Method and apparatus for the manufacture of plastic containers

Abstract

A method for manufacturing a container, comprising the steps of: molding a substantially cylindrical preform having a mouth and a preform body having a sidewall and a bottom using a mold having a female part and a male part; and blow molding the preform to provide a container, wherein the male part has at least one corrugation designed to provide an inner surface of the preform body located close to the mouth, the corrugation designed to provide a first inner surface of the preform body equal to at least 30% of the surface of the sidewall of the preform body, the first inner surface having an Rmc [%] comprised between 1% and 12%, and the blow molding process is adapted to provide a container having respective interior regions provided starting from the first inner surface of the preform body having an Rmc [%] comprised between 3% and 30%.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for the manufacture of plastic containers. [Background technology]

[0002] A fairly common problem in equipment for the production and storage of plastic containers, typically shaped like vases or cups, relates to the difficulty of properly stacking and / or removing the containers due to friction between the respective portions of the inner surface of the container placed below and the outer surface of the container that is fed from above for stacking and lifted for removal. Summary of the Invention [Problem to be solved by the invention]

[0003] To try to eliminate this drawback, attempts have been made to increase the accuracy of the release of the containers and to generally reduce the friction between the inner and outer surfaces of the stacked containers.

[0004] It is an object of the present invention to provide a method and apparatus for the production of plastic containers that can improve upon the background art in one or more of the above aspects.

[0005] Within this goal, it is an object of the present invention to provide a method and apparatus for the production of plastic containers which significantly reduces the risk of jamming during stacking and / or removal of the manufactured containers.

[0006] A further object of the present invention is to devise a method and an apparatus for the production of plastic containers that makes it possible to increase the productivity of the apparatus. [Means for solving the problem]

[0007] In particular, it is an object of the present invention to provide a method and apparatus for manufacturing plastic containers that is reliable, relatively easy to provide, and at a competitive cost.

[0008] This object, as well as these and other objects that will become more apparent hereinafter, are achieved by a method and apparatus for the production of plastic containers according to claim 1, optionally comprising one or more of the features of the dependent claims.

[0009] Further features and advantages of the present invention will become more apparent from the description of some preferred, but not exclusive, embodiments of the method and apparatus for the production of plastic containers according to the invention, which are shown by way of non-limiting examples in the accompanying drawings, in which: [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view of a preform obtained by the molding step of the method according to the invention; [Figure 2] FIG. 1 is a side view of a container obtained by a preform blow molding process. [Figure 3] FIG. 1 is a side view of containers stacked on top of each other. DETAILED DESCRIPTION OF THE INVENTION

[0011] Referring to the cited figures, the present invention relates to a method for manufacturing a container 20, particularly a plastic container.

[0012] Advantageously, the containers 20 have a cup-like or tumbler-like shape so that they can be stacked on top of one another (as shown in FIG. 3).

[0013] The method according to the present invention comprises the steps of forming a substantially cylindrical preform 10 having a mouth 11 and a preform body 12 .

[0014] The preform body 12 includes a sidewall and a bottom. Molding processes include, for example, molding by injection or compression, or by compression injection.

[0015] The molding process is carried out by a mold having a female part and a male part. After the molding step, the method provides for blow molding the preform 10 to provide a container 20 .

[0016] According to the invention, the male part has at least one corrugated portion designed to provide an inner surface 12 a of the preform body 12 located adjacent the mouth 11 .

[0017] The corrugations are particularly designed to provide a first inner surface 12 a of the preform body 12 that is equal to at least 30% of the surface of the sidewall of said preform body 12 .

[0018] The preform 12 defines at least one second inner surface 12b extending from the opposite side of the mouth 11 from the first inner surface 12a.

[0019] Advantageously, the preform 12 also defines a third inner surface 12c extending from an opposite side of the second inner surface 12b relative to the first inner surface 12a.

[0020] In practice, as shown in FIG. 1, the first inner surface 12a extends close to the mouth 11 of the preform 10, the third inner surface 12c extends close to the bottom of the preform 10, and the second inner surface 12b extends to an intermediate position between the first inner surface 12a and the third inner surface 12c.

[0021] The first inner surface 12a has an Rmc [%] comprised between 1% and 12%. Next, the blow molding process is adapted to provide a container 20 having respective first interior regions 20a provided starting from the first inner surface 12a of the preform body 12 having an Rmc [%] comprised between 3% and 30%.

[0022] Rmc [%] is understood to refer to the percentage of the load-bearing surface. Its definition and calculation method are set out in the ISO 21920-2:2021 standard, which effectively replaces what was previously referred to as Rmr in the previous, now withdrawn, UNI EN ISO 4287:2002 standard.

[0023] The parameter Rmc can also be defined as the length of the stationary contact surface expressed as a percentage of the evaluation length at a depth "c" below the highest peak.

[0024] It is also possible to derive Rmc as the length of the stationary contact surface expressed as a percentage of the evaluation length at a height "c" above the mid-plane.

[0025] Advantageously, the first inner surface 12a has an Rmc [%] (measured at a distance "c" above the mid-plane) comprised between 1% and 10%, more preferably comprised between 3% and 7%.

[0026] In the latter case, the blow molding process is adapted to provide a container 20 having respective interior regions 20a provided starting from a first inner surface 12a of the preform body 12 having an Rmc [%] comprised between 4% and 28%.

[0027] Advantageously, the corrugations are designed to provide a first inner surface 12 a of the preform body 12 that is equal to at least 50% of the sidewall surface of the preform body 12 .

