface, and the foot inner side surface is connected between the foot guiding arc and the bottom angle grounding surface.

[0015] Further, the foot inner side surface is an inclined surface, and the angle A2 between it and the outer surface of the container side wall is 6° - 10°.

[0016] Further, the diameter D of the bottom center gate concave arc position is ∅5 - 10 mm, and the depth H1 is 0.3 - 0.5 mm.

[0017] The present invention optimizes the design of the shape and structure of the bottom of the existing plastic container. Specifically, the bottom center gate is improved, and the design of the bottom center gate concave arc position is adopted to solve a series of adverse effects brought by the convex gate in the prior art; in addition, the corner connection between each part of the bottom is improved, and the arc is used for smooth connection to reduce problems such as large flow resistance, slow flow rate, difficult molding, and incomplete injection at the front end caused by the sharp corner transition in the prior art. Based on such an optimized design, the flow length ratio of the thin-walled and thin-walled multi-layer co-injection plastic container of the present invention can reach more than 200, breaking through the bottleneck that the flow length ratio in the prior art can only reach 180.

[0018] The present invention also has the following beneficial effects:

[0019] 1. Significantly reduce the protrusion of the product gate;

[0020] 2. Increase the flow length ratio of the injection-molded product, making it easier to mold and fill single-layer and multi-layer thin-walled products;

[0021] 3. The middle layer materials of multiple layers are evenly distributed, without material accumulation, splashing flow, or mixing sequence;

[0022] 4. Reduce molding conditions such as injection pressure and temperature, shorten the molding cycle, and save energy and reduce consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described and elaborated below with reference to the accompanying drawings.

[0024] Figure 1 It is a schematic diagram of a thin-walled and thin-walled multi-layer co-injection plastic container according to the present invention.

[0025] Figure 2 is Figure 1 A cross-sectional view of the bottom shape structure of the plastic container in

[0026] Figure 3 is also Figure 1 A cross-sectional view of the bottom shape structure of the plastic container in

[0027] Figure 4 is also Figure 1 A cross-sectional view of the bottom shape structure of the plastic container in, which shows the dimension markings.

[0028] Figure 5 It is a cross-sectional view of another embodiment of the bottom shape structure of the plastic container of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solution of the present invention will be more clearly and completely elaborated below by describing the preferred embodiments of the present invention with reference to the accompanying drawings.

[0030] As Figure 1 shown, the thin-walled and thin-walled multi-layer co-injection plastic container 100 according to the present invention includes a container side wall 10 and a container bottom 20.

[0031] The shape structure of the container bottom 20 includes a bottom center concave region 2, a bottom surface transition bottom corner position 3, and a bottom foot 4. The bottom foot 4 contacts the tabletop or other support to support the plastic container 100 on the support. The bottom center concave region 2 is located within the circular region surrounded by the bottom feet 4 and is concave in the opening direction of the plastic container 100. The bottom center concave region 2 is connected to the bottom feet 4 through the bottom surface transition bottom corner position 3.

[0032] As Figure 2 andFigure 4 As shown, at the center of the bottom center recessed area 2, there is a bottom center gate 1, and the plastic melt enters the mold cavity from this bottom center gate 1. The bottom center gate 1 bulges into a bulge 11 in the opening direction of the plastic container 100, forming a concave arc position at the bottom center gate. The bulge 11 at this concave arc position increases the wall thickness at the bottom center gate 1 accordingly. Therefore, the cooling rate of the material is slower than that of the surrounding area. The material at the bottom center gate 1 is elastic and has space. Then, when the valve pin is closed, the remaining material in the valve pin channel is pushed by the valve pin and incorporated into the concave arc position of the bottom center gate, reducing the volume and height of the sprue protruding outward. Thus, it avoids the situation that the valve pin cannot be closed in place due to the too fast cooling rate of the gate position, as well as the too long residue of the sprue and the impact on the solidified sprue position when the valve pin is closed. From Figure 2 As can be seen, the lower surface of the bottom center gate 1 and the lower surface of the bottom center recessed area 2 are almost on the same plane, without obvious outward convexity, changing the phenomenon of the sprue protruding outward in the prior art. Thus, it also solves the adverse effects brought by the sprue protruding outward.

