A plastic bottle preform with an annular groove in the middle
By setting an annular groove and guide ribs in the middle section of the plastic preform, the problems of stress concentration and uneven molding in traditional plastic preforms are solved, resulting in a longer service life and molding precision, and improved production stability and product quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN ZIJIANG ENTERPRISE CO LTD
- Filing Date
- 2025-09-19
- Publication Date
- 2026-07-31
AI Technical Summary
The traditional design of a smooth, stress-free central section of a plastic preform leads to stress concentration, making it prone to cracking during blow molding and use, and also results in insufficient molding precision.
An annular groove with a rounded transition is set in the middle section, and guide ribs are set on the inner wall. Combined with the smooth transition design of the hemispherical protrusion and the bottom of the groove, stress buffering and uniform raw material flow path are provided.
It significantly reduces the risk of mechanical weaknesses in the middle of plastic bottles, extends service life, improves molding accuracy, reduces cracking and wall thickness deviation, and enhances stacking stability and product qualification rate.
Smart Images
Figure CN224576992U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of plastic packaging molding technology, specifically a plastic bottle preform with an annular groove in the middle. Background Technology
[0002] Plastic preforms are particularly suitable for plastic bottle manufacturing scenarios in the packaging fields of food, beverages, and daily chemical products where structural strength and molding stability are required. As the core intermediate body for plastic bottles after injection molding and blow molding, the structural design of plastic preforms directly determines the mechanical properties, molding accuracy, and production efficiency of the final plastic bottle. Currently, most traditional plastic preforms widely used in the market adopt an integrated tubular structure, which is divided into the bottle mouth section, middle section, and bottom section from top to bottom. Among them, the middle section is the transition area connecting the bottle mouth and the bottom. In order to simplify the injection mold structure and reduce the molding difficulty, this middle section is usually designed as a straight tubular structure with a smooth surface. However, the aforementioned traditional smooth tubular central structure has significant defects in practical applications, affecting the performance and production adaptability of the preform. During blow molding, the preform needs to be heated and softened before being stretched and expanded by high-pressure gas to fit the mold cavity. The central section is the core stress area for radial and axial stretching of the bottle body. The smooth tubular structure lacks an effective stress dispersion design, resulting in stress concentration in a specific area of the central section. This area becomes the mechanical weak point of the blow-molded plastic bottle. During subsequent filling, transportation, or use, it is very easy to generate stress concentration during the blow molding stretching process when subjected to changes in internal and external pressure or external impact, leading to cracking and reducing the service life of the plastic bottle. In view of this, the present invention solves the above-mentioned technical problems by proposing a plastic bottle preform with an annular groove in the middle. Utility Model Content
[0003] To address the shortcomings of the aforementioned background technology, this utility model provides a technical solution for a plastic preform with an annular groove in the middle. By setting an annular groove with a rounded transition in the middle section, a reasonable stress buffer and dispersion path is provided for the blow molding stretching process, avoiding stress concentration problems and significantly reducing the risk of the middle of the plastic bottle becoming a weak point in mechanical strength. This reduces the likelihood of breakage caused by pressure changes or external impacts during subsequent use, extending the service life of the plastic bottle. At the same time, the guide ribs on the inner wall of the annular groove can guide the softened raw material to flow evenly along the axial direction. Combined with the smooth transition design between the hemispherical protrusion and the bottom of the groove, the flow of raw material is not obstructed. This solves the molding defects that are prone to occur in traditional preform blow molding, such as excessive wall thickness deviation and bottle body skewing, ensuring the molding accuracy of the final product.
[0004] The present invention provides the following technical solution: a plastic bottle preform with an annular groove in the middle, comprising a tubular bottle preform body, wherein the bottle preform body is integrally connected with a bottle mouth section, a middle section and a bottom section in sequence along the axial direction; A ring-shaped groove is provided on the outer circumference of the middle section. Multiple hemispherical protrusions are evenly provided on the bottom of the ring-shaped groove. Multiple guide ribs are provided on the inner wall of the ring-shaped groove along the axial direction of the preform body. The number of hemispherical protrusions is six, and the number of guide ribs is four. Both the hemispherical protrusions and the guide ribs are distributed in a ring array along the circumference of the annular groove.
[0005] As a preferred technical solution of this utility model, the annular groove and the preform body are integrally injection molded.
