MXPA06007232A - Method of swage-forming of container or preform internal threads and container and preform having such internal threads - Google Patents

Abstract

A method of making a plasticcontainer having an internally threaded finish. The container is made from a preform (10) having a body (12) and an integral neck (14), and the body of the preform is expanded within a mold cavity to form the body of the container. Either prior to or subsequent to blow molding the preform body, at least one internal thread (20) is formed in the neck by engaging an inner surface of the neck with a first tool (22) having a peripheral channel (28), engaging an outer surface of the neck with a second tool (24) having a peripheral bead (32), and causing relative rotation of the neck and tools to swage at least one internal thread in the neck. Such a preform and such a container are also disclosed.

Description

METHOD OF TRAINING FOR BENDING OF INTERNAL THREADS OF CONTAINER OR PREFORM AND RECIPIENT OR PREFORM THAT HAS THE INTERNAL THREADS FIELD OF THE INVENTION The present application is directed to plastic containers and preforms for blow molded plastic containers, as well as an information method of internal threads on the container or preform.

BACKGROUND OF THE INVENTION In the manufacture of plastic containers, such as containers made of monolayers or multilayers of polyethylene tereptalate (PET), it is conventional to mold a container preform having a body and a finish with one or more external threads. The overall finish is molded to its final geometry in the preform, where the body of the preform is subsequently blow molded to the desired geometry of the container body. However, this manufacturing technique is not suitable for the manufacture of shapes or containers having internal threads due, among other reasons, although it is difficult to disassemble a preform having internal threads from which the container is formed. It is therefore desirable to provide a method of forming internal threads upon completion of a preform of Ref .: 173826 plastic containers and provide a preform or finished container with internal threads.

BRIEF DESCRIPTION OF THE. INVENTION In accordance with one embodiment of the invention, there is provided a method for forming at least one internal thread in the neck of a preform or plastic container. The method includes the steps of: a) adjusting the internal surface of the neck with a first tool having a peripheral channel; b) adjusting the external surface of the neck with a second tool having a peripheral edge; c) generate a relative rotation between the neck and the tools to grind an internal thread in the neck between the channel and edge. In various alternative implementations of the method, the step of generating relative rotation includes: - rotating both tools; - rotating the preform; - rotating the preform and turning one of the first and second tools and - rotating both tools and the preform. The method can be carried out between a preform and a body of the preform can subsequently be blow molded to form a container. Alternatively, the method can be carried out on the leather of a container, such as a container formed by blowing from the preform. The preform can be formed by injection molding or compression molding. The preform can be molded with an internal thread on the neck. This provides for the production of the neck of a preform or container having both a molded external thread and a cored internal thread. The internal thread can be formed either with or without a change in step. The thread may simply be a groove, such as a continuous groove around the neck. In accordance with one embodiment of the method, the method can further include the step of smoothing an upper surface of the neck while forming the internal thread. The smoothing step can be accompanied by the application of heat and pressure to an upper surface of the neck. In other embodiments, a separate end ring is provided which is assembled to the neck such that the ring is received on an outer surface of the neck.

