METHOD FOR CONNECTING TWO JOINING SURFACES

Abstract

The cutting of fibrous material which does not melt easily is effected to avoid the unravelling of cut edges, using ultrasonic or laser beam techniques. The method includes (a) applying a thermoplastic powder material to the cutting region, and (b) applying thermal shock to the localised area, sufficient to destroy the fibres of the material, and melt the powder on either side of the cut, and (c) pressing the cut edges while the fused thermoplastic powder is still soft. Woven or non-woven fabrics have tendency to unravel, after cutting, and normally require a sewn hem. The method of the invention disposes of the sewn hem, and provides a thermo-cutting technique applicable to non-fusible or non-thermoplastic fibres.

Claims

1. A method for connecting a first joining surface of a first workpiece (3) to a second joining surface of a second workpiece (4), said method having the steps of: 1) bringing the first and the second joining surfaces into contact with each other, 2) bringing a first tool part (1) into contact with the first workpiece (3) and introducing energy into the first workpiece (3) via the first tool part (1), characterised in that before step 1) a step of: A) applying particles (5) formed from thermoplastic material to the first and/or second joining surface is performed and, during step 2), the particles (5) formed from thermoplastic material are melted and the first and second joining surfaces are connected to one another.

2. The method according to claim 1, characterized in that, at the same time as step 2), the step of: 3) bringing a second tool part (2) into contact with the second workpiece (4) is performed.

3. The method according to claim 1, characterized in that at least one workpiece (3, 4) does not consist of a thermoplastic material.

4. The method according to claim 1, characterized in that at least one workpiece (3, 4), consists of a fibrous material or a porous material.

5. The method according to claim 1, characterized in that, before step 1): B) introduction of depression into the first and/or second joining surface is performed.

6. The method according to claim 1, characterized in that, after step 2): 3) removal of thermoplastic particles (5) not melted together with the first or second joining surfaces is performed.

7. The method according to claim 1, characterized in that the thermoplastic particles (5) are sphere-shaped, fibre-shaped, or platelet-shaped.

8. The method according to claim 1, characterized in that both the first workpiece (3) and the second workpiece (4) are strip-shaped.

9. The method according to claim 1, characterized in that, during step 2), energy is introduced into the first workpiece (1) by vibrating the first tool part (3) with an ultrasonic vibration.

10. The method according to claim 11 characterized in that, during step 3), the second tool part (2) is vibrated with an ultrasonic vibration.

11. The method according to claim 2, characterized in that, during step 2), energy is introduced into the first workpiece (1) by vibrating the first tool part (3) with an ultrasonic vibration.

12. The method according to claim 3 wherein both workpieces do not consist of a thermoplastic material.

13. The method according to claim 4, characterized in that both workpieces, consist of a fibrous material or a porous material.

14. The method according to claim 5, wherein step B) is performed before step A).

15. The method according to claim 6 wherein step 3) is performed by means of suction.

16. The method according to claim 8 wherein the two workpieces (3, 4) are moved during step 2).

Description

[0026] Shown is:

[0027] FIG. 1 is a schematic view of a first embodiment according to the invention.

[0028] FIG. 1 shows a first embodiment that implements the method according to the invention.

[0029] A sonotrode 1 and an counter-tool 2 are provided. The counter tool 2 is cylindrical in this case. The sonotrode 1 can be set into ultrasonic vibration. Two strips of material 3, 4 are intended to be welded together. Thus, they are guided on top of each other through the gap between the sonotrode 1 and the counter-tool 2. The feed rate of the strips of material corresponds to the circumferential speed of the anvil roll 2.

[0030] While the two strips of material 3, 4 are passing between the sonotrode 1 on the one hand and the counter-tool 2 on the other hand, a joining force is applied to the strips and an ultrasonic vibration is generated. To improve the adhesion between the strips of material, thermoplastic particles 5 are applied via the feeder 8 to a joining surface of the strip of material 4. The feed may be performed using an auger (not shown) and an air-to-air venturi nozzle 7.

[0031] The added thermoplastic particles 5 can rest loosely and on the strip of material 4 before the latter comes into contact with the strip of material 3. By means of the method according to the invention, the two strips of material 3, 4 are then present between the sonotrode 1 and the anvil 2, and individual thermoplastic particles 5 are present between the strips of material.

[0032] During ultrasonic processing, the thermoplastic particles 5 are melted so that they can penetrate into corresponding pores, fibre gaps, or previously introduced depressions in the strip of material 3, or in the strip of material 4. Once both strips of material have then completed processing by the sonotrode 1, a suction device 9 is provided that suctions excess thermoplastic particles 5.

[0033] Using the method according to the invention, natural fibres, e.g. cotton, can be connected to one another. For example, materials made of PP/PET fibres can already be effectively connected to one another.

LIST OF REFERENCE SIGNS

[0034] 1 Sonotrode [0035] 2 Counter-tool [0036] 3, 4 Strip of material [0037] 5 Thermoplastic particles 7 Venturi nozzle [0038] 8 Feed [0039] 9 Suction device