Method and device for producing a two-chamber tube

The invention relates to a method for producing a two-chamber tube with a dividing wall (9) that extends into the tube head. This method comprises the following steps: a) inserting a dividing wall (9) into the gap (8) of an auxiliary mandrel (6); b) sliding a prefabricated tube pipe body (11) onto said auxiliary mandrel (6), which has been fitted with the dividing wall (9); c) axially transferring the blank (12) produced in step b) from the auxiliary mandrel (6) onto a pressing mandrel (2); d) adding a molten portion of a plastic material in a female mold (3); e) conveying the pressing mandrel (2) with the blank (12) into the female mold (3) with the portion of a plastic material in an axial position, in order to mold a tube head onto the blank (12); f) pressing the material portion between the pressing mandrel 92) and the female mold (3) in order to form a tube head, at the same time producing a solid connection with the pipe body (11) and with the section of the dividing wall (9) that is located in the area of the tube head by closing the mold; g) opening the mold, removing the pressing mandrel (2) and withdrawing the finished two-chamber tube. The invention also relates to a device for carrying out the method.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. 119 of German Application No. 199 11 729.2 filed Mar. 16, 1999. Applicants also claim priority under 35 U.S.C. 120 of PCT/EP00/02291 filed Mar. 15, 2000. The international application under PCT article 21(2) was not published in English.

BACKGROUND OF THE INVENTION

The invention relates to a process for producing a dual chamber tube and to an apparatus for carrying out the process.

1. Field of the Invention

Processes and apparatuses of this type are known, for example, from DE-C1-196 40 833 and from DE-C1-197 12 736.

2. The Prior Art

With the process known from DE 197 12 736 using the apparatus described therein, a partition has to be introduced into a narrow sharp-edged slot in a single-part mandrel, and this can lead to considerable problems, particularly in the case of thin partitions. The performance of the apparatus is greatly restricted as both the production of a tube body with partition and the moulding-on of a tube head which involves cooling times take place in the same apparatus, and different periods of time which affect the rate to be maintained are required in each case.

A two-part pressing mandrel of which the parts are displaceable relative to one another is used with the process known from DE 196 40 833 and the associated apparatus, so the insertion of a tube body provided with a partition is simplified.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a process and an apparatus for producing dual chamber tubes which allows a high speed and a reliable, simple supply of partitions for producing prefabricated tube bodies provided with a partition, in the form of blanks, and the conveyance thereof onto a pressing mandrel and into a mould for the moulding-on of a tube head.

This object is achieved with a process having the features of claim 1 and an apparatus having the features of claim 5.

The associated sub-claims relate to advantageous developments of the invention.

DETAILED DESCRIPTION

The apparatus shown in FIGS. 1 and 2 comprises a turntable 1 which is driven intermittently with pivotal pressing mandrels 2 of the type described, for example, in DE-AS 28 42 515, distributed round the periphery. Each pressing mandrel 2 is arranged so as to pivot into a horizontal and a vertical position. In its vertical position each pressing mandrel 2 is associated with an axially aligned mould 3 on the turntable 1 , pressing mandrel 2 and mould 3 being arranged movably relative to one another in their axial alignment to perform a pressing operation. One mould 3 of the turntable 1 , preferably in a position where the corresponding pressing mandrel 2 is guided horizontally, is associated with a supply station 4 for delivering a portion of a molten plastics material into the mould 3 . The supply station can comprise an extruder and a dispenser.

A hub 5 is arranged so as to rotate intermittently in an axial direction relative to a pressing mandrel 2 located in a horizontal position. The hub 5 carries auxiliary mandrels 6 which preferably but not necessarily each consist of two auxiliary mandrel parts 7 , 7 and have a gap 8 into which a partition 9 in the form of a cut-to-size piece can be inserted. In the embodiment, four auxiliary mandrels 6 distributed uniformly round the periphery of the hub 5 are arranged in a horizontal and axial orientation perpendicular to the axis of rotation of the hub 5 . Each auxiliary mandrel 6 axially aligned in a position on its path round the hub 5 is associated with a pressing mandrel 2 of the turntable 1 , the respective free ends of auxiliary mandrel 6 and pressing mandrel 2 being spaced only slightly from one another in this position.

According to FIG. 1 , a partition 9 is supplied to an auxiliary mandrel 6 at the station I, the partition 9 comprising lateral wings 10 which project from the auxiliary mandrel 6 on either side and are moulded onto the wall of the auxiliary mandrel 6 or in optionally provided recesses corresponding to the wings 10 . At the next station II, a prefabricated tube body 11 is supplied and pushed axially onto the auxiliary mandrel 6 with the inserted partition 9 and the moulded-on wings 10 .

It is also possible to wrap a cut-to-size piece for a tube body round the auxiliary mandrel 6 and to join, for example to weld, an overlapping edge or also, for example, to stick the lateral edges with a sealing tape.

