DEVICE AND METHOD FOR PRODUCING A GATHERED MATERIAL

Abstract

An apparatus for producing a gatherable material, wherein the material consists of at least two material web sections and one thread positioned between the material web sections, wherein the apparatus has a tool with a sealing surface and a counter-tool with a counter-sealing surface, wherein the tool and the counter-tool are arranged relative to one another such that the material web sections and the thread are guided through a gap formed by the tool and counter-tool, wherein the tool and/or the counter-tool has a groove for receiving the thread, wherein the groove is orientated in a feed direction divides the sealing or counter-sealing surface into partial sealing surfaces, and has a groove base and two side walls, wherein the side walls connect the groove base to the partial sealing surfaces, and at least one of the partial sealing surfaces has a flank which slopes down towards the groove base.

Claims

1. A device for producing a gathered or gatherable material, the material consisting of at least two material web sections and at least one thread positioned between the material web sections, the device comprising: a tool with a sealing surface and a counter-tool with a counter-sealing surface, the tool and the counter-tool being arranged relative to one another in a processing position in such a way that for producing the gathered or gatherable material in an operation of the device, the material web sections and the thread are guided through a gap formed by the sealing surface and the counter-sealing surface in a feed direction, wherein the tool and/or the counter-tool has at least one groove for at least partially receiving the at least one thread, wherein the groove is orientated in the feed direction, wherein the groove divides the sealing surface and the counter-sealing surface, respectively, into partial sealing surfaces, wherein the groove has a groove base and two side walls adjoining the groove base, wherein the side walls connect the groove base to the partial sealing surfaces, and wherein at least one of the partial sealing surfaces has, in a sectional view perpendicular to the feed direction, at least one flank sloping down towards the groove base.

2. The device according to claim 1, wherein each of the partial sealing surfaces in a sectional view perpendicular to the feed direction has one or two flanks sloping down towards the groove base.

3. The device according to claim 2, wherein the one or two flanks is/are convexly curved in a sectional view perpendicular to the feed direction with a radius R.sub.F, the radius R.sub.F preferably being between 0.01 mm and 0.5 mm and particularly preferably between 0.05 mm and 0.2 mm.

4. The device according to claim 1, wherein the groove base is concavely curved, the concavely curved groove base preferably directly adjoining the preferably convexly curved flank of the partial sealing surface.

5. The device according to claim 3, wherein the groove base is concavely curved with a radius R.sub.G in a sectional view perpendicular to the feed direction, wherein preferably 5R.sub.F>R.sub.G>0.5R.sub.F and particularly preferably 2.5R.sub.F>R.sub.G>0.8R.sub.F.

6. The device according to claim 1, wherein the at least one groove is arranged on the sealing surface of the tool.

7. The device according to claim 1, wherein the counter-tool is cylindrical and rotatable about a first cylindrical axis, wherein the counter-tool has a lateral surface on which the counter sealing surface is arranged, wherein the first cylindrical axis is orientated such that the feed direction is tangential to the lateral surface.

8. The device according to claim 1, wherein the sealing surface is substantially flat.

9. The device according to claim 1, wherein the groove extends completely over an extension of the sealing surface of the tool and/or of the counter-sealing surface in the feed direction.

10. The device according to claim 1, wherein the tool is cylindrical, wherein the tool is rotatable about a second cylindrical axis and has a lateral surface on which the sealing surface is arranged, wherein preferably the at least one groove runs in a circle around the lateral surface of the tool.

11. The device according to claim 1, wherein the sealing surface and/or the counter-sealing surface has a plurality of grooves orientated in the feed direction for at least partially receiving the at least one thread, wherein preferably the grooves have a spacing between 0.1 and 10 mm and particularly preferably between 0.4 and 2.5 mm.

12. The device according to claim 11, wherein a plurality of grooves are combined in groove packets, wherein the grooves of a groove packet preferably have a spacing between 0.1 and 10 mm, wherein the groove packets preferably have a spacing between 5 and 300 mm from one another.

13. The device according to claim 1, wherein the at least one groove has a depth of between 0.05 mm and 0.8 mm.

14. The device according to ene of the preceding claims, claim 1, wherein the partial sealing surfaces are convexly curved in a sectional view perpendicular to the feed direction with a radius of curvature R.sub.T, wherein preferably R.sub.F=R.sub.T.

15. The device according to claim 1, wherein the tool is a sonotrode of an ultrasonic processing device or a tool which is thermally heated.

16. The device according to claim 1, wherein the one or two flanks adjoin/adjoins one of the side walls, wherein the one or two flanks make/makes a first angle with the partial sealing surface which is different from a second angle which the side wall makes with the partial sealing surface.

17. A method of producing a gathered or gatherable material, the method comprising the following steps: a. providing at least two material web sections and at least one thread, which is arranged between the material web sections, b. providing a device according to claim 1, c. passing the at least two material web sections and the at least one thread through the gap between the sealing surface of the tool and the counter-sealing surface in the feed direction, the thread being guided through the at least one groove of the sealing surface and/or of the counter-tool while the tool is activated, so that the two material web sections are welded together at at least two connecting surfaces, the thread being arranged between the two connecting surfaces in such a way that there is a positive connection between the thread and the material web sections in a first and a second direction, the two directions being aligned perpendicular to one another.

