MXPA97006034A - Method and apparatus for producing a tubular container with cie media - Google Patents

Abstract

The present invention relates to a method for producing an essentially tubular container body of plastic material which is open at one end and has an opposite end, a drain mouth with closing means thereon in the same, the The container body has a substantially cylindrical wall between said ends thereof, the closing means being integrated with said opposite end of the container body said method comprises: introducing the molten plastic material into an injection mold to form there a section comprising a body having a tubular part which is open at one end and has a mouth at its opposite end and a closing means formed integrally with said body and providing a hinged closure member for said mouth, subjecting the tubular portion of said section to a pulling operation in which a wall of said tubular part passes through a gap for h The wall undergoes a reduction in thickness while being lengthened in length to form the tubular container body whose one end which is open and whose opposite end is formed by said mouth with said closing means formed integrally there, the reduction of said wall thickness being between 2.5 and 5 times to cut the tubular article at said open end to prepare said open end for closing to form a container after the tubular article is filled with its contents, and wherein the removal of the section of the injection mold, a mechanical device moves the closing means to a position in which all parts of the closing means are located at a distance from a geometric center axis of the section at most giving a distance between the geometric central axis and a surface of the separation located closer to said center axis

Description

METHOD AND APPARATUS FOR PRODUCING A TUBULAR CONTAINER WITH CLOSURE MEDIA The present invention relates to a method and an apparatus for producing a tubular container according to the preambles of the respective independent clauses. By tubular container is meant a container with continuous walls which has a cross section taken through the wall of the container being substantially arbitrary eg circular, elliptical, polygonal, having at least one corner, a flat surface, a curved surface inwards, etcetera. A round, oval, or multi-sided vessel forms the modalities of the invented container.

In the injection molding of the tubular plastic containers, the maximum length which can be obtained from the tubular part of the container is determined by the selected material and the wall thickness of the tubular part. In addition, the wall thickness may not be less than approximately between 0.5 millimeters regardless of the plastic material used in the injection molding. This relationship is further clarified later in the body of this description.

In the injection molding of containers, the flow length of the melted plastic material supplied and, therefore, the unit formed in the injection molding process is maximized by the thickness of the material. In purely practical terms, it has been proven that injection molded products having a wall thickness of less than 0.5 millimeters can not be produced in mass production lines. Cf., for example, the book by Menges / Mohren, "How to Make Injection Molds", 1986, by Hanser Publishers (ISBN 0-19-520744-0 Oxford University Press), page 66.

Plastic tubular containers have recently been adapted for use as tubes, for example, for toothpaste, for hand creams, et cetera. However, for the reasons indicated above it has been necessary to select a thickness of material for the tubular part to be unnecessarily large or, otherwise, it has been necessary to restrict the length of the tubular part.

The present invention relates to a technique by which, compared to the prior art techniques, the length of the tubular part of the container extends at least about 4 times, at the same time as the thickness of the material in the part tubular is reduced by approximately 4 times. Simultaneously, the material properties of the tubular part are improved, in particular the mechanical material properties. The material properties of the tubular part of the container will be modified, involving, among other things, that the material in the walls of the tubular part will be softened and molded more easily than in the prior art containers. Therefore the emptying of the contents of such containers will be facilitated.

This object is achieved through techniques as described in the characterizing clauses of the independent clauses and annexes.

The present invention makes considerable material savings with the result that the costs involved in the production of such containers are drastically reduced compared to those that are applied to the tubular containers produced according to the prior art technique. The cost savings of the order of the magnitude of 40% have been achieved.

Other embodiments of the present invention are defined below in the appended subclauses.

The present invention will now be described in greater detail here below with particular reference to a number of drawing figures in which: Figure 1 shows a section obtained by injection molding; Figure 2 shows a container formed by extension of the section; Figures 3-6 are cross sections through an apparatus, the apparatus being illustrated in mutually subsequent production phases of the section; Figures 6-9 show an apparatus for forming the section by extending the tubular part of the section in different phases of the formation process; Y Figures 8a, b show parts of the apparatus of Figures 7-9 to extend the tubular portion of the section.

