Hot-fill bottle type capacity adjustment and negative pressure rapid venting design structure

Abstract

This utility model discloses a hot-fill bottle type capacity adjustment and negative pressure rapid venting design structure, relating to the field of blow molding technology. The structure includes a mold cavity with a groove on its inner wall; a negative pressure block is detachably installed within the groove; a gap for rapid venting is formed between the outer periphery of the negative pressure block and the side wall of the groove; and a replaceable capacity adjustment shim is provided between the bottom of the groove and the negative pressure block. During blow molding, air between the preform and the mold can be quickly expelled through the venting gap, ensuring the bottle material completely adheres to the mold, achieving uniform crystallization and improving the product's heat resistance. Simultaneously, by replacing capacity adjustment shims of different thicknesses, the axial position of the negative pressure block can be conveniently and precisely adjusted, thereby fine-tuning the final bottle capacity.

Description

Technical Field

[0001] This utility model relates to the field of blow molding technology, and more specifically, to a hot-fill bottle type capacity adjustment and negative pressure rapid exhaust design structure. Background Technology

[0002] In the production of plastic bottles, especially PET bottles that require hot filling, blow molding is a key process that determines the final performance of the product. In order for the bottle to withstand the subsequent filling of high-temperature liquids without shrinkage or deformation, the bottle material must form a uniform and fully crystalline structure during the blow molding process to obtain good heat resistance.

[0003] In traditional blow molding, a long-standing technical challenge is venting efficiency. When the preform expands rapidly under high-pressure gas, the air between it and the mold cavity wall must be quickly expelled. If venting is inadequate, residual air will form an air cushion, hindering complete adhesion between the preform and the mold surface. This not only leads to appearance defects such as incomplete blowing, surface pitting, and poor transparency, but also causes uneven material stretching and incomplete crystallization, severely damaging the bottle's heat resistance and mechanical strength, resulting in a high product scrap rate.

[0004] Furthermore, in commercial production, it is often necessary to make minor adjustments to the standard capacity of bottles to accommodate different market regulations or specific customer needs. The traditional solution usually involves remanufacturing the entire mold cavity or core components, which is not only extremely costly but also has a long production cycle, severely impacting production flexibility and responsiveness to market changes.

[0005] Therefore, there is an urgent need in this field for a new type of blow molding die structure that can fundamentally solve the problem of rapid venting to ensure high-quality molding, and also provide a low-cost, high-efficiency, and easy-to-operate solution for adjusting bottle capacity. Utility Model Content

[0006] The present invention provides a hot-fill bottle type capacity adjustment and negative pressure rapid exhaust design structure, which can alleviate the above-mentioned problems.

[0007] To alleviate the above problems, the technical solution adopted by this utility model is as follows:

[0008] A hot-fill bottle type capacity adjustment and negative pressure rapid venting design structure includes a mold cavity, the inner wall of which is provided with a groove; a negative pressure block is detachably installed in the groove; an venting gap is formed between the outer peripheral surface of the negative pressure block and the side wall of the groove; a capacity adjustment shim is provided between the bottom of the groove and the pressure-bearing surface of the negative pressure block for adjusting the axial installation position of the negative pressure block in the groove, thereby changing the final molding capacity of the bottle.

[0009] Compared with the prior art, the beneficial effects of this utility model are:

[0010] (1) By creating a groove in the inner wall of the mold cavity, a continuous, annular venting gap is precisely formed between the groove and the negative pressure block installed therein. This gap constitutes a large-area, low-resistance venting channel. During the bottle blowing process, the gas between the preform and the mold can be quickly discharged along this channel, completely eliminating the air cushion effect. This ensures that the preform material can completely and tightly adhere to the mold surface (including the surface of the negative pressure block), thereby achieving uniform stretching and high crystallization. The resulting bottle has excellent heat resistance, uniform wall thickness, and perfect surface quality, fully meeting the requirements of high-end hot filling. At the same time, the groove structure also provides a stable radial positioning for the negative pressure block, ensuring the uniformity and consistency of the venting gap.

[0011] (2) The capacity is finely adjusted by using a capacity adjustment shim set between the bottom of the groove and the negative pressure block. When the bottle capacity needs to be changed, the operator only needs to open the mold, take out the negative pressure block, and replace it with a shim of different thickness. The whole process does not require any machining or replacement of the expensive mold body. The operation is simple and time-saving. This "shim-type" adjustment method shortens the mold modification cycle of several days or even weeks to a few minutes, greatly reducing the cost of production adjustment and giving the production line unprecedented flexibility.

[0012] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, embodiments of this utility model are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a first cross-sectional structural schematic diagram of the present invention, in which some grooves are not fitted with negative pressure blocks, and some grooves are fitted with negative pressure blocks;

[0015] Figure 2 This is a second cross-sectional view of the present invention, in which negative pressure blocks are installed in all the grooves;

[0016] Figure 3 This is a schematic diagram of the structure of the negative pressure block and capacity adjustment pad described in this utility model;

[0017] In the diagram: 10-mold cavity, 11-groove, 20-negative pressure block, 30-capacity adjustment shim, 40-mold venting gap. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0019] See attached document Figure 1 , Figure 2 and Figure 3 This embodiment provides a hot-fill bottle type capacity adjustment and negative pressure rapid venting design structure, mainly applied in hot-fill bottle blow molding dies made of materials such as PET. The structure includes:

[0020] Mold cavity 10: This is the main part of the blow molding process, and the shape of its inner surface determines most of the bottle's shape.

