METHOD AND APPARATUS FOR CONTROLLING THE TEMPERATURE OF A CONTAINER END PORTION DURING MANUFACTURE

Abstract: The invention provides a method for controlling the temperature of a container end portion during manufacture, said container being filled with a product (11), and comprising a substantially tubular body portion (10) of thin-walled plastic or laminated plastic material and a butt-weldable end-piece (13) at each end of the body portion, whereby a first end-piece is fitted to one end of the body portion and the product (11) is introduced into the container via the open end of the body portion, a second end-piece (13) is introduced into the said open body portion end to an intermediate position where it partially projects into the body portion (10), and the plastic material of the body portion end region and the second end-piece is softened through application of heat energy, characterized in that the end-piece (13), by means of relative displacement between it and the body portion (10), is pressed in to the body portion to its terminal position whilst cooling gas is supplied to the transverse wall (15) of the end-piece (13). The invention also provides an apparatus for carrying out the above method.

Description: TITLE : Method and apparatus for controlling the temperature of a container end portion during manufacture. TECHNICAL FIELD: The present invention relates to a method and apparatus for controlling the temperature of a container end portion during manufacture according to the preambles of claims 1 and 6 respectively. BACKGROUND: Tubes and bottles made from thin-walled plastic or plastic laminated material are used for packaging of, for example, creams, ointments and various other viscous chemical/engineering preparations. Swedish Patent Application 8800548-3 describes an end-piece and a method for manufacturing tubes or bottles by butt-welding an end-piece in both ends of a tubular-shaped body portion of thin-walled plastic or laminated plastic material. The advantage of manufacturing tubes or bottles in this way is that the need to transport bulky empty containers over long distances is avoided. Accordingly the method allows the private packager to produce his own tubes or bottles without comprehensive equipment. The tube or bottle produced according to the above method can be filled with its product via its opening, after which a cap is affixed over the opening with the aid of, for example, screw threads. In many cases, however, it is desirable to provide a container which has been sealed in a controlled environment so that the customer can confirm that the packaging is unopened. This results in enhanced quality, both for the packaging and its contents. During production of such a sealed container it is advantageous that filling with the product occurs between the fitting of the first end-piece, preferably tubularly formed, and the second end-piece. In the method according to said Swedish Patent Application 8800548.3 tubular-shaped body portions are located on a rotary indexing table for movement between various stations. At one station each end-p.iece is introduced into the upper end of a corresponding body portion by a piston to an intermediate position where it partially projects into the body portion. This partially assembled work piece is then moved to the next station where heating energy is supplied to the circumferential end region of the tube and intersecting region of the end piece. Once a temperature is attained at which the material is sufficiently soft, the work piece is advanced to the subsequent station where a piston is reapplied to push the end piece to its terminal position. Rapid cooling of the welding site is then achieved by means of passages within the piston for a cooling fluid. PROBLEM AND SOLUTION: Up until now it has proved impossible to apply the end- piece with the piston in situ during heating since the rim of the end-piece upon which the piston acts is subjected to heating to between 300C - 500C, thereby softening the material and causing it to adhere to the piston. The object of the present invention is thus to provide a method and an apparatus which permits the production of filled containers at a high rate whilst avoiding the above-mentioned problem. This object is achieved according to the invention by a method according to claim 1 and an apparatus according to claim 6. Preferred methods and embodiments of the apparatus according to the invention are given in the respective dependent claims. Since, according to the invention, the abutment means acts on the transverse wall of the end-piece which is not subjected to direct heating, and cooling gas is supplied thereto, there is no tendency for the abutment means to adhere to the end-piece. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will be described in more detail in the following, with reference to the drawings in which Figures 1 and 2 schematically show the application of an end-piece to a tubular body portion in two steps with apparatus according to the invention, and Figure 3 shows the compression of the weld-seam. BEST MODE OF CARRYING OUT THE INVENTION: The flattenable tubular body portion 10 shown in the drawings can be made from a single-layer plastic material or from a laminate comprising a metal foil which provides the body portion with better barrier properties. The body portion can be produced by a foil butt-seam welder or, alternatively, from an extruded tube, cut to the appropriate length. Such body portions normally have a wall thickness well under 1 mm. In the drawings only the upper end of the body portion is shown. The lower part of the body portion is already fitted with an end-piece in the form of, for example, a discharge outlet with cooperating screw cap. The body portion is filled via its open end with a product 11 to a predetermined level which corresponds to the desired quantity for the container. The body portion is now placed vertically with the opening upwards in a cylindrical holder 12 in a (not shown) rotary indexing table which is provided with means for fitting the end- piece in the following sequence of steps. In Figure 1 the end-piece 13 has been partially introduced into the upwardly open body portion end and then advanced one stage to the welding station shown in Figures 1 and 2. The end-piece 13 comprises an insert section 14 which, on the inner end, is provided with a transverse wall 15 and, on the other end, is provided by a U-shaped section 16. The insert section 14 tapers inwardly towards the transverse wall 15. The U-shaped section is provided with a groove that tapers towards the bottom of the U-shaped section. The end-piece can, by way of example, be produced by injection-molding, whereby a barrier foil blank may be included on the inner side or the outer side of the transverse wall 15. The welding station is provided with passages 17 for supplying hot gas via directed openings to the region of the body portion end edge and to the groove in the U- shaped section 16 in order to soften these regions by application of heat to a temperature between about 300 - 500"C. After suitable heating, the holder 12 is displaced upwardly in the welding apparatus so that the end-piece 13 is pressed into the tubular body portion until the rim of the body portion meets with the bottom of the groove, as shown in Fig. 2. A central bell-shaped nozzle head 18 of slightly smaller diameter than the transverse wall 15 serves as an abutment for the endpiece 13. The nozzle head 18 is formed with a substantially flat underside provided with a central recess 19 and a groove 23 which extends circumferentially above the perimeter of the transverse wall 15. A substantially vertical branch conduit 24 for the supply cooling gas opens into the groove 23 and accordingly distributes cooling gas around the perimeter of the transverse wall 15. - ' • A suitable cooling gas can be cold air. Expended cold air flows from the groove 23 via the underside of the nozzle head to the surrounding space 22 from where the utilized cold air and hot gas is drawn from the welding station via passages 25. In this way the temperature of the transverse wall region which is abutted by the nozzle head is controlled thereby preventing adhesion of the nozzle head thereto. Advantageously the underside of the nozzle head may be coated with a "non-stick" material, such as TEFLON. Figure 3 shows the subsequent step of compressing the U- shaped section 16 whilst still soft so that a seal in this region is achieved. Compression can be carried out by a vertically displaceable abutment 26 and a plurality of horizontal compression devices 27. These compression devices may be mechanically or elastic-hydraulically operabl . The invention is not restricted to the above described embodiments, but may be modified within the scope of the appended claims.