Figure 1 shows an axial cross section through an injection molding section 1, comprising a tubular part 13 and an adjacent part 19 including a drain opening or mouth 12. As a rule, the associated part tapers towards the mouth 12. The tubular part and, therefore, the section is open at that end 10 which is opposite the opening or drain mouth 12. At its other end 11, for example, at that end that spans the mouth, the tubular part 13 it is connected to the tapered part 19. Closing means 14 included in the section are shown as being placed in a position where, as a rule, they abut against the material parts of the opening or drain mouth sealingly. 12. The closing means 14 constitute an integrated part of the section and is connected through a hinge-type pivot 18 with the rest of the section.

Figure 2 shows an axial cross section through that container 2 which is obtained once the section illustrated in figure 1 has been extended, in which the thickness of the material of the tubular part of the section has been reduced over the extension or prolongation of the tubular part. The tubular part of the container, formed by the tubular part 13 of the section, has been given the reference number 23. The tapered part 19 of the section, together with the closing means 14 integrally pivoted with the tapered part is not influenced by the training process. The end 20 which is opposite the emptying opening or mouth 12 is still open, while the other end 21 of the tubular part integrally connects with the tapered part 19. All the parts which are included in the container 2 constitute a unit in which the parts merge into each other without any seams or mechanical joints. In other words, the material in the container forms a single piece of material (an integral unit).

Figures 3-6 show a section through an injection mold 3 for forming a plastic material in the section 1. The injection mold 3 comprises a front part 30, an intermediate part 31 and a rear part 32. The parts of the Injection mold boards comprise a forming cavity 34. The figures show the injection mold once the plastic material has been supplied inside the forming cavity 34.

Figures 7-8 schematically illustrate the sections through the parts of an apparatus for extending the section 1 formed in the injection mold 3.

Figure 7 shows that part of the apparatus where the tubular part 13 of the section 1 is surrounded by the heating means 50 which are butted against the outer surface of the tubular part. A mandrel 51 is generally inserted within the section as to stabilize the section during the heating process. In certain embodiments, the mandrel 51 is also provided with the means for temperature conditioning of the section.

Figure 8 shows the section once the material in its tubular part 13 has passed through a gap 4 (see Fig. 8a) for reducing the thickness of the material under the simultaneous extension of the section.

Figures 8a and 8b show in detail parts of the pull ring 40 and a pull ring mandrel 61 cooperating with the pull ring when both of these devices are moved by the driving means (not shown in the figures) to positions in which separation 4 is formed between the pull ring and the pull ring mandrel. Figure 8a shows the gap 4 without any plastic material being located there, and Figure 8b shows the wall of the section 1 in the passage through the gap 4 formed by the pull ring 40 and the pull ring mandrel 61.

In Figures 8a, b the pull ring 40 is shown in a mode in which it is composed of two ring parts 42 and 43. Each pull ring is provided with a channel 44, 45 for carrying the thermal medium. The pull ring has a guide surface 46 facing the pull ring mandrel 61, against whose surface the material in the section is pressed as it passes through the gap 4. The guide surface makes an angle with the surface 60 of the pull ring mandrel and fuses on the pull ring surface 41 located essentially parallel with the surface of the pull ring mandrel.

The surface 41 constitutes the junction definition of the separation in which the region of the separation where it becomes narrowest. The pull ring mandrel is generally provided with channels 63 for the thermal medium.

Figure 9 shows the container 2 formed of the section once the trimming device 52 has cut the superfluous material at the open end 10 of the extended section 1 (the future filling opening).

In figure 3, the three parts 30, 31 and 32 of which the injection mold 3 is constructed are joined and form the internal cavity 34 of the injection mold with a shape corresponding to the contemplated shape or contour of the section. A channel 33 runs through the front end 30, and is discharged into the internal cavity 34 in the region thereof where the emptying mouth 12 of the contemplated container is formed. The internal forming cavity 34 comprises two cavities of mutually interconnected parts, the one 34a for forming the section body and the other 34b for forming the closure means 14 of the section. An injection mold nozzle 35 is shown in connection with the channel 33. An arm 36 is movable by means (not shown) to and from the starting position illustrated in Figure 3.

In Figure 4, the injection mold is shown with the front part 30 separated from the intermediate part 31 interconnected with the rear part 32. In this position the mold is open and the parts of the section 1 are exposed.

Figure 5 shows the arm 36 displaced to a position in which the arm presses the closing means 14 against the mouth or emptying opening 12 of the section. During the displacement of the position which is shown in figures 3 and 4 the arm moves to a position which causes the arm, when moving from said position to the position of figure 5, to move the closing means 14 into a pivotal movement from the position assumed by the closing means in Figure 4 of the position assumed by the closing means in Figure 5.