[0006] As a preferred embodiment of this utility model, the two ends of the guide rib extend to the top edge and bottom edge of the annular groove, respectively.
[0007] As a preferred embodiment of this utility model, the hemispherical protrusion and the bottom of the annular groove are smoothly transitioned by an arc surface, and the bottom of the annular groove and the groove wall are smoothly transitioned by an arc surface.
[0008] As a preferred embodiment of this utility model, the outer circumferential surface of the bottle mouth section is provided with a threaded structure for engaging with the bottle cap, and the end of the bottom section is a hemispherical structure.
[0009] In a preferred embodiment of this invention, the height of the guide rib is less than the depth of the annular groove.
[0010] Compared with the prior art, the present invention has the following beneficial effects: Compared to the shortcomings of traditional smooth tubular structures lacking stress dispersion design in the middle section, this utility model provides a reasonable stress buffer and dispersion path for the blow molding stretching process by setting an annular groove with a rounded transition in the middle section. This avoids stress concentration problems, significantly reduces the risk of the middle of the plastic bottle becoming a weak point in mechanical structure, reduces the possibility of breakage caused by pressure changes or external impacts during subsequent use, and extends the service life of the plastic bottle. At the same time, the guide ribs on the inner wall of the annular groove can guide the softened raw material to flow evenly along the axial direction. Combined with the smooth transition design between the hemispherical protrusion and the bottom of the groove, it avoids obstruction of raw material flow and solves the molding defects such as excessive wall thickness deviation and bottle body skewing that are prone to occur in traditional bottle preform blow molding, ensuring the molding accuracy of the final product.
[0011] To address the issues of nesting and deformation caused by the smooth, unsupported center of traditional preforms during stacking, this invention features an annular groove that provides basic positioning for stacking. The hemispherical protrusion at the bottom of the groove acts as a physical barrier, effectively preventing nesting between adjacent preforms due to their smooth surfaces. Furthermore, the guide ribs extending axially along the groove form a support structure that disperses the longitudinal pressure generated during stacking and the impact of transport vibrations, preventing permanent deformation of the central section due to concentrated stress. This structural design, combined with the fitting shape of the bottle mouth and bottom, improves the axial positioning stability during stacking, reduces blow molding failures caused by preform deformation, thereby increasing product qualification rate and reducing production costs. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is the front view of the present invention; Figure 3 This is a schematic diagram of the guide rib structure of this utility model; Figure 4 This is a partially enlarged view of the present invention.
[0013] In the figure: 1. Preform body; 101. Bottle mouth section; 102. Middle section; 103. Bottom section; 2. Annular groove; 201. Hemispherical protrusion; 202. Guide rib. Detailed Implementation
[0014] 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.
[0015] Please see Figure 1-4 As shown, a plastic preform with an annular groove in the middle includes a tubular preform body 1, and the preform body 1 is integrally connected with a bottle mouth section 101, a middle section 102 and a bottom section 103 in sequence along the axial direction. A ring groove 2 is provided on the outer circumference of the middle section 102. Multiple hemispherical protrusions 201 are evenly provided on the bottom of the ring groove. Multiple guide ribs 202 are provided on the inner wall of the ring groove 2 along the axial direction of the preform body 1. There are six hemispherical protrusions 201 and four guide ribs 202. Both the hemispherical protrusions 201 and the guide ribs 202 are arranged in a ring array along the circumference of the annular groove 2.
[0016] The annular groove 2 and the preform body 1 are integrally injection molded structures.
[0017] The two ends of the guide rib 202 extend to the top edge and bottom edge of the annular groove 2, respectively.
[0018] The hemispherical protrusion 201 and the bottom of the annular groove 2 are smoothly transitioned by an arc surface, and the bottom of the annular groove 2 and the groove wall are smoothly transitioned by an arc surface.
[0019] The outer circumferential surface of the bottle mouth section 101 is provided with a threaded structure for engaging with the bottle cap, and the end of the bottom section 103 is hemispherical.
[0020] The height of the guide rib 202 is less than the depth of the annular groove 2.
