DE102018007610A1 - Plastic container - Google Patents

Abstract

The present invention relates to a container made of thermoplastic material by blow molding - preferably a bung (10) - with welded bung nozzles prefabricated by injection molding with an internal thread for storing and transporting liquid or flowable filling materials of thick spots z. B. to eliminate threaded pegs and pinch seams, a weld bung (32) is formed according to the invention in the upper floor (30) of the container, onto which a solid threaded weld flange (12) with internal thread (20) is welded, which is prefabricated.

Description

The invention relates to a container made of thermoplastic material for the storage and transport of liquid or flowable filling goods, which is produced by the blow molding process and is provided with a welded, pre-fabricated bung nozzle with an internal thread.

Such blow-molded plastic containers are usually L-ring drums in drum sizes from 120 liters to 250 liters. The most common are L-ring drums with a capacity of 220 liters, but others are also on the market. Also known are other plastic containers such. B. 30 or 60 liter canister with bung-top closures. All of these plastic containers are used for the storage and transport of liquid or flowable filling goods and are usually equipped with a larger 2-inch and a smaller ¾-inch bung opening, the larger bung for filling and removing the filling material and the Smaller bung serves as a ventilation bung during the filling and removal process.

In large chemicals, large quantities of such plastic containers are almost only filled in automatic filling systems at the end of the manufacturing process for chemical liquids. The plastic container is positioned so that the bung is always precisely aligned and automatic unscrewing devices can grasp and unscrew the bung. A filling lance then moves into the larger 2-inch bung opening and the liquid filling material is pumped into the container at high filling pressure. After the filling process has been completed, the bung plugs are screwed back into the filler / dispenser spout and the ventilation spout by the automatic boring machine.

• Kunststoff-Behälter mit Spundstopfen werden weltweit in großen Stückzahlen größtenteils im Blasformverfahren hergestellt. Dabei werden die Hohlkörper aus einem extrudierten schlauchförmigen Vorformling zwischen zwei horizontal zusammenfahrbaren Blasformhälften unter Einwirkung von eingeblasener Druckluft zu ihrer endgültigen Form aufgeblasen. Beim Zusammenfahren der beiden Blasformhälften wird der schlauchförmige Vorformling oben und unten abgequetscht und verschweißt. Normalerweise wird der Unterboden des Behälterkörpers oben in der Blasform und der Oberboden des Behälterkörpers mit den Spundöffnungen unten in der Blasform ausgebildet. Mittels verfahrbarer Spreiz- und Blasdorne kann die Länge der Abquetschnaht und die exakte Position der Spundstutzen eingestellt werden. Die Formgebung des Behälterkörper-Unterbodens oben in der Blasform ist vergleichsweise einfach, weil der Unterboden als Standfläche für den Behälterkörper möglichst flach und eben ggfs. mit Versteifungssicken ausgebildet sein soll, während sich die Ausformung des Behälterkörper-Oberbodens mit am Außenumfang umlaufenden Handhabungsring (= sogenannter L-Ring), mit bombiertem oder höher gelegtem Mittelteil und zwei sich diametral gegenüberliegenden in Spundmulden tiefer gelegten Spundstutzen erheblich schwieriger gestaltet. Die besondere Kunst der Blasformtechnik besteht in einer ausgeklügelten Wanddickensteuerung des extrudierten schlauchförmigen Vorformlings, denn am fertigen Behälterkörper soll möglichst überall die gleiche Wanddicke vorliegen. Das ist verfahrenstechnisch nicht ganz möglich, denn an beiden Enden der oberen und unteren Abquetschnaht des schlauchförmigen Vorformlings liegt immer eine Materialverdickung vor. Im Unterboden des Behälterkörpers werden die beiden Materialverdickungen möglichst flach gezogen. Die sich im Oberboden des Behälterkörpers ergebenden Materialverdickungen werden dazu ausgenutzt, an zwei unterhalb der Blasform angeordneten Blasdornen im Behälterkörper-Oberboden zwei Spundstutzen mit Innengewinde auszuformen. Die beiden Spundstutzen sind jeweils in einer Spundmulde bzw. einem Spundgehäuse vertieft im Oberboden angeordnet. Der am Außenumfang des Oberbodens umlaufende L-Ring wird während des Blasformvorgangs mittels vertikal verschiebbarer Formschieber aus dem Kunststoffmaterial des schlauchförmigen Vorformlings angeformt. Nach Beendigung des Blasformvorgangs werden vor Entnahme des fertigen Behälterkörpers aus der Blasform die Blasdorne aus den angeformten Spundstutzen mit Innengewinde herausgeschraubt. Während die vertikale Behälterwandung und der Unterboden des Hohlkörpers vergleichsweise schnell abgekühlt sind, benötigen die Bauteile wie L-Ring und Spundstutzen mit erhöhtem Materialeinsatz verständlicherweise eine höhere Abkühlzeit bis auf Raumtemperatur. Da an den Spundstutzen durch Materialverdickungen auf der einen Seite sowie durch eine einseitig einmündende Quetschnaht auf der anderen Seite und die Nähe des massiven L-Rings nicht in alle Richtungen die gleichen Abkühlbedingungen vorliegen, kann dies als Folge des Blasformens, ggfs. mit Nachkühlung unter Innendruck, zu Materialverzug und Abweichungen der geometrischen Abmessungen führen.