This final ring can have an internal thread and can itself be an article molded in plastic. In various modalities of the method, one or more tools may be hot. Thus, the neck of the preform or container is heated to facilitate the formation of the internal threading. According to another embodiment, an article comprising a preform or plastic container is provided. The article has a cylindrical neck with a substantially uniform wall thickness and at least one internal cored thread in the neck. The article may further comprise a final ring that is secured on the neck and has at least one external thread. Again, the external thread can be formed by injection molding or compression molding. The container can be a blow-molded plastic container that is formed from the preform. The following description and accompanying figures that are incorporated and that constitute a part of this specification, illustrate various embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a perspective view of a molded preform without thread in accordance with an aspect of the present invention; Figure 2 is a schematic diagram illustrating the gripping of an internal thread in the preform of Figure 1; Figure 3 is a schematic diagram illustrating the gripping of an internal thread in a molded container of the preform of Figure 1; Figure 4 is a sectional view of the section of Figure 3 within the area 4; Figure 5 is a perspective view of a preform and the junction of a terminal ring having both internal and external thread in accordance with another embodiment of the invention; Fig. 6 is a schematic diagram illustrating grouting in an internal thread in a preform having a molded internal thread; Fig. 7 is a sectional view of a preform having a molded external thread and an internal, cored thread; Fig. 8 is a sectional view of a preform with a horizontal groove formed internally (as the internal threading) in accordance with another embodiment; Figure 9 is a schematic diagram illustrating various alternative relative movements of the preform of the first and second tool, in accordance with various embodiments of the invention; and Figure 10 is a schematic diagram illustrating both the combined pitch of the internal thread in a container and the smoothing of the neck surface of the container.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 illustrates the preform of an exemplified container 10 having a body 12 and an integral neck 14. The neck 14 preferably has a round outline and in this embodiment, when being molded it has no internal or external threads. The specific preform 10 illustrated in FIG. 1 is molded with an external retaining edge to cooperate with the cap indicated in structure in a secure closure for final container and a support flange 18 that facilitates the handling of the preform and the recipient. The edge 16 and the flange 18 are optional. The cylindrical neck 14 is generally of a uniform radial wall thickness. The preform 10 can be molded from a plastic monolayer construction by injection or by molding its compression such as from pET, or from a multilayer plastic construction having a matrix of structural layers of TET, for example, and a or more intermediate layers of barrier material such as ethylene vinyl alcohol (EVOH) or nylon the barrier layers may or may not extend within the neck of the preform 14. In accordance with one aspect of the present invention, the internal threads are formed by tipping in the neck 14 either before or after blow molding the body of the preform 12. As illustrated in Figure 2, one or more internal threads 20 are embocked with the neck preform 14 before blow-molding the neck shape 12. These threads 20 are cored within the neck of the preform by means of a first rotary tool 22 that adjusts the inner surface of the neck 14 and a second tool 24 which adjusts the external surface of the neck 14. The internal tool 22 includes a disc 26 with a peripheral channel 28. The internal tool 24 includes a disc 30 having a peripheral flange or flange 32. With the tool 22 in the adjustment with the inner surface of the neck 14 and the tool 24 fitted with the external surface of the neck 14, the tools (and preform) are rotated until this flange 32 deforms or pinches the plastic material of the neck 14 into the channel 28 on the tool 22. This deformation can be assisted and promoted if desired, by heating 1 or more fabrics 22, 24; alternatively, the grouting can be a cold forming operation. After the internal threads 20 are formed in the neck 14, the preform 10 is placed in a suitable blow molding by the hot body of the preform 12 which is blow molded to form the body 12a (Figure 3) of a container. Figure 3 illustrates an alternative technique for grinding internal threads 20 in the neck preform 14 after blow molding the body of a container 12a. The reference numerals in Figure 3 which are identical to those in Figures 1-2 indicate identical parts. Since the internal threads are embossed in the neck preform before and subsequently to the blow molding in the body preform, the neck 14 remains in substantially uniform radial thickness as illustrated in Figure 4. Figure 5 illustrates a training method of a preform or container having both internal and external threads in the preform of the final container. After the spit, one. or more internal threads 20 within the neck 14 of the preform or container (Figure 2 or Figure 3), have a separate terminal ring 34 that is secured on the outer surface of neck 1. The end ring 34 has one or more external threads 36 preformed here. As a modification to FIG. 5, the retaining bounce 16 and / or flange or support 18 may be formed in the ring 34 before the preform. Thus, the final container