This invention relates to a heating device for heating an outwardly facing surface portion of a flange of a pour spout fitment, or of an external surface of a container, and to a method of heating that surface portion.

It is well known to render tacky an axially outwardly facing, annular surface portion of a flange of a plastics pour spout fitment and/or an annular portion of an external surface of an external plastics coating of a wall of a carton, by heating the same in any one of a variety of ways, one of which is by hot air. That annular portion of the external surface of the coating encircles, in one case, a pouring hole, or in another case, the location of an intended pouring hole (which may be bounded by a partial depth cut) through the wall. The subsequent bringing together of the annular surface portion of the flange and the annular portion of the external surface of the coating results in firm sealing of the fitment to the wall. In the other case mentioned above, it is also known for the fitment to include a plunger which has a sharp, often toothed, often annular, inner end which pieces through the above-mentioned location to form the hole, upon rotating of a screw cap of the fitment, or upon manual pressing inwards of the plunger.

WO2009140744 A1 discloses an apparatus for welding, to the inside surface of a tube body, bottle body, or box body, an axially inner rim of a head incorporating an externally threaded pour spout. During the welding operation, that end zone of the body receiving the head is curved inwards onto an outer annular part of the external surface of the head. The apparatus serves to improve the quality of the weld and gives low reject percentages. It has a mandrel on which the head and the body are placed, as well as a cooling element and a nozzle both coaxial with the mandrel. The nozzle comprises two tubular parts - internal and external - which form between them a channel for feeding heating gas. The channel is co-axial with the mandrel and diverges outwardly in the direction of the mandrel so as to heat the head and foil of the body in an annular recess between the head and the aforementioned end zone of the body before that end zone is curved inwards and applied to the head. The apparatus consists of only one work station. The cooling element serves also as a forming element for that end zone and consists of a cooling metal ring located in a forming metal ring. There is a heat-insulating ring between the latter and the cooling metal ring. In the condition of heating, the heat-insulating ring encircles that end zone.

US3783029A discloses an adaptor for a flameless heat tool and comprising a housing defining an outwardly diverging interior chamber and detachably mountable over the exit nozzle of the tool. Supported within the chamber is a baffle member for establishing an annularly shaped outwardly diverging flow of the heated compressed air exiting from the nozzle and the chamber. The baffle includes a part axially extending from the chamber and beyond the housing, which part is adapted to extend into and close a work surface opening whereby the annularly shaped flow of hot air exiting from the housing is directed against an annular portion of the work surface surrounding the opening and heat is excluded from the opening. The adaptor is especially useful in connection with flameless heat tools for applying heat-melt fasteners to laminated panels. Such fastener may comprise an externally flanged, internally threaded, hollow metal tube closely receiving externally a complementary, externally flanged, hollow plastics ring whereby the metal tube is adhered to the panel.

According to one aspect of the present invention, there is provided a heating device for heating an annular, outwardly facing surface portion of (i) a flange of a pour spout fitment comprising a flanged pour spout whereof the flange is to be sealingly applied to an external surface of a container, and a toothed, tubular plunger whereof a toothed edge extends to substantially radially inwards of said flange, or (ii) an external surface of a container formed with a partial-depth cut encircled by said surface portion, said heating device comprising an annular heat-emitting arrangement for locating substantially co- axially of said flange or said cut and serving to direct heating medium obliquely outwardly to impinge upon said outwardly facing surface portion rather than upon said toothed edge or said cut.

According to a second aspect of the present invention, there is provided a method comprising heating an annular, outwardly facing surface portion of (i) a flange of a pour spout fitment whereof a toothed, tubular plunger has a toothed edge which extends to substantially radially inwards of said flange, or (ii) an external surface of a container formed with a partial-depth cut encircled by said surface portion, said method comprising directing heating medium obliquely outwardly to impinge upon said outwardly facing surface portion rather than upon said toothed edge or said cut.