Problem:

• Plastic containers with bung plugs are mostly produced in large numbers worldwide using the blow molding process. The hollow bodies are inflated to their final shape from an extruded tubular preform between two horizontally collapsible blow mold halves under the influence of blown compressed air. When the two blow mold halves move together, the tubular preform is squeezed and welded at the top and bottom. Typically, the bottom of the container body is formed at the top in the blow mold and the top of the container body with the bung openings at the bottom in the blow mold. The length of the pinch seam and the exact position of the bung can be adjusted by means of movable expanding and blowing mandrels. The shape of the container body underbody at the top in the blow mold is comparatively simple, because the underbody as a base for the container body should be as flat as possible and, if necessary, with stiffening beads, while the shape of the container body top with a circumferential handling ring (= so-called L-ring), with a cambered or raised middle section and two diametrically opposed bung supports lowered in sheet pits. The special art of blow molding technology consists in a sophisticated wall thickness control of the extruded tubular preform, because the same wall thickness should be present everywhere on the finished container body. In terms of process engineering, this is not entirely possible, because there is always a thickening of material at both ends of the upper and lower pinch seam of the tubular preform. The two material thickenings are drawn as flat as possible in the underbody of the container body. The material thickenings that result in the upper floor of the container body are used to form two bung nozzles with an internal thread on two blowing mandrels arranged below the blow mold in the upper body of the container body. The two bung supports are each recessed in a bung or a bung housing in the top floor. The L-ring encircling the outer periphery of the top floor is molded from the plastic material of the tubular preform during the blow molding process by means of vertically displaceable mold slides. After completion of the blow molding process, the blow mandrels are unscrewed from the molded bung with internal thread before the finished container body is removed from the blow mold. While the vertical container wall and the underbody of the hollow body have cooled down comparatively quickly, the components such as the L-ring and bung supports with increased use of material understandably require a longer cooling time to room temperature. Since the bung is not the same in all directions due to material thickening on one side and a pinch seam opening on one side and the proximity of the solid L-ring, this can be the result of blow molding, possibly with post-cooling under internal pressure , lead to material distortion and deviations in the geometric dimensions.

Here, z. B. ovalize the bung openings in the bung, so that the seal of a screwed bung plug on the Sealing seat can no longer completely seal and the bung is particularly leaky when a container filled with liquid contents falls over. In addition, disturbing film-like plastic appendages can form on the pinch seam that opens at one end, which have an adverse effect on the seat of the screwed-in bung plug.

On the other hand, the bung can distort itself into a slight inclination, which can later lead to problems in the automatic filling systems when filling such containers if, for. B. the unscrewing machine for the bung plug cannot intervene exactly in the upper recesses in the bung plug for the screw-head tool or the vertically descending filling lances for pressure filling cannot be inserted precisely into the bung openings of the bung. This causes malfunctions in automatic filling plants in large chemicals, which costs time and money and leads to dissatisfied customers.