[0033] Preferably, the diameter D of the concave arc of the bottom center gate 1 is ∅5 - 10 mm, and the depth H1 is 0.3 - 0.5 mm.

[0034] As Figure 2 and Figure 4 shown, the bottom center recessed area 2 includes a center recessed surface 21, a center area transition position 22, and a center side wall 23. The center recessed surface 21 is a plane or an arc surface. In the Figures 1 to 4 scheme shown, the center recessed surface 21 is a plane, and the vertical height H2 between the center recessed surface 21 and the bottom transition foot position 3 of the bottom surface is 1.8 mm - 3 mm. The center area transition position 22 is an arc, the center side wall 23 is an inclined wall, and the center recessed surface 21 is smoothly connected to the center side wall 23 through the center area transition position 22. The smooth connection of the arc reduces the flow resistance of the plastic melt, enabling the plastic melt to flow effectively and quickly.

[0035] Preferably, the radian of the center area transition position 22 is R5 - R10, and the center side wall 23 forms an angle A1 with the horizontal plane, and this A1 angle is 40 ± 10°.

[0036] One end of the center side wall 23 is connected to the center area transition position 22, and the other end is connected to the bottom transition bottom corner position 3.

[0037] As Figure 3 and Figure 4As shown, the bottom surface transition foot position 3 includes an arc segment 31, a straight segment 32, and a bottom side surface transition arc position 33. One end of the arc segment 31 is smoothly connected to the central side wall 23, and the other end is connected to the straight segment 32. The straight segment 32 is connected between the arc segment 31 and the bottom side surface transition arc position 33. The bottom side surface transition arc position 33 is smoothly connected to the inner surface of the container side wall 10. Here, the bottom center concave region 2 is smoothly connected to the bottom surface transition foot position 3 by the arc segment 31, reducing the resistance of the plastic melt flow and increasing the melt fluidity; the bottom surface transition foot position 3 is smoothly connected to the container side wall 10 by the bottom side surface transition arc position 33, avoiding the formation of nodes with nearly right angles at the transition position in the prior art and the resulting large flow resistance and scattered flow guidance, which cause splashing flow and disordered flow.

[0038] Preferably, the radian of the arc segment 31 and the bottom side surface transition arc position 33 is R3 - R8.

[0039] The straight segment 32 is substantially in the horizontal direction. Preferably, its width W1 is 0.6 mm - 1.5 mm, and the height H3 from the lower surface of the foot 4 is 0.5 mm - 1.5 mm.

[0040] The foot 4 includes a bottom angle grounding surface 41, a foot inner side surface 42, and a foot guiding arc 43. One end of the foot guiding arc 43 is smoothly connected to the bottom side surface transition arc position 33, and the other end is connected to the foot inner side surface 42. The foot inner side surface 42 is connected between the foot guiding arc 43 and the bottom angle grounding surface 41.

[0041] The foot inner side surface 42 is an inclined surface, which is inclined inward at an angle A2 with the outer surface of the container side wall 10. Preferably, the angle A2 is 6° - 10°.

[0042] Preferably, the height H4 of the foot 4 is 2 mm - 4 mm, and the width W2 of the bottom angle grounding surface 41 is 0.3 mm - 0.5 mm.

[0043] Here, through the slope design of the foot inner side surface 42 and the arc design of the foot guiding arc 43, it is beneficial for demolding, guiding the melt to flow towards the opening end of the container, and at the same time avoiding splashing flow and disordered flow at the foot corner.

[0044] Furthermore, the upper and lower surfaces of the bottom surface transition foot position 3 are respectively smoothly connected to the container side wall 10 and the foot 4 in the form of an arc, which improves the melt fluidity as a whole, increases the flow length ratio, and improves the problems of splashing flow and disordered flow at the corner in the prior art.