[0028] The corrugations are obtained by sandblasting the male part. Of course, nothing prevents obtaining the corrugations of the male part by other abrasion techniques, even of the chemical type.

[0029] The method according to the invention provides for stacking the containers 20 inside one another after the blow-molding step, with their respective mouths 11 oriented upwards.

[0030] According to a further aspect, the present invention relates to an apparatus for manufacturing a container 20, comprising a mold for molding a substantially cylindrical preform 10 having a mouth 11 and a preform body 12 with a side wall and a bottom.

[0031] The mold includes a female part and a male part. The apparatus further comprises a device for blow-molding the preform 10 to provide the container 20 .

[0032] In particular, the male part has at least one corrugated portion designed to provide an inner surface 12 a of the preform body 12 located adjacent the mouth 11 .

[0033] The corrugations are designed to provide a first inner surface 12 a of the preform body 12 that is equal to at least 30% of the surface of the sidewall of the preform body 12 .

[0034] The first inner surface 12a has an Rmc [%] comprised between 1% and 12%. The blow molding process is also adapted to provide a container 20 having respective interior regions 20a provided starting from the first inner surface 12a of the preform body 12 having an Rmc [%] comprised between 3% and 30%.

[0035] Advantageously, the corrugations are designed to provide a first inner surface 12 a of the preform body 12 that is equal to at least 50% of the surface of the sidewall of the preform body 12 .

[0036] The corrugations are obtained by sandblasting the male part. According to a further aspect, the invention relates to a container 20, characterized in that it can be obtained by the method according to the above description.

[0037] To complete the data provided herein, data regarding the corrugations of the preform 12 and container 20 in various regions of two different samples is provided below.

[0038] [Table 1]

[0039] In fact, the present invention has been found to achieve its intended aims and objectives and to provide a method and apparatus for producing containers with greatly reduced risk of incorrect stacking and / or removal without any appreciable increase in equipment cost or reduction in production rate.

[0040] The invention thus conceived is susceptible to numerous modifications and variations, all of which fall within the scope of the appended claims. All details may further be replaced by other technically equivalent elements.

[0041] In practice, the materials used can be any, depending on the requirements and the state of the art, as long as they fit the specific application, as well as the conditional shapes and dimensions.

[0042] The disclosure of Italian Patent Application No. 102022000026220, from which this application claims priority, is incorporated herein by reference.

[0043] Where technical features described in any claim are followed by reference signs, those reference signs are included solely for the purpose of enhancing the comprehension of the claim, and therefore such reference signs do not have any limiting effect on the interpretation of the respective elements identified by such reference signs as examples.

Claims

1. A method for the manufacture of a container (20), comprising the steps of: molding a substantially cylindrical preform (10) with a mouth (11) and a preform body (12) with a sidewall and a bottom by means of a mold comprising a female part and a male part; and blow-molding the preform (10) to provide a container (20), the male part comprising at least one corrugation designed to provide an inner surface (12a) of the preform body (12) located adjacent to the mouth (11), the corrugation wherein the blow molding step is designed to provide a first inner surface (12a) of the preform body (12) equal to at least 30% of the surface of the side wall of the preform body (12), the first inner surface (12a) having an Rmc [%] comprised between 1% and 12%, and the blow molding step is adapted to provide a container (20) having respective interior regions (20a) provided starting from the first inner surface (12a) of the preform body (12) having an Rmc [%] comprised between 3% and 30%.

2. 2. The method according to claim 1, wherein the first inner surface (12 a) has an Rmc [%] comprised between 1% and 10%, and the blow molding process is adapted to provide a container (20) having the respective interior regions (20 a) provided starting from the first inner surface (12 a) of the preform body (12) having an Rmc [%] comprised between 4% and 28%.

3. 10. The method according to claim 1, wherein the Rmc [%] is calculated as defined in the ISO 21920-2:2021 standard.

4. 10. The method according to claim 9, wherein the corrugations are designed to provide a first inner surface (12a) of the preform body (12) that is equal to at least 50% of the surface of the side wall of the preform body (12).

5. 10. A method according to any one of the preceding claims, characterized in that the corrugations are obtained by sandblasting the male part.

6. 10. A method according to any one of the preceding claims, characterized in that it comprises the step of stacking the containers (20) inside one another, with their respective mouths (11) oriented upwards.

7. An apparatus for manufacturing a container (20), said apparatus comprising a mold with a female part and a male part for molding a substantially cylindrical preform (10) having a mouth (11) and a preform body (12) with a sidewall and a bottom, and a device for blow molding said preform (10) to provide said container (20), said male part comprising at least one corrugated portion designed to provide an inner surface (12a) of said preform body (12) located adjacent to said mouth (11), said corrugated portion comprising 1. An apparatus for manufacturing a container (20), characterized in that the apparatus is designed to provide a first inner surface (12a) of the preform body (12) equal to at least 30% of the surface of the side wall of the preform body (12), the first inner surface (12a) having an Rmc [%] comprised between 1% and 12%, and the blow molding process is adapted to provide a container (20) having respective interior regions (20a) provided starting from the first inner surface (12a) of the preform body (12) having an Rmc [%] comprised between 3% and 30%.

8. 8. An apparatus for manufacturing a container (20) according to claim 7, characterized in that the corrugated portion is designed to provide a first inner surface (12a) of the preform body (12) equal to at least 50% of the surface of the side wall of the preform body (12).

9. 9. An apparatus for manufacturing containers (20) according to claim 7 or 8, characterized in that said corrugations are obtained by sandblasting said male part.

10. A container (20) made by the method according to any one of claims 1 to 6.

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