State of the art:

From the publication EP 0 515 390 B1 a blow-molded sheet drum made of thermoplastic material is known, in which a sheet connection piece, prefabricated by injection molding, is welded into the top floor of the barrel body. The bung has a pipe section with an internal thread that protrudes a bit into the barrel body. This design was chosen because the bung housing is very flat and the top edge of the bung with screwed bung plug should not protrude above the top floor, but should be flush with it. So that there is a sufficient number of threads for a secure fit of the screwed-in bung plug, the bung pipe piece is shifted a bit into the inside of the barrel. In order to enable good residual emptying, the bung pipe piece is provided with a recess or opening on the side facing the L-ring, so that the last drops of residual liquid can flow out of the barrel interior. The welding of the bung pipe piece was realized by build-up welding with the addition of melted plastic material. Due to the lack of suitable welding surfaces, the bung pipe piece cannot be welded in using the mirror welding process.

Task:

• - vorzugsweise nach dem Spiegelschweißverfahren - von separat im Spritzgussverfahren vorgefertigten Spundstutzen mit Innengewinde auf im Blasformverfahren hergestellte Kunststoffbehälter wie Fässer, Kanister und Innenbehälter für Palettencontainer derart vorzuschlagen, dass bei Verwendung von blasgeformten Kunststoffbehältern an vorhandenen Abfüll- und Abpumpanlagen behälterseitig bedingte Störungen nicht mehr auftreten bzw. weitestgehend minimiert werden können.

The present invention is based on the object of eliminating the disadvantages of the prior art outlined above and a possibility for optimal welding

• - preferably using the mirror welding process - to propose from sheet-metal nozzles, separately prefabricated by injection molding, to blow-molded plastic containers such as barrels, canisters and inner containers for pallet containers in such a way that when using blow-molded plastic containers on existing filling and pumping systems, there are no longer any malfunctions caused by the container or can be minimized as far as possible.

Solution:

• - behälterseitig ist eine ringförmige Schweißfläche mit einer kreisförmigen Innenkante und einer kreisförmigen Außenkante vorgesehen,
• - der im Spritzgussverfahren vorgefertigte Spundstutzen ist als massiver Gewindeschweißflansch mit Innengewinde ausgebildet und
• - weist eine korrespondierende ringförmige Schweißfläche mit einer kreisförmigen Innenkante und einer kreisförmigen Außenkante auf, und
• - die beiden ringförmigen Schweißflächen sind stoffschlüssig fest und unlösbar miteinander verbunden.

This object is achieved with the special features of claim 1. The features in the subclaims describe further advantageous design options for the blow-molded container according to the invention with welded-on bung nozzles prefabricated in the injection molding process. The proposed technical teaching conveys in a simple manner how the disadvantages of known blow-molded plastic containers can be overcome, this is achieved in a constructive manner by the following features:

• an annular welding surface with a circular inner edge and a circular outer edge is provided on the container side,
• - The bung, which is prefabricated in the injection molding process, is designed as a solid welded flange with an internal thread and
• - Has a corresponding annular welding surface with a circular inner edge and a circular outer edge, and
• - The two annular welding surfaces are firmly bonded and non-detachably connected.

The spaced-apart inner and outer edges of the welding surfaces result in a flat extension of the annular welding surfaces. The width of the welding surfaces, viewed in the radial direction or obliquely, is between 3 mm and 15 mm, preferably approximately 5 mm, so that in particular the mirror welding method is particularly suitable here. The massive thread welding flange, which is prefabricated in the injection molding process, prevents possible ovalization of the bung opening and the sealing seat for the bung plug and has precisely formed threads with sharp thread flanks. In the area of its largest diameter, the massive thread welding flange has a thickening or accumulation of plastic material with a wall thickness of approximately 6 - 8 mm, which is almost twice as thick as compared to the wall thickness of the tank top with a wall thickness of approx. 3 - 4 mm. Basically could the integral connection of the threaded weld flange with the top of the plastic container in various ways, for. B. by gluing, networking or the like. Preferably, the cohesive connection in the present invention is to be carried out according to the known mirror welding method which is particularly suitable for this purpose, the two welding surfaces being partially melted by applying appropriately shaped, heated welding elements and, after removal of the welding elements, pressed firmly against one another and permanently connected or welded to one another.