Claims: Claims 1. Method for controlling the temperature of a container end portion during manufacture, said container being filled with a product (11) , and comprising a substantially tubular body portion (10) of thin-walled plastic or laminated plastic material and a butt-weldable end-piece (13) at each end of the body portion, whereby a first end-piece is fitted to one end of the body portion and the product (11) is introduced into the container via- the open end of the body portion, a second end-piece (13) is introduced into the said open body portion end to ' an intermediate position where it partially projects into the body portion (10) , and the plastic material of the body portion end region and the second end-piece is softened through application of heat energy, characterized in that the end- piece (13) , by means of relative displacement between it and the body portion (10) , is pressed in to the body portion to its terminal position whilst cooling gas is supplied to the transverse wall (15) of the end-piece (13) . 2. Method according to claim 1, characterized in that the heat energy is provided by a hot gas. 3. Method according to claim 1 or 2, characterized in that the cooling gas is cold air. 4. Method according to claim 1, 2 or 3, characterized in that utilized hot gas and cooling gas is removed from the weld region by suction means (25) . 5. Method according to any of claims 1 to 4, characterized in that the weld seams between the tubular body portion (10) and end-piece (13) are subjected to pinching together. 6. Device for controlling the temperature of a container end portion during manufacture comprising an application device for placing an end-piece (13) in a defined intermediate position, partially projecting into an end of a tubular body portion (10) , a heating device (17) for supplying warm gas to soften the plastic material of the body portion end region and the end or ends of the outwardly projecting " portion of the end-piece (13), and means (12, 18) for displacing the body portion and the end-piece relative to each other until the end-piece is in its terminal position in the body portion, characterized by means (24) for supplying a cooling gas to an endwall (15) of the end-piece. • 7. Device according to claim 6, characterized in that the cooling gas is supplied to the transverse wall (15) via a substantially vertical conduit (24) which diverges into a bell-shaped nozzle-head (18) of slightly smaller diameter than the diameter of the transverse wall (15) and which nozzle head (18) has a circumferential slot which opens into a ring-shaped groove (23) which runs above, and substantially around, the perimeter of the transverse wall (15) , the nozzle head (18) also acting as an abutment member for the end-pice. 8. Device according to claim 6 or 7, characterized in that suction means (25) are provided to remove utilized cooling gas from the end wall (15) and hot gas from the weld region.

Inventors: LINNER HANS, LINNER, HANS
Applicants: NORDEN PAC DEV AB, NORDEN PAC DEVELOPMENT AB
Application year: 1991
Main classification: B65B51
IPC codes: B29C57, B29C65, B29C67, B65B7, B65B31, B65B51