DEVICE FOR WELDING PLASTIC FILMS BY MEANS OF HOT GAS

Abstract

The invention relates to a device for the preferably continuous welding of plastic films by means of hot gas with at least one tubular body through which an electric current flows for the heating of the hot gas, wherein the device comprises at least one gas inlet opening (6, 106) and a plurality of gas outlet openings (12, 112) arranged next to each other, from which hot gas is blown onto the plastic film. It is provided that the at least one gas inlet opening (6, 106) is provided on a main tubular body (4, 104), which stands in gas communication with a plurality of branch tubular bodies (8, 108) at branching points (10, 110), wherein the branch tubular bodies (8, 108) each have at least one gas outlet opening (12, 112) and all the branch tubular bodies (8, 108) have electric current flowing through them.

Claims

1. A device for the welding of plastic films by hot gas with at least one tubular body through which an electric current flows for the heating of the hot gas, wherein the device comprises at least one gas inlet opening (6, 106) and a plurality of gas outlet openings (12, 112) arranged next to each other, from which hot gas is blown onto the plastic film, characterized in that the at least one gas inlet opening (6, 106) is provided on a main tubular body (4, 104), which stands in gas communication with a plurality of branch tubular bodies (8, 108) at branching points (10, 110), wherein the branch tubular bodies (8, 108) each have at least one gas outlet opening (12, 112) and all the branch tubular bodies (8, 108) have electric current flowing through them.

2. The device as claimed in claim 1, characterized in that the branch tubular bodies (8, 108) are substantially identical in shape.

3. The device as claimed in claim 1, wherein the branch tubular bodies (8, 108) and/or the main tubular body (4, 104) form a pressure reservoir.

4. The device as claimed in claim 1, wherein the branching points (10, 110) which connect the main tubular body (4, 104) to the branch tubular bodies (8, 108) are disposed in a circumferential wall of the main tubular body (4, 104).

5. The device as claimed in claim 1, wherein the plurality of branch tubular bodies (8, 108) are arranged substantially parallel with each other.

6. The device as claimed in claim 1, wherein the at least one gas outlet opening (12, 112) of a branch tubular body (8, 108) has a substantially round, oval or slot-like cross section.

7. The device as claimed in claim 1, wherein the branch tubular bodies (8, 108) have a curved shape, wherein the branch tubular bodies (8, 108) in particular are arranged curved in a spiral around the main tubular body (4, 104).

8. The device as claimed in claim 1, wherein the branch tubular bodies (8, 108) through which electric current is flowing are electrically connected in series.

9. The device as claimed in claim 1, wherein the plurality of branch tubular bodies (8, 108) through which electric current is flowing are electrically connected in parallel.

10. The device as claimed in claim 1, wherein the device has a modular design, wherein each module (124) has at least one branch tubular body (8, 108), through which electric current is flowing, with at least one gas outlet opening (12, 112), at least one branching point (10, 110) and at least one section (126) of the main tubular body (4, 104).

11. The device as claimed in claim 10, characterized in that several modules (124) are connected together, wherein at least one connection element (136) is provided, which joins together at least two modules (124) each time.

12. The device as claimed in claim 11, characterized in that the connection elements (136) form an electrical circuit with the respective branch tubular bodies (8, 108) of the modules (124).

13. The device as claimed in claim 10, characterized in that each module (124) has an electrical insulation layer (130).

14. The device as claimed in claim 10, characterized in that at least one end module (138) is provided.

Description

[0048] Further features, details and benefits of the invention will emerge from the wording of the claims as well as the following description of exemplary embodiments with the aid of the drawings. There are shown:

[0049] FIG. 1 a schematic cross-sectional view of a device according to the invention,

[0050] FIG. 2 a schematic cross-sectional view of one embodiment of a branch tubular body,

[0051] FIG. 3 a schematic side view of the branch tubular body in FIG. 2,

[0052] FIG. 4 a perspective view of a module to construct a device according to the invention,

[0053] FIG. 5 a perspective side view of a modular design embodiment of a device according to the invention,

[0054] FIG. 6 a perspective cross-sectional view of the embodiment shown in FIG. 5,

[0055] FIG. 7 an exploded representation of the embodiment of a modular design device according to the invention as shown in FIG. 5 and FIG. 6.