In an embodiment of the invention, it is provided that the annular welding surface on the container side and the corresponding annular welding surface on the solid threaded welding flange are designed to be essentially three-dimensionally inclined. The cross-sectional view of the opening in the top of the container enclosed by the annular welding surface has an almost trapezoidal shape. In other words, the opening in the top of the container, which is enclosed by the annular welding surface on the container side, represents an upside-down conical section shape (tip down, base up).

Advantageously, with normal upright positioning of the container, the outer edges of the two welding surfaces lying one on top of the other are arranged higher than the inner edges of the two welding surfaces. Due to this design, the massive thread welding flange can be better centered and vertically aligned during welding.

In a modified embodiment of the invention, the annular welding surface on the container side is essentially concave and the annular welding surface on the threaded welding flange is essentially convex. The adaptation of the two three-dimensional annular welding surfaces to one another enables better centering and alignment of the threaded welding flange when welding into the tank top.

In a preferred modification of the invention it is provided that the outside of the threaded welding flange is dome-shaped at least in the area of its annular welding surface and the container-side annular welding surface has a corresponding negative dome-shaped shape. The dome-shaped design of the ring-shaped welding surfaces of the two parts to be welded is the best way to compensate for unevenness and inclinations in the bottom area of the bung housing or with a slightly convex container top surface, so that a precise vertical alignment of the welded-in threaded welding flange is achieved, which eliminates previous problems and the resulting faults the use of blow-molded plastic containers on existing filling and pumping systems no longer occur.

In the case of a particularly preferred constructional design, the outside of the thread welding flange is almost entirely dome-shaped. The threaded welding flange has the shape of a spherical layer, also called a spherical disc, and is part of a solid sphere that is cut out from two parallel planes. The curved surface part is called the spherical zone and represents the dome-shaped outside of the thread welding flange. The special shape of a spherical dome enables optimal welding conditions and a massive design of the thread welding flange in a decorative design. In the case of blow-molded sheet drums, the plastic material is usually colored blue. The separate production of the thread welding flanges using the injection molding process enables a different color to be selected for the welded thread welding flanges. As a reference to certain products, the prefabricated threaded welding flanges z. B. the color red for dangerous goods containers, the color green for plastic containers with environmentally friendly contents or the color yellow for food-friendly plastic containers.

The compact spherical cap-shaped design of the solid thread welding flange makes it possible in a special way that the annular welding surface on the container side is formed almost without a nozzle directly in the bung opening in the top floor of the container. This can, for. B. the depression of a bung housing or a bung in the top of the plastic container can be kept particularly flat, whereby an improved residual emptying of the plastic container can be accomplished. The direct welding of a threaded welding flange directly into a bung opening in the top floor of a container is particularly suitable for 1000 liter plastic inner containers of pallet containers that do not have a separate bung housing for the bung opening, but only have a lowered central area of the inner container top floor.

Preferably, in the case of sheet drums and canisters, in a constructive embodiment of the invention, the annular welding surface on the container side is formed at the upper edge of a short welding plug connecting piece that surrounds the sheet opening in the upper floor of the container. Appropriately, the welding bung for the common ¾-inch, 2-inch and 3-inch bung closures are each with a standard welding bung identical contour. Then the barrel body or L-ring barrel can be manufactured without changing the blow mandrels in the blow mold for the different bung closures, as it were, as a universal barrel body with reduced-thickness unit weld bung. By reducing changeover times and shortening cooling times, a significant increase in quantities is achieved.

Pre-fabricated standard thread welding flanges in all common thread shapes can then be welded into the standard welding plug connection. If L-ring drums are used in Europe, one bung is usually designed as a 2-inch filling and emptying bung and the other bung as a ¾-inch ventilation bung with a coarse thread, while L-ring drums, which are primarily in the American or Asian market, are equipped with two 2-inch bobbins, in which case one bung is equipped with a coarse thread and the other bung is equipped with a fine thread.