[0021] During the injection molding process, the preform body 1 is injection molded in one step through a mold. The annular groove 2 and the preform body 1 adopt an integrated injection molding structure, which can avoid structural splicing defects caused by subsequent processing, and at the same time ensure the connection strength between the annular groove 2 and the middle section 102. During the mold design, the arc transition between the hemispherical protrusion 201 and the bottom of the annular groove 2, and the arc transition between the bottom of the annular groove 2 and the groove wall are precisely processed. During injection filling, the raw material can flow evenly along the smooth transition surface, reducing molding defects such as air bubbles and material shortages, and ensuring the structural integrity of the hemispherical protrusion 201 and the guide rib 202. In addition, the thread structure on the outer periphery of the bottle mouth section 101 is injection molded simultaneously to reserve a matching structure for the subsequent bottle cap assembly. The hemispherical end of the bottom section 103 is also formed in one step to provide a basic shape for bottom stretching during blow molding. After injection molding, the preforms enter the stacking and storage stage. The annular groove 2 on the outer circumference of the middle section 102 provides basic positioning for stacking. The hemispherical protrusions 201 at the bottom of the annular groove 2 are distributed along the annular array, which can form a physical barrier when adjacent preforms are stacked, preventing nesting of the middle section of the preforms due to the smooth surface. At the same time, the guide ribs 202 on the inner wall of the annular groove 2 extend to the top and bottom edges of the groove, and the height of the guide ribs 202 is less than the depth of the annular groove 2. This ensures that the guide ribs do not exceed the groove and affect the stacking tightness, and can form axial support when the stack is under pressure, dispersing the pressure on the middle section 102 and preventing it from undergoing permanent deformation due to compression. The threaded structure of the bottle mouth section 101 and the hemispherical end of the bottom section 103 cooperate to make the axial positioning of the preforms more stable during stacking, further reducing the risk of deformation. During blow molding, the preform body 1 is heated and softened before being fed into the blow molding mold. High-pressure gas pushes the preform wall to stretch and expand. The annular groove 2 in the middle section 102 effectively disperses stress during stretching through the arc transition structure between the groove bottom and the groove wall, preventing the middle section from becoming a high-risk area for cracking. The guide ribs 202 on the inner wall of the annular groove 2 extend axially, guiding the softened raw material to flow evenly along the preform axis, reducing wall thickness deviation. At the same time, the smooth transition design between the hemispherical protrusion 201 and the groove bottom does not obstruct the flow of raw material, ensuring that the overall wall thickness of the bottle is consistent after blow molding. The threaded structure of the bottle mouth section 101 maintains its shape stability during blow molding, while the hemispherical end of the bottom section 103 forms the arc structure of the bottle bottom as the raw material is stretched, adapting to the final use requirements of the plastic bottle.
[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, in the accompanying drawings of this utility model, the fill patterns are merely for distinguishing layers and do not constitute any other limitation.
[0023] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A plastic bottle preform having an annular groove disposed in the middle portion, comprising: The preform body (1) is tubular and is integrally connected in sequence along the axial direction with a bottle mouth section (101), a middle section (102) and a bottom section (103). The feature is that: a ring groove (2) is provided on the outer circumferential surface of the middle section (102), and a plurality of hemispherical protrusions (201) are uniformly provided at the bottom of the ring groove, and a plurality of guide ribs (202) are provided on the inner wall of the ring groove (2) along the axial direction of the preform body (1). The number of hemispherical protrusions (201) is six, and the number of guide ribs (202) is four. Both the hemispherical protrusions (201) and the guide ribs (202) are arranged in a ring array along the circumference of the annular groove (2).
2. A plastic bottle preform having an annular groove formed in the middle portion thereof as set forth in claim 1, wherein: The annular groove (2) and the preform body (1) are integrally injection molded structures.
3. A plastic bottle preform with an annular groove in the middle as described in claim 1, characterized in that: The two ends of the guide rib (202) extend to the top edge and bottom edge of the annular groove (2), respectively.
4. A plastic bottle preform with an annular groove in the middle as described in claim 1, characterized in that: The hemispherical protrusion (201) and the bottom of the annular groove (2) are smoothly transitioned by a circular arc surface, and the bottom of the annular groove (2) and the groove wall are smoothly transitioned by a circular arc surface.
5. A plastic bottle preform with an annular groove in the middle as described in claim 1, characterized in that: The outer circumferential surface of the bottle mouth section (101) is provided with a threaded structure for cooperating with the bottle cap, and the end of the bottom section (103) is a hemispherical structure.
6. A plastic bottle preform with an annular groove in the middle according to claim 1, characterized in that: The height of the guide rib (202) is less than the depth of the annular groove (2).