according to the embodiment of Figure 5 includes both internal and external threads, with the internal threads being cored within the neck of the container and the external threads being formed on a separate terminal ring. Figures 6 and 7 illustrate another method of marking a preform that has both internal and external threads. In this preform 40, the preform is molded with internal threads 42 on the neck of the preform 44. After molding and before subsequent to blow molding the body of the preform, the tipping tools 22, 24 are used to form the preforms. internal threads 46 on the neck 44. It is desirable to heat the neck 14 before or during the thread forming operation. "This heating can be carried out by driving the tools 22, 24. The neck is preferably heated to a higher level at room temperature, such as within the range of 50 ° to 100 ° to finish the PET The temperature to finish the neck preferably should not have the glass transition temperature Tg after the neck material by more than about 40 ° to 50 ° For example, heating to finish the neck at a level of 120 ° or more can cause distortion and deformation of the neck.A contact time of 5 seconds can e is sufficient for the formation of the threads when the neck 14 has a thickness of 0.5 to 1 millimeters (0.019 to 0.039"). a shorter contact time, such as in the order of one second, is not suitable unless the finished neck is very thin; this is not desirable in the embodiments of Figs. 1-4, but it can be accommodated for the variety of Fig. 5. Thus, one or more internal ones are embocked and formed on the wall E of the preform and the neck of the container 1. All or a portion of the preform or neck of the container may be crystallized before or after the formation of the internal threads 20 to prevent shrinkage or distortion. This is particularly desirable in hot fill applications, where the temperature of the material placed in the container on the other hand can cause shrinkage or distortion of the final container. The crystallization of the final container can be extended to the radial thickness and axial length of the neck, including the retaining flange and / or support flange 18 provided, if desired. In another alternative embodiment, Figure 8 shows a cross section of the preform 50 having a body 52 and a neck 54. An internal thread in the form of a continuous horizontal groove 56 is formed around the neck circumference on the neck. Figure 9 is similar to Figure 2 when illustrating the gripping operation. However, Figure 9 shows several directions of movement of the first tool 22 (arrows 22a, 22b), second tool 24 (arrows 24a, 24b) and the neck of the preform 14 (arrow 14a). The preform as illustrated has a body 12 and a neck 14 with a mouthpiece forming the internal thread. The preform has a longitudinal axis CL. The first tool 22 can be rotated approximately on an axis substantially parallel to the longitudinal axis of the preform (arrow 22a) and the first tool can move axially along the longitudinal axis of the preform (arrow 22b). The second tool 24 has similar directions of movement as the first tool (arrows 24a and 24b), but it is understood that the second tool may be turned in the opposite direction to the first tool in any given operation. Overlapping, the second tool moves in an elongated arc around the neck of the preform (arrow 31) when the internal thread is formed. The preform itself can rotate around its longitudinal axis between (arrow 14a), with one or both of the tools. As a result of this relative direction of movement, it is possible to form a thread having either a horizontal thread or groove alignment, or a thread or groove that is positioned with respect to the longitudinal axis of the preform. Fig. 10 shows another alternative embodiment wherein an external thread gripping 62 is formed in the neck of a container 60. When the first internal thread is formed, the first tool 80 also softens the upper surface 64 of the neck 66 of the container by means of of a smoothing tool 82 possessed adjacent to the upper surface 64 of the neck. The smoothing plate 82 is held in position against the upper surface of the neck by a forced compression 84 and the smoothing plate can be hot so as to soften the upper surface and facilitate the smoothing. The first and second tool 80, 90 are shown rotating around eg is parallel, in opposite directions. The internal donut can be used to join a method of finishing a lid to seal the container, or a piece of equipment such as an outlet duct. The preforms may be of any suitable plastic construction, such as in PET single-layer multilayer construction in PET layers alternating with resin barrier layers such as ethylene vinyl alcohol (EVOH) or nylon. The preforms can be injection molded or compression molded. In the same way, the rings can be plastic constructions molded by injection or compression. By providing terminal rings separated from the preforms, the end rings can be of any desired construction material, either the same or more preferably different from the construction material of the preform. For example, the terminal ring can be of TETT construction, post-consumer resin (PCR), process trowel (REG), polypropylene (PP), polyethylene (PE) or polyethylene naphthalate (PEN). When the terminal ring is of polyester construction (eg, PET, PEN or process trailer), the end ring may be fully or partially crystallized when molded. This may be accompanied by using rapid crystallization materials or suitable process conditions for the manufacture of the finished ring, such as high temperature molding, slow cooling molding, hot areas in the mold cavity. The terminal ring may alternatively be fully or partially crystallized in a post-molding operation. In other words, the material and manufacturing conditions of the end ring can be selected separately from the material and manufacturing conditions of the preform to achieve desired operating characteristics in the determined area of the preform and finished end container. In addition, the preform can be molded with thin-walled sections without having to order the flow of material in a final layer area, which reduces the material cost and time of the molding cycle. The end ring is secured to the neck of the preform by means of interference equipment (pressure equipment or shrinking equipment) adhesive or desoldering. In the end ring and / or the neck of the preform may be provided with suitable means to prevent the ring from rotating on the neck. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention described herein. It is intended that the specification and examples be considered as exemplary, with a true scope of the invention as indicated by the following claims. It is noted that, with regard to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (24)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A method for forming at least one internal thread in a plastic neck of a preform or container characterized in that it comprises the steps of providing a preform molded having a body and a neck and before or subsequent to blow molding the body of the preform to form a container: (a) adjusting the lower surface of the neck with a first tool having a peripheral channel; (b) adjusting an outer surface of the neck with a second tool having a peripheral flange and (c) generating a relative rotation between the neck and the tool to grind at least one internal thread in the neck between the channel and flange. The method according to claim 1 characterized in that the step of generating the relative rotation comprises one of: (a) rotating both tools, - (b) rotating the preform or container; (c) rotating the preform of the container and rotating one of the first and second tool; (d) turn both tools and the preform or container. 3. The method according to claim 1, characterized in that the method is carried out on the neck of a preform. 4. The method according to claim 1 characterized by a further comprising the step of crystallizing all or a part of the neck of the preform or container or the formation of the internal thread. 5. The method according to claim 1, characterized in that the method is carried out on the neck of a container. 6. The method according to claim 1, characterized in that the preform is formed by injection molding or compression molding. The method according to claim 1 characterized in that it further comprises the step of smoothing an upper surface of the neck while the internal thread is formed. 8. The method according to claim 1 characterized by the thread is formed with or without a change in its placement. 9. The method according to claim 1 characterized by the thread is a groove. 10. The method according to claim 1 characterized in that the groove is a continuous groove around the neck. A method for forming at least one internal thread in a plastic neck of a preform or container characterized in that it comprises: (a) adjusting the internal surface of the neck with a first tool having a peripheral channel; (b) fitting an outer surface of the neck with a second tool having a peripheral flange, - (c) generating a relative rotation between the neck and the tool to grind at least one internal thread in the neck between the channel and flange; (d) providing a terminal ring and (e) placing the end ring on the neck such that the ring is received on an outer surface of the neck. 12. The method according to claim 11, characterized in that the terminal ring has an external thread. The method according to claim 11 characterized in that the terminal ring is a plastic molded end ring having an external thread. The method according to claim 1 characterized in that the neck is a molded neck having an external thread. 15. The method according to claim 14, characterized in that the external thread is molded and the internal thread is offset axially. 16. The method according to claim 1 characterized in that it includes the heating of one or both tools. 17. The method according to claim 1, characterized in that it includes the heating of one or more of the neck, the first tool and the second tool. 18. The method according to claim 1, characterized in that the internal thread is useful for joining a seal or equipment. 19. A plastic preform or container made according to the method according to claim 1 characterized in that it has at least one internal thread emboquillada in the neck, alone or in combination with an external thread molded with the neck. 20. An article comprising an injection molded or compression molded plastic preform characterized by having a body and a neck, or a container made from the preform by blow molding the body of the preform, the preform or neck of the container: a) is a cylindrical neck of a substantially uniform wall thickness and (b) has at least one internal thread emboquillada in the neck. 21. An article characterized in that it comprises a plastic preform or container having: (a) a cylindrical neck with substantially uniform wall thickness and (b) at least one internal thread emboquillada in the neck, and also comprises a terminal ring secured on the neck and has at least one internal thread. 22. An article according to claim 20, characterized in that the article is a preform. 23. An article according to claim 20, characterized in that the neck has an external thread molded integrally. 24. An article according to claim 20, characterized in that the article is a blow molded container.