• - es ist möglich in die Universal-Fasskörper einen dünnwandigen Inliner einzusetzen und den dünnwandigen Inliner-Stutzen im zylindrischen Bereich des Einheits-Schweißspundstutzen radial einzuschweißen und erst danach den Gewindeschweißflansch mit beliebigem Gewinde auf den Einheits-Schweißspundstutzen aufzusetzen bzw. aufzuschweißen;
• - die Fertigung der Universal-Fasskörper mit den beiden Einheits-Schweißspund-stutzen kann blasformtechnisch z. B. durch Verkürzung der Zykluszeiten optimiert werden, da das intensive Kühlen der üblichen Gewindeflansche entfällt und auch die Ausdrehzeit der Gewinde-Blasdorne wegfällt;
• - die Wanddicke des schlauchförmigen Vorformlings kann besser gesteuert werden, da das Kunststoff-Material zur Ausformung der Gewinde nicht mehr benötigt wird;
• - ein Werkzeugwechsel (andere Schalen und Blasdorne) beim Wechsel von einer auf eine andere Spundstutzen-Geometrie (Grobgewinde - Feingewinde) entfällt;
• - die Toleranzen der Gewindeflansche können verbessert bzw. minimiert werden, was insbesondere bei dem amerikanischen Feingewinde (NPS 2-Zoll) wichtig ist;
• - die Ovalität der Gewindeöffnung in den Gewindeschweißflanschen wird eliminiert;
• - eine eventuelle Neigung der Einheits-Schweißspundstutzen bezogen auf den Behälteroberboden kann durch die Kalottengeometrie der Gewindeschweißflansche beim Aufschweißen ausgeglichen werden;
• - die Toleranzen der Außengeometrie für die aufzusetzenden Siegelkappen können deutlich enger eingestellt werden;
• - farblich individuell gestaltete Gewindeschweißflansche ermöglichen eine optische Unterscheidung von üblichen standard-blauen L-Ringfässern;
• - als alternative einfachste Schweißgeometrie können auch ebene Schweißflächen realisiert sein.

Numerous advantages can be achieved with the present invention:

• - It is possible to use a thin-walled inliner in the universal barrel body and to weld the thin-walled inliner socket radially in the cylindrical area of the unit welding plug, and only then to attach or weld on the threaded welding flange with any thread on the unit welding plug;
• - The production of the universal barrel body with the two standard weld bung can be blow molding z. B. can be optimized by shortening the cycle times, since the intensive cooling of the usual threaded flanges is omitted and the unscrewing time of the threaded blow mandrels is eliminated;
• - The wall thickness of the tubular preform can be controlled better, since the plastic material for forming the thread is no longer required;
• - a tool change (other shells and blow mandrels) when changing from one to another bung geometry (coarse thread - fine thread) is not required;
• - The tolerances of the threaded flanges can be improved or minimized, which is particularly important for the American fine thread (NPS 2-inch);
• - The ovality of the thread opening in the thread welding flanges is eliminated;
• - A possible inclination of the standard weld bung with respect to the tank top can be compensated for by the calotte geometry of the thread welding flanges during welding;
• - The tolerances of the outer geometry for the sealing caps to be put on can be set much narrower;
• - Threaded, individually designed welding flanges enable a visual differentiation from standard blue L-ring drums;
• - As an alternative simplest welding geometry, flat welding surfaces can also be realized.

• 1 in perspektivischer Ansicht einen erfindungsgemäßen blasgeformten Kunststoff-Behälter in Form eines Spundfasses mit eingeschweißten Gewindeschweißflanschen,
• 2 einen erfindungsgemäßen Gewindeschweißflansch in Querschnittsansicht,
• 3 eine Teilquerschnittsansicht durch einen eingeschweißten Gewindeschweißflansch,
• 4 eine andere Teilquerschnittsansicht durch einen eingeschweißten Gewi ndeschwei ßflansch,
• 5 eine weitere Teilquerschnittsansicht durch einen eingeschweißten Gewindeschweißflansch ,
• 6 in Teilquerschnittsansicht eine andere Ausführungsform eines eingeschweißten Gewindeschweißflansches

The invention is explained and described in more detail below on the basis of exemplary embodiments schematically illustrated in the drawings. Show it:

• 1 a perspective view of a blow-molded plastic container according to the invention in the form of a bung with welded-in welded flanges,
• 2nd a threaded weld flange according to the invention in cross-sectional view,
• 3rd a partial cross-sectional view through a welded threaded weld flange,
• 4th another partial cross-sectional view through a welded-in welding flange,
• 5 another partial cross-sectional view through a welded threaded weld flange,
• 6 in partial cross-sectional view another embodiment of a welded threaded weld flange

In 1 is shown as a preferred embodiment of a blow molded plastic container, a bung made of thermoplastic material and with the reference number 10th designated. Sheet drums with an upper handling ring, the so-called "L-ring", are available in various drum sizes with a filling volume of 30 liters to 300 liters. The most common are 220 liter drums with two bung closures in the top of the drum. According to the invention, the bung closures are each provided with a welded-in threaded weld flange which is prefabricated by the injection molding process 12th provided in the gas and liquid-tight closure of the bung opening 28 the usual bung plugs are screwed in.