At the subsequent station III, the wings 10 can if necessary be fastened tightly in the tube body, for example by high-frequency welding (the auxiliary mandrels having metal parts at the appropriate points for producing the welding heat in this case). If desired, welding can be carried out over the entire length of contact between tube body 11 and partition 9 or partition wings 10 .

In the last station IV, the blank 12 consisting of tube body 11 with partition 9 produced in station III is transferred to the empty pressing mandrel 2 of the turntable 1 associated with this station in the axial position in each case. To allow the transfer, the auxiliary mandrels 6 at least in station IV are associated with retractable applicators 13 (indicated schematically in FIG. 2 ). The applicator 13 has the object of transferring (applying) the blank 11 from the auxiliary mandrel 6 to the pressing mandrel 2 , and this can also be associated with any auxiliary mandrel 6 .

Preferably, the pressing mandrels 2 as described in DE 196 40 833, to which explicit reference will be made to avoid repetition are also produced in two parts with a parting gap 14 in-between, the two mandrel parts 2 a, b being longitudinally displaceable relative to one another.

The transfer takes place as shown in detail in FIG. 3 . FIG. 3 a shows the starting position in which a blank 12 is to be transferred from the auxiliary mandrel 6 to the pressing mandrel 2 aligned axially opposite with spacing. As shown particularly clearly in FIG. 3 a , the lower auxiliary mandrel part 7 is provided with a recess 15 and the upper auxiliary mandrel part 7 with an insert 16 with a projecting nose 17 . Insert 16 and nose 17 can also be formed integrally with the upper auxiliary mandrel part 7 . The two auxiliary mandrel parts 7 , 7 are bevelled in the entry region of the gap 8 and form a tapering entry funnel to allow easier entry of a partition 9 (see station I) into the gap 8 . Prior to transfer of the blank 12 onto the pressing mandrel 2 , the lower pressing mandrel part 2 a is driven out or positioned into the recess 15 in the auxiliary mandrel 6 , as shown in FIG. 3 b , i.e. they are coupled to one another. The recess 15 is adapted in shape to the leading end of the pressing mandrel part 2 a . This allows an exactly aligned coupled connection between auxiliary mandrel 6 and pressing mandrel 2 .

As shown in FIG. 3 a , the parting gap 14 in the pressing mandrel 2 consists of at least two portions, a leading narrow portion 18 and a trailing broader portion 19 . The internal width of the leading narrow portion 18 corresponds roughly to the thickness of the partition 9 used. The advance of the lower part 2 a of the pressing mandrel 2 (see FIG. 3 b ) not only allows coupling but also simplifies insertion into the parting gap 14 . The coupling to the lower auxiliary mandrel part 7 and the enlargement of the entry gap achieved by the displacement (lifting of the narrow portion 18 ) as well as the guide nose 17 allow reliable, disturbance-free entry of the partition 9 of the blank 12 into the parting gap 14 of the pressing mandrel 2 (see FIG. 3 c ).

Transfer is effected by application of the blank 12 onto the pressing mandrel 2 by means of the applicator 13 . To allow complete application of the blank 12 onto the pressing mandrel 2 , the applicator 13 can be designed to travel out accordingly. However, it is also possible to end the application operation by the applicator 13 in the position shown in FIG. 3 d and then to fix the blank 12 (the tube body 11 ) on the lower pressing mandrel part 2 a , for example to load it with vacuum so that it is held securely and then to convey it into the position shown in FIG. 3 e with the retraction of the pressing mandrel part 2 a into its end position.

At an adjacent station or distributed over a plurality of stations on the turntable 1 , a tube head is moulded on after the pressing mandrel 2 with the blank 12 has been pivoted into an axial position to a mould 3 and its insertion into the mould 3 , and cooling and/or subsequent pressing may be carried out in further clocked positions. A retraction and then pivoting of the pressing mandrel 2 from the vertical position back into a horizontal position is also provided at a station, and the finished dual chamber tube can also be retracted from the pressing mandrel 2 at this station. If other operations, for example the screwing or pushing on of a closure cap, are proposed, a station can also be provided for this on the turntable 3 . Individual steps can optionally also be distributed over a plurality of stations.

A hub 5 with four auxiliary mandrels 6 which are arranged at right angles to one another and are rotatable in a horizontal plane and a turntable 1 with eight pressing mandrels 2 uniformly distributed round the periphery is used in the embodiment, but any other desired number is also feasible, providing that the timing of the hub 5 and of the turntable 1 allows axial alignment of an auxiliary mandrel 6 , equipped with a blank 12 , with an empty pressing mandrel 2 . Conveyors, for example chains or star wheels, on which the pressing mandrels are merely axially displaceably but not pivotally arranged and can be supplied to the individual transfer or processing stations, can also be provided instead of a turntable 1 with pivotal pressing mandrels 2 .