[0021] Groove 11: One of the key features of this invention. One or more grooves 11 are machined into the inner wall of the mold cavity 10, typically corresponding to areas where specific reinforcing ribs or flat panels need to be formed on the bottle body. These grooves 11 have precise dimensions for accommodating and positioning the negative pressure block 20.

[0022] Negative pressure block 20: also known as mold insert or vacuum block. It is a separate component whose shape matches the groove 11 and is detachably installed within the groove 11. The side surface of the negative pressure block 20 facing the center of the mold forms part of the final shape of the bottle. The negative pressure block 20 is fixed to the mold cavity 10 by fasteners such as bolts (not shown) to ensure stable positioning during mold closing and blow molding.

[0023] Capacity Adjustment Shim 30: This is a sheet or ring-shaped precision shim placed between the bottom of the groove 11 (i.e., the end furthest from the mold center) and the pressure-bearing surface of the negative pressure block 20. The shim 30 is made of a pressure-resistant and heat-resistant metal material, such as copper or stainless steel. Its core function is to serve as a thickness reference to raise or lower the negative pressure block 20. A series of shims 30 with different thicknesses (e.g., thicknesses increasing in increments of 0.1 mm or 0.05 mm) can be pre-manufactured for use.

[0024] Mold venting gap 40: This is the core structure for achieving rapid venting in this invention. It is not a separate component, but rather constitutes the tiny space between the outer peripheral wall of the negative pressure block 20 and the inner wall of the groove 11. This gap 40 is continuously distributed along the circumference of the negative pressure block 20, forming an annular venting channel with a cross-sectional area much larger than that of a conventional venting hole. The width of this gap 40 is precisely designed, preferably between 0.2 mm and 0.8 mm, with 0.5 mm in a typical embodiment. This size ensures that air flows out quickly and without obstruction, while effectively preventing molten plastic material from overflowing under this high pressure and forming burrs (i.e., flash).

[0025] Working principle and operation procedure:

[0026] At the start of the blow molding cycle, a preform heated to a specific stretching temperature is placed within a closed mold cavity 10. High-pressure gas is then injected into the preform, causing it to expand rapidly. As the expanding preform material contacts the inner wall of the mold, particularly the surface of the negative pressure block 20, residual air between the preform and the mold is compressed. Thanks to the presence of the venting gap 40, this compressed air can be immediately and rapidly expelled from the mold through this low-resistance annular channel around the negative pressure block 20. This "penetrating" venting method is highly efficient, preventing the formation of air cushions on the bottle wall due to poor venting, thus ensuring 100% tight contact between the preform material and all surfaces of the mold (including the negative pressure block). As a result, the bottle material is fully and uniformly stretched and oriented, resulting in more perfect crystallization and significantly improved heat resistance, compressive strength, and surface finish of the final product.

[0027] When the production line requires a minor adjustment to the bottle capacity (e.g., from 500ml to 495ml), operators do not need to replace the entire expensive mold. The operation process is as follows:

[0028] First, open the mold and loosen the fasteners used to secure the negative pressure block 20.

[0029] Next, remove the negative pressure block 20 and the capacity adjustment pad 30 below it from the groove 11.

[0030] Then, select a new gasket 30 with a different thickness according to the required adjustment of capacity. For example, if you want to reduce the bottle capacity, choose a gasket that is thicker than the original one; if you want to increase the capacity, choose a gasket that is thinner.

[0031] Place the new gasket 30 at the bottom of the groove 11, then put the negative pressure block 20 back on the gasket and tighten it again.

[0032] Due to the change in the thickness of the gasket 30, the axial position of the negative pressure block 20 within the mold cavity 10 is also precisely altered. A thicker gasket will cause the negative pressure block 20 to move towards the center of the mold, thereby reducing the final internal volume of the bottle. Conversely, a thinner gasket will also reduce the internal volume. This process is simple and quick, and can be completed within minutes, greatly improving production flexibility and responsiveness to market demands.

[0033] In summary, this invention cleverly combines a negative pressure block, a replaceable gasket, and a circumferential venting gap into a groove structure, providing an integrated and low-cost solution that simultaneously solves two major technical challenges in hot-fill bottle production, thus possessing extremely high industrial application value.

[0034] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A hot-fill bottle type capacity adjustment and negative pressure rapid venting design structure, comprising a mold cavity (10), characterized in that, The inner wall of the mold cavity (10) is provided with a groove (11); a negative pressure block (20) is detachably installed in the groove (11); an exhaust gap (40) is formed between the outer peripheral surface of the negative pressure block (20) and the side wall of the groove (11); a capacity adjustment shim (30) is provided between the bottom of the groove (11) and the pressure bearing surface of the negative pressure block (20) for adjusting the axial installation position of the negative pressure block (20) in the groove (11), thereby changing the final molding capacity of the bottle.

2. The structure according to claim 1, characterized in that, The exhaust gap (40) is continuously arranged along the circumference of the negative pressure block (20) to form an annular exhaust channel.

3. The structure according to claim 1, characterized in that, The capacity adjustment pad (30) is made of copper, stainless steel or hard alloy material.

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