A threaded weld flange design according to the present invention is shown in FIG 2nd shown. The threaded welding flanges according to the invention 12th can be made in different sizes. Preferred sizes are ¾ inch, 2 inch, 3 inch thread welding flanges. The threaded welding flanges according to the invention 12th can also be provided with different thread versions, either with a coarse thread and sealing seat arranged below the thread or with a fine thread and sealing seat arranged above the thread. 2-inch thread welding flanges can also be designed with a standard BCS 70 x 6 thread.

The bung or threaded connector, which is prefabricated using the injection molding process, is a solid welded flange 12th with internal thread 20th formed and has an annular welding surface 22 with a circular inner edge 24th and a circular outer edge 26 on. The outside of the threaded weld flange 12th can at least in the area of its annular welding surface 22 be dome-shaped. In a preferred embodiment, the outside of the thread welding flange 12th formed almost dome-shaped. The spherical cap shape of the thread welding flange 12th is through the in 2nd Shown with a dashed circle and has the shape of a three-dimensional spherical layer with a uniformly curved outer spherical zone as a dome-shaped outer side of the threaded welding flange. The height of the annular welding surface 22 is through the arrow H _(K) Are defined.

In 3rd is a thread welding flange 12th in installed condition with a bung 10th shown with all-round L-ring. The one in a bung of the top floor 30th arranged bung opening 28 is from a weld bung 32 enclosed. At the upper edge of the weld bung 32 is an annular welding surface 14 formed with a negative dome-shaped contour that has a circular inner edge at the bottom 16 and a circular outer edge at the top 18th having. The welded thread welding flange 12th With a dome-shaped outside, the annular welding surface accordingly has 22 with a circular inner edge 24th and circular outer edge 26 on. So that is with normal upright positioning of the bung 10th the outer edges 18th , 26 of the two superimposed welding surfaces 14 , 22 arranged higher than the inner edges 16 , 24th of the two welding surfaces 14 , 22 . Due to the comparatively large width of the welding surfaces, which is between 3 mm and 15 mm, preferably approximately 5 mm, in the radial direction or obliquely, the mirror welding method which is particularly suitable is used for the welding process. After the welding process, the two annular welding surfaces are 14 and 22 firmly bonded and permanently connected or welded together.

In 4th is the top of a bung 10th shown, in which the top shelf in exaggerated form 30th - e.g. B. by post-cooling with possibly too high internal pressure - is strongly convex or bulged upwards. As a result, the weld bung is here 32 slightly warped and inclined outwards. Due to the spherical shape of the weld bung 32 can also be used for "sloping" topsoil 30th the internal thread 20th the bung opening 28 be aligned vertically.

Due to the slower cooling of thick spots, in particular along the pinch seams of a plastic hollow body removed from the blow mold after blow molding, distortion can occur due to internal stresses in the material, as a result of which the top surface of the hollow body can sink inwards or downwards. Such a case is in 5 shown in an exaggerated form, with the bung 10th the topsoil 30th has sunk down and the weld bung 32 to the middle of the top floor 30th is inclined. Due to the vertical alignment of the dome-shaped thread welding flange 12th becomes the inclination of the weld bung 32 compensated so that the internal thread 20th in the bung opening 28 with a screwed-in bung plug is precisely aligned for the use of automatic screwing machines and filling lances on automatic filling systems and no more problems arise.

In the context of the present invention, in a simple embodiment, the annular welding surface on the container side 14 and the corresponding annular weld surface 22 on the massive thread welding flange 12th be three-dimensionally inclined. That of the annular welding surface 14 enclosed bunghole 28 in the topsoil 30th of the bung 10th then has an almost trapezoidal shape in cross-sectional view. In a modified form, the annular welding surface on the container side can also be used 14 concave and the annular welding surface 22 on the thread welding flange 12th be convex.