[0045] Such as Figure 5As shown, this is another embodiment of the present invention. In this embodiment, the central concave surface 21' of the central concave area 2' at the bottom is an arc surface 210', and this arc surface 210' gradually decreases from the center of the central concave area 2' at the bottom and along the radial direction. Through this large-arc surface 210', it is smoothly connected to the transition position of the central area in a gradient manner, which is beneficial to guiding the molten material to pass through orderly when manufacturing thin-walled parts, avoiding disordered flow, reducing fluid resistance and accelerating the flow rate at the same time, making it easier to form thin-walled products and making the front-end injection more full.

[0046] Based on the design of the bottom shape structure of the above container, taking a 15-gram coffee cup as the test object, the inner and outer layers and the middle layer were tested multiple times using injection station A and injection station B respectively. The test results show that the flow length ratio of the plastic melt using the bottom shape structure of the present invention exceeds 200, and it is easy to form single-layer and multi-layer structures. The flow distribution in the middle layer is uniform, the main body thickness is uniform and controllable, and there is no phenomenon that the middle layer extends to the bottom skirt corner. The test data are shown in Table 1 below:

[0047] Table 1:

[0048]

[0049] The above specific embodiments only describe the preferred embodiments of the present invention, rather than limiting the protection scope of the present invention. Without departing from the design concept and spirit scope of the present invention, various deformations, substitutions and improvements made by those of ordinary skill in the art to the technical solutions of the present invention based on the written description and drawings provided by the present invention shall all fall within the protection scope of the present invention. The protection scope of the present invention is determined by the claims.

Claims

1. The bottom shape structure of a thin-walled plastic container, comprising a bottom center concave region, a bottom surface transition bottom corner position, and a bottom foot. The bottom center concave region is connected to the bottom foot through the bottom surface transition bottom corner position. A bottom center gate is provided at the center of the bottom center concave region. Characterized in that, The bottom center gate bulges towards the opening direction of the container to form a bulge, thereby forming a bottom center gate concave arc position. The bulge increases the wall thickness at the bottom center gate accordingly. The lower surface of the bottom center gate and the lower surface of the bottom center concave region are on the same plane. The bottom of the bulge and the bottom center concave region are transitioned by an arc; the bottom center concave region includes a center concave surface, a center region transition position, and a center side wall. The center concave surface is a plane or an arc surface. The center side wall is an inclined wall. The center region transition position is an arc. The center concave surface is smoothly connected to the center side wall through the center region transition position; the bottom surface transition bottom corner position includes an arc segment, a straight segment, and a bottom side surface transition arc position. One end of the arc segment is smoothly connected to the center side wall. The other end of the arc segment is connected to the straight segment. The straight segment is connected between the arc segment and the bottom side surface transition arc position. The bottom side surface transition arc position is smoothly connected to the inner surface of the container side wall.

2. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The center concave surface is an arc surface, which extends from the center of the container bottom towards the container side wall and gradually decreases in the radial direction.

3. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The radian of the center region transition position is R5 - R10.

4. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The radian of the arc segment and the bottom side surface transition arc position is R3 - R8.

5. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The width W1 of the straight segment is 0.6 mm - 1.5 mm, and its height H3 from the lower surface of the bottom foot is 0.5 mm - 1.5 mm.

6. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The bottom foot includes a bottom corner grounding surface, a bottom foot inner side surface, and a bottom foot guiding arc. One end of the bottom foot guiding arc is smoothly connected to the bottom side surface transition arc position. The other end of the bottom foot guiding arc is connected to the bottom foot inner side surface. The bottom foot inner side surface is connected between the bottom foot guiding arc and the bottom corner grounding surface.

7. The bottom shape structure of the thin-walled plastic container according to claim 6, Characterized in that, The bottom foot inner side surface is an inclined surface, and the included angle A2 between it and the outer surface of the container side wall is 6° - 10°.

8. The bottom shape structure of the thin-walled plastic container according to claim 1, Characterized in that, The diameter D of the bottom center gate concave arc position is ∅5 - 10 mm, and the depth H1 is 0.3 - 0.5 mm.

9. A thin-walled plastic container, comprising a container side wall and a container bottom, Characterized in that, The shape structure of the bottom of the container is the bottom shape structure described in any one of claims 1-8.

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