In figure 6, the intermediate part 31 of the injection mold has been displaced from a position in which the intermediate part is abutting against the rear part 32. The section 1 has been removed from the male part 37 which is located inside the stretch on the injection molding of raismo. Arm 36 moves back to its starting position.

Figure 7 shows the section 1 placed between one or more heating means 50. In certain practical applications, in particular in a large material thickness of the tubular part 13 of the section, a mandrel 51 is also inserted within the section as a rule to constitute a complementary source of heat for the material during the heating cycle. The mandrel is generally provided with heat conditioning means, for example channels for a thermal medium.

Figure 8 shows the section once a pull ring 40 has passed through the tubular part of the section in the axial direction thereof and during the reduction of the thickness of the material of the tubular part. The pull ring is positioned to maintain a surface temperature on its surface 41, 46 facing the plastic material which is adjustable to a level within the range of about 50 and 70 ° C.

The mandrel (pull ring mandrel) 61 is positioned to be at least partially located within the section 1. The pull ring mandrel forms a gap 4 together with the pull ring 40. The mandrel is positioned to maintain the surface , facing the pull ring 40 to form the gap 4, at a temperature which is adjustable to a level within the range of about 50 and 100 ° C.

The separation 4 has a minimum separation width which is less than the thickness of the material of the injection molded section. The separation width is within the order of magnitude between 0.1 and 0.9 millimeters, preferably between 0.13 and 0.55 millimeters, and in special cases between 0.13 and 0.45 millimeters. After the passage of the separation, the thickness of the material of the tubular part of the section corresponds essentially to the separation width of the separation used in the reduction of the thickness of the material in the tubular part of the section.

The size of the extension of the tubular part and the size of the reduction are adapted to suit the desired properties in the finished container. The size of the reduction is selected to lie within the range of 2.5 and 5.0 times, preferably within a range of 3.5 to 3.5 times.

Figure 9 shows the finished container (see Figure 2) at positions in the end station once the trimming of the end region of the axially extended tubular part of the section la has taken place. As a result of this trimming operation, an essentially uniform defining edge will be achieved with respect to the opening in the end region 20 opposite the discharge opening or mouth 12.

The container 2 illustrated in Figures 2 and 9 has a thin-walled tubular part 23 which, at its end 20, has an opening whose size (cross-section) corresponds to the internal cross section of the tubular part. This facilitates the supply of the contents inside the container. The closure of the filling container after filling is effected simply by means of a welding process, for example heat punches which heat the material to the melting temperature. The thin-walled material quickly assumes the shape or contour that is determined by the shape of the matrices, as a rule a straight shape, and quickly arrives at the temperature which is necessary for the material to melt together and form a tight seal . At its other end 21, the container is of a construction form that completely corresponds to those that are obtained as a section in relation to the injection molding. The thin wall of the tubular part of the container implies that the material is deformable relatively easily and that the emptying of the container will therefore be facilitated.

Preferred thermoplastic materials in the practical application of the technology described above are polypropylene (PP), polyethylene terephthalate (PET), polyolefins (PE), and certain thermoplastic elastomers, for example styrene elastomers (SEBS). It will be obvious to a person skilled in the art that the technique as described in the foregoing is generally applicable to all plastic materials which have similar reforming properties, for example materials possessing properties corresponding to those required to be formed the container in the application of the technology described above.

It has been surprisingly proven that, for certain given materials, for example, polypropylene (PP), polyethylene terephthalate (PET), and PE polyolefins), it is possible to produce containers whose tubular part has been called "fold" properties. dead. " To achieve such properties, a material thickness is selected for the tubular part of the container within the range of 0.1 to 0.15 millimeters. The term "dead bending properties" is taken to mean those properties which are known from aluminum tubes, for example that the tube can retain its shape after compression. The elastic return action known from the above tubes of the plastic material will therefore be avoided.

The "dead bending" properties are completely unique properties of thin-walled plastic tubes. This ensures an almost complete emptying of the tube in use, which prevents the oxygen / air from being pulled back into the tube in relation to its emptying.

The above detailed description has been carried out with respect to a limited number of embodiments of the present invention, but a person with ordinary skill in the art will readily perceive that the present invention encompasses a large number of modalities without departing from the spirit and scope of the invention. The claims.