In 6 an embodiment is also shown in which the container-side annular welding surface 14 almost without nozzle directly in the bung opening 28 in the topsoil 30th of the bung 10th is trained. It can also at the top of the bung opening 28 on the top floor 30th a surrounding bead 34 be molded on. As a result, the width of the annular welding surface can - if desired 14 increase. This embodiment is particularly intended for smaller containers, such as canisters or small sheet pans, which have only a shallow or no recessed bung for protecting a bung.

• Die vorliegende Erfindung vermittelt die Lehre, wie die Vorteile der Blasformtechnik - hohe Stückzahlen zu vergleichsweise geringen Herstellungskosten - auf einfache Weise mit den Vorteilen der Spritzgusstechnik - präzise geometrische Abmessungen an Dichtungssitzen und Schraubgewinden - kombiniert werden können.

Conclusion:

• The present invention teaches how the advantages of blow molding technology - large quantities at comparatively low manufacturing costs - can be combined in a simple manner with the advantages of injection molding technology - precise geometric dimensions on seal seats and screw threads.

Reference list

10th

Bung

12th

Threaded welding flange ( 10th )

14

annular welding surface on the container side ( 10th )

16

circular inner edge on the container side ( 14)

18th

circular outer edge on the container side ( 14)

20th

Inner thread ( 12th )

22

annular welding surface on the flange side ( 12th )

24th

circular inner edge on the flange side ( 22 )

26

circular outer edge on the flange side ( 22 )

28

Bung opening ( 30th )

30th

Topsoil ( 10th )

32

Welding plug ( 30th )

34

all-round bulge ( 30th )

H (K)

Welding surface height ( 22 )

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 0515390 B1 [0007]

Claims (10)

Containers made of thermoplastic material for the storage and transport of liquid or flowable fillings, which are manufactured using the blow molding process and provided with a welded-on, pre-fabricated bung nozzle with an internal thread, characterized by the following features, - on the container side is an annular welding surface (14) with a circular one Inner edge (16) and a circular outer edge (18) are provided, - the bung, which is prefabricated by injection molding, is designed as a solid welded flange (12) with an internal thread (20) and - has a corresponding annular welding surface (22) with a circular inner edge (24) and a circular outer edge (26), and - the two annular welding surfaces (14, 22) are firmly bonded to one another and are non-detachable. Container after Claim 1 , characterized in that the container-side annular welding surface (14) and the corresponding annular welding surface (22) on the solid threaded welding flange (12) are essentially three-dimensionally inclined. Container after Claim 1 or 2nd , characterized in that with normal upright positioning of the container (10) the outer edges (18, 26) of the two superimposed welding surfaces (14, 22) are arranged higher than the inner edges (16, 24) of the two welding surfaces (14, 22). Container after Claim 1 , 2nd or 3rd , characterized in that the container-side annular welding surface (14) is concave and the annular welding surface (22) on the solid threaded welding flange (12) is convex. Container after Claim 1 , 2nd , 3rd or 4th , characterized in that the outside of the threaded welding flange (12) is dome-shaped at least in the region of its annular welding surface (22) and the annular welding surface (14) on the container side has a corresponding negative dome-shaped contour. Container after Claim 1 , 2nd , 3rd , 4 or 5, characterized in that the outside of the threaded welding flange (12) is almost entirely dome-shaped. Container after Claim 1 , 2nd , 3rd , 4, 5 or 6, characterized in that the annular welding surface (14) on the container side is formed almost without a nozzle directly in the bung opening (28) in the upper floor (30) of the container. Container after Claim 1 , 2nd , 3rd , 4, 5 or 6, characterized in that the container-side annular welding surface (14) is formed on the upper edge of a welding bung (32) surrounding the bung opening (28) in the upper floor (30) of the container. Container according to one of the preceding Claims 1 to 8th , characterized in that the weld bung (32) for the common ¾-inch, 2-inch and 3-inch bung closures are each designed as a standard weld bung. Container according to one of the preceding Claims 1 to 9 , characterized in that the massive threaded weld flange (12) prefabricated by injection molding has a different color, e.g. B. red as an indication of a filled dangerous goods as the container.

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