[0056] FIG. 1 shows a device 2 according to the invention with a main tubular body 4 with a gas inlet opening 6. The main tubular body 4 stands in gas communication with a plurality of branch tubular bodies 8 at branching points 10. The branch tubular bodies 8 each have at least one, especially exactly one, gas outlet opening 12.

[0057] The branch tubular bodies 8 receive a flow of electric current, by which they become heated. The gas flowing through them takes up the heat and is blown as hot gas onto a plastic film moved at a distance from the gas outlet openings 12. That is not shown here.

[0058] FIG. 1 shows a series circuit of the branch tubular bodies 8, wherein each time a branch tubular body end 14 of one branch tubular body 8 is electrically connected to a branch tubular body beginning 16 of the neighboring branch tubular body 8b. In this way, the branch tubular body 8 receives a flow of current over almost its entire length, so that the gas can be heated in the best possible way.

[0059] Preferably, the electrical contacts 18 are arranged each time at opposite ends of the respective branch tubular body 8. In this way, the flow path of the gas in the branch tubular body 8 can be used for the heating of the gas in the best possible way.

[0060] In FIG. 1, the gas inlet opening 6 is arranged at an end face 20 of the main tubular body 4. The opposite end 22 of the main tubular body 4, situated opposite the gas inlet opening 6, is shown here closed off, although other embodiments are also possible.

[0061] FIG. 2 and FIG. 3 show another embodiment of the branch tubular bodies 108. Here, the branch tubular body 108 is curved, in particular wound in a spiral. Preferably, the branch tubular body 108 in this embodiment is curved around the main tubular body 104, although the main tubular body 104 is not represented in FIGS. 2 and 3.

[0062] FIG. 2 shows a cross-sectional view through the branch tubular body 108. FIG. 3 on the other hand shows a side view of the same branch tubular body 108. In both FIGS. 2 and 3 the gas flows from the main tubular body 104 across the branching points 110 into the branch tubular body 108. These receive a flow of electric current and heat the gas flowing through them. The hot gas emerges through the gas outlet openings 112 of the respective branch tubular body 108 and is blown onto the plastic film being welded. The emerging hot gas is indicated by an arrow. In the embodiment shown here, the branching point 110 and the gas outlet opening 112 are arranged at the respective end faces of the opposite ends of the branch tubular body 108, but other arrangements are also possible.

[0063] These curved branch tubular bodies 108 shown in FIGS. 2 and 3 may be used in a permanently mounted device 2, as shown for example in FIG. 1, and in a modular design device 102.

[0064] FIG. 4 shows a schematic representation of a module 124 with at least one branch tubular body 108 receiving a flow of electric current with at least one gas outlet opening 112, at least one branching point 110 and at least one section 126 of the main tubular body 104.

[0065] The branch tubular body 108 has two poles, so that it can receive a flow of current. The one pole is formed by the circumferential wall 128 of the section 126 of the main tubular body 104 and stands in electrical contact with the branch tubular body beginning 116; the other pole is arranged as an electrical contact 118 in a region of the branch tubular body end 114.

[0066] In order to make possible a series circuit, each module 124 has an insulation layer 130, which in each case electrically separates the two poles from each other.

[0067] In the embodiment shown, two additional recesses 132 are provided in the circumferential wall 128 of the section 126 of the main tubular body 104. These may serve for the connecting of several modules 124.

[0068] FIG. 5 shows a schematic representation of a top view of one embodiment of a modular design device 102. Here, several of the modules 124 represented in FIG. 4 are joined together.