Claims (12)

R E I V I N D I C A C I O N S

1. A method for producing an essentially tubular container of a plastic material, in which the container is open at one end, and at its other end, is provided with a pour opening or mouth, in which the container forms an essentially cylindrical wall between its open end and its other end, in which the closing means constitute an integral part with the other end, and in which in the production of the container, a section is injected into an injection mold, characterized in that the material of plastic is supplied in the melted state to the injection mold and forms therein a section comprising a section body with a tubular part open at one end and provided at the other end with an opening constituting the mouth or opening for emptying the future container; that, as on the supply of the plastic material to the injection mold, integral closure means are formed with the other end of the section body and project from the other end of the section body, said closure means constitute the device of closure of the future recipient; that, after the formation of the section, the tubular part of the section body moves through an annular gap under the reduction of the thickness of the material of the tubular part; that the size of said reduction is located within the range of between 2.5 and 5.0 times, preferably within the range of between 3.5 and 4.5 times, that, with the step of separation, a body of extended length is formed; and that the extended section body is cut at its end opposite the opening or pouring mouth, for the formation of an essentially uniform edge whereby the body of the container is completed.

2. The method, as claimed in clause 1, characterized in that, with the removal of the injection mold section, a mechanical device moves the closing means to a position in which all the parts of the closing means are located at a distance from the geometric central axis of the section at most forming the distance between the geometric central axis of the separation and the surface of the separation located closer to the central axis.

3. The method, as claimed in clause 1, characterized in that, with the removal of the injection mold section, a mechanical device moves the closing means to a position in which all the parts of the closing means are located at a distance from the geometric central axis of the section at most being equivalent to the distance between the geometric central axis of the separation and the surface of the localized separation furthest from the central axis.

4. The method, as claimed in any of clauses 1-3, characterized in that at least a part of the material in the tubular part of the section is, by abutting against a hot mechanical surface, adjusted to a elevated temperature before the tubular part of the body of the section moves through the separation.

5. The method, as claimed in any of clauses 1-3, characterized in that the width of the separation of the separation is selected such that, after the passage of the separation, the thickness of the material in the tubular part of the section is located in the range of between 0.1 and 0.9 millimeters, preferably between 0.13 and 0.55 and, in special cases, in the range of between 0.13 and 0.45 millimeters.

6. The method, as claimed in any of the preceding clauses, characterized in that with the formation of the container, the material in the tubular part of the section is given a reduced thickness adapted to the material in question and involves the material obtaining properties of "dead bending".

7. The method, as claimed in any of the preceding clauses, characterized in that with the formation of the container, the thickness of the material in the tubular part of the section is reduced to a value within the range of between 0.1 and 0.15 millimeters.

8. The method, as claimed in any of the preceding clauses, wherein the tubular part is essentially circular in shape.

9. An apparatus for carrying out the method according to any of the preceding clauses, characterized in that the apparatus comprises an injection mold with an injection nozzle, a mold comprising two part cavities, a pull ring surrounding a mandrel and forming a separation between itself and the mandrel, and drive means for relative displacement of the pull ring and the mandrel in the longitudinal direction of the mandrel while maintaining the dimensions of the gap between the pull ring and the mandrel.

10. The apparatus, as claimed in clause 9, characterized in that the parts included in the apparatus form a composite unit.

11. A container made of plastic material formed by reforming an injection molded section in which the container includes a tubular part and an integral part thereof and including a discharge opening or mouth, characterized in that the material of the tubular part is of a thickness which is in the range of between 0.1 and 0.15 millimeters.

12. The container, as claimed in clause 11, characterized in that said tubular part is essentially circular in shape. SUMMARY The invention relates to a method and an apparatus for producing a tubular container made of plastic material, in which the plastic material is supplied to an injection mold and forms therein a section including a section body with a tubular part. The tubular part is open at one end and has, at its other end, the opening or mouth for emptying the future container. The tubular part is displaced through an annular gap under reduction of the thickness of the material and under axial extension. After the extension is completed, the tubular part is cut to the desired length. The apparatus for forming the container comprises an injection molding machine, an injection mold, a pull ring surrounding a mandrel and forming a gap between itself and the mandrel, and drive means for relative movement of the pull ring and the mandrel in the longitudinal direction of the mandrel. The container which is formed includes a tubular part and an integral part thereof and includes a mouth or drain opening. The material in the tubular part is of a thickness in the range of between 0.1 and 0.15 millimeters.