Owing to the invention, it is possible relatively to reduce heating of the toothed edge of the plunger, which might distort or otherwise damage the same and thereby render it less suited to cutting through the packaging material of a container to which the fitment is to be attached, or, where there is a barrier foil closing the inner end of the pour spout, cutting through that foil. It is also possible relatively to reduce heating of one or more barrier layers beneath the cut, which might otherwise damage the barrier layer(s) and thereby reduce the barrier effect. The cut may be in the form of a closed loop, in particular a circle, but is preferably an open loop.

There may be provided two such heating devices, one for the surface portion of the flange and the other for the surface portion of the container.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which:-

Figure 1 shows an axial section through a heating device heating an outwardly facing surface of a flange of a pour spout fitment;

Figure 2 shows an axial section through a heating device heating an external surface of a container; and

Figure 3 is a perspective view of the device of Figure 2.

Referring to Figure 1 , the heating device comprises a supply of hot air (not shown) and a nozzle 2 of circular cross-section with a hot air outlet in the form of a ring of holes 4 co-axial with the nozzle. The holes 4 each extend in an axial plane of the nozzle 2 and are directed obliquely outwardly, so as to emit jets of hot air, as indicated by the arrows 6. Thermoplastics pour spout fitments which are identical to each other and of which one is shown and referenced 8 are presented one after another to the nozzle 2 so as to be located substantially co-axially with the nozzle. Each pour spout fitment consists of three parts, namely a screw cap 10 with a tamper-evident band 12, a pour spout 14 with an annular flange 16, and a tubular plunger 18 with a toothed cutting edge 20 with teeth 22 of which points are located substantially radially inwards of the flange 16. Upon unscrewing of the cap 10, driving projections thereon engage with abutments on the plunger 18 to cause the same to turn about the axis of the fitment 8 and, owing to helical threading 24 between the plunger 18 and the pour spout 14, to cause the plunger to advance helically so that the teeth 22 pierce packaging material of a carton to which the fitment 8 has been applied. In order to attach the fitment 8 to the carton, the outwardly facing annular surface 26 of the flange 16 is first rendered tacky by application of the hot air jets 6 thereto, as shown in the Figure. As can clearly be seen from the Figure, owing to the obliquity of the jets 6, the hot air tends not to reach the teeth 22, so avoiding heating of the thermoplastics teeth, which would tend to distort them, thus to make them less sharp, with the disadvantage of reducing the cutting performance of the teeth on the packaging material.

Referring to Figure 2, the heating device again comprises a supply of hot air (not shown), with a nozzle 32 of circular cross-section with a hot air outlet in the form of a ring of holes 34 co-axial with the nozzle. Again, the holes 34 each extend in an axial plane of the nozzle 32 and are directed obliquely outwardly, so as to emit jets of hot air, as indicated by the arrows 36. Substantially rectangular, inclined, roof sub-panels which are identical to each other and of which one is shown fragmentarily and referenced 38 and which belong to respective gable-topped cartons are presented one after another to the nozzle 32 so that respective open-loop-form, partial-depth cuts of which one is seen and referenced 40 are located substantially co-axially with the nozzle 32. In the instance shown, the gable-topped carton has been made from a laminate consisting of innermost and outermost, thermoplastics, moisture barrier layers 42 and 44 of, for example, low density polyethylene (LDPE). Sandwiched between those layers is a paperboard substrate 46 and an oxygen barrier layer 48 of, for example, ethylene vinyl alcohol (EVOH). The nozzle 32 has a flange 50 formed with through holes 52 whereby the nozzle 32 may be fixed in position. Prior to attaching the fitment 8 to the sub-panel 38, an external annular surface portion of the sub-panel 38 encircling the partial-depth cut 40 is first rendered tacky by application of the hot air jets 7 thereto, as shown in Figure 2. As can clearly be seen from the Figure, owing to the obliquity of the jets 36, the hot air tends not to reach the partial depth cut 40, so avoiding heating of the parts of the layers 44 and 48 therebeneath, which would tend to damage those parts, if not burn holes therethrough.