[0069] The main tubular body 104 comprises a gas inlet opening 106 at one end and an opposite closed end 122. The main tubular body 104 receives a flow of gas and is connected to a plurality of branch tubular bodies 108 at branching points 110. The branch tubular bodies 108 are curved in a spiral around the main tubular body 104. The gas flows through the gas inlet opening 106 into the main tubular body 104 and is divided at the branching points 110 among several branch tubular bodies 108. In the branch tubular bodies 108, which receive a flow of electric current, the gas is heated and blown as hot gas through the respective at least one gas outlet opening 112 onto the plastic film being welded. The hot gas is shown symbolically by arrows.

[0070] In the embodiment represented in FIG. 5, the branch tubular bodies 108 are joined together in an electrical series circuit. The poles are arranged as described above. The first pole is formed by the circumferential wall 128 of a section 126 of the main tubular body 104. The second pole at the branch tubular body end 114 is electrically connected to the circumferential wall 128 of an adjacent section 126b of the main tubular body 104 of an adjacent module 124. Between the sections 126, 126b of the main tubular body 104 there is provided each time an electrical insulation layer 130.

[0071] In the embodiment shown here, the device 102 is mounted on a plate 134, which may serve for the fastening of the device 2 inside a layout and/or the temperature shielding of the device 2 against other components of the layout.

[0072] FIG. 6 shows a cross-sectional view of the embodiment of the device 102 according to the invention represented in FIG. 5.

[0073] In the modular design embodiment of the device 102 according to the invention as represented in FIGS. 5 and 6, several modules 124 are joined together.

[0074] Thus, the modules 124 for example may be mounted on connection elements 136, especially in the form of rods, as shown in FIG. 7.

[0075] FIG. 7 shows a schematic exploded representation of the embodiment of a modular design device 102 as represented in FIG. 5 and FIG. 6.

[0076] Here, several of the modules 124 represented in FIG. 6 are joined together. The modules 124 are pushed onto connection elements 136 in the form of rods, the connection elements 136 being arranged in the recesses 132. The section 126 of the main tubular body 104 of a first module 124b acts as the gas inlet opening 106. An end module 138 closes off from the outside in a gas-tight manner the main tubular body 104, formed by the sections 126 of the main tubular body 104 of the modules 124. This end module 138 in the embodiment represented is arranged at the end 122 of the main tubular body 104 situated opposite the gas inlet opening 106. A fastening of the end module 138 to the connection elements 136 in the form of rods occurs with the aid of nuts 140.

[0077] The device 102 in FIG. 7 has a plate 134. Furthermore, additional fastening means are represented in the form of screws, which can fasten the device 102 in a plastic film welding layout.

[0078] The invention is not limited to one of the above-described embodiments, but rather may be modified in various ways.

[0079] All of the features and benefits emerging from the claims, the description and the drawing, including structural details, spatial arrangements and method steps, may be essential to the invention both in themselves and also in the most diverse combinations.

LIST OF REFERENCE NUMBERS

[0080] 2, 102 Device [0081] 4, 104 Main tubular body [0082] 6, 106 Gas inlet opening [0083] 8, 108 Branch tubular body [0084] 10, 110 Branching points [0085] 12, 112 Gas outlet openings [0086] 14, 114 Branch tubular body end [0087] 16, 116 Branch tubular body beginning [0088] 18, 118 Electrical contact [0089] 20, 120 End face of main tubular body [0090] 22, 122 Opposite end of main tubular body 4 [0091] 124 Module [0092] 124b First module [0093] 126 Section of main tubular body 104 [0094] 126b Adjacent section of main tubular body 104 [0095] 128 Circumferential wall of section 126 of main tubular body 104 [0096] 130 Insulation layer [0097] 132 Recesses [0098] 134 Plate [0099] 136 Connection elements [0100] 138 End module [0101] 140 Nut