18. The method according to claim 17, wherein a cross-section of the thread during processing is selected such that during step c. not only the two material web sections are welded together, but also an outer section of the thread is welded to the material web sections, so that the thread is clamped between the two material web sections.

19. The device according to claim 2, wherein the sealing surface and/or the counter-sealing surface has a plurality of grooves orientated in the feed direction for at least partially receiving the at least one thread, wherein the one or two flanks adjoin/adjoins one of the side walls, wherein the one or two flanks make/makes a first angle with the partial sealing surface which is different from a second angle which the side wall makes with the partial sealing surface.

20. The device according to claim 2, wherein the sealing surface and/or the counter-sealing surface has a plurality of grooves orientated in the feed direction for at least partially receiving the at least one thread, wherein preferably the grooves have a spacing between 0.1 and 10 mm and particularly preferably between 0.4 and 2.5 mm, wherein the partial sealing surfaces are convexly curved in a sectional view perpendicular to the feed direction with a radius of curvature R.sub.T, wherein preferably R.sub.F=R.sub.T.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Further advantages, features and possible applications will become apparent from the following description of an embodiment and the associated figures.

[0049] FIG. 1 shows a sectional view of a part of an embodiment of the device according to the invention.

[0050] FIG. 2a schematically shows the arrangement of the thread between the material webs after welding using methods known from the prior art.

[0051] FIG. 2b schematically shows the arrangement of the thread according to an embodiment of the method according to the invention.

[0052] FIG. 3 shows a schematic overall view of an embodiment of the device according to the invention.

[0053] FIG. 4a shows a schematic representation of a longitudinal section of an embodiment of the material according to the invention in the ungathered state.

[0054] FIG. 4b shows a schematic representation of a longitudinal section of an embodiment of the material according to the invention in the gathered state.

[0055] FIG. 4c shows a schematic representation of a three-dimensional view of an embodiment of the material according to the invention.

[0056] FIG. 3 shows an embodiment of the device according to the invention, which has a sonotrode 1 with a sonotrode sealing surface 2 and a counter tool 14, which is cylindrical in shape and lies opposite the sonotrode sealing surface 2 of the sonotrode 1. The sonotrode 1 and the counter tool 14 form a gap in which the material web sections 11, 12 and the thread 13 are guided in a feed direction.

[0057] According to the embodiment of the device according to the invention shown in FIG. 1, the grooves 3 for receiving the thread 13 are arranged in the sonotrode sealing surface 2 of a sonotrode 1. The grooves 3 run in the feed direction, which extends into the sheet plane in the sectional view shown in FIG. 1. In addition, the grooves 3 divide the sonotrode sealing surface 2 into several partial sealing surfaces 7.

[0058] The grooves 3 have a groove base 4 and two side walls 5, 6 adjoining the groove base, whereby the side walls 5, 6 connect the groove base 4 with the partial sealing surfaces 7.

[0059] In the sectional view shown in FIG. 1, the partial sealing surfaces 7 each have two flanks 8 sloping down towards the groove base 4 perpendicular to the feed direction.

[0060] The sloping flanks 8 are convexly curved with a radius R.sub.F, so that the entire partial sealing surface 7 is convexly curved with a radius R.sub.T=R.sub.F. Furthermore, the groove base 4 is also concavely curved with a radius R.sub.G and directly adjoins the convexly curved flanks of the partial sealing surfaces 7. The radius R.sub.T of the curved partial sealing surface 7 corresponds to the radius R.sub.G of the concavely curved groove base 4 and is 0.1 mm.

[0061] The grooves also have a width B of 0.22 mm, whereby the width is measured between the two transition points of the concavely curved groove base 4 and the convexly curved flank 8.

[0062] In addition, the grooves 3 have a depth T of 0.21 mm. The depth T of the grooves 3 is defined between the deepest point of the groove base 4 and the highest point of the partial sealing surface 7. The distance A between two grooves is 0.42 mm, whereby the distance A is measured at the deepest point of the groove base 4.

[0063] To produce a gatherable or gathered material 10, two material webs 11, 12 are arranged between the sonotrode sealing surface 2 of the sonotrode 1 and the counter-sealing surface of a counter tool (not shown), between which a thread 13 is arranged. The thread 13 is guided in such a way that it runs inside the grooves 3. Ultrasonic processing of the material web sections 11, 12 only occurs in the area of the partial sealing surfaces 7.

[0064] In methods known from the prior art and also in an embodiment of the method according to the invention, a diameter of the thread 13 in a state in which the thread is tensioned is selected such that it is smaller than a depth of the groove 3. This means that the thread 13 is not processed by the sonotrode 1.

[0065] The result of such a process with devices known from the prior art, i.e. with devices whose grooves have sharp edges, is shown in FIGS. 2a and 4c. The thread 13 is clamped in a cavity between the material web sections 11, 12 of the material 10, but can move in the feed direction relative to the material web sections 11, 12. The lower material web section 12 has the shape of the grooves, which can be arranged on the sonotrode or the counter tool or on both.

[0066] In another embodiment of the method according to the invention, the cross-section of the thread 13 is selected so that it is greater than a depth of the groove 3. The result of the method according to the invention is shown in FIG. 2b. By selecting the larger cross-section of the thread 13, the thread 13 is welded in the area of the partial sealing surface 7. As a result, the thread 13 is also attached to the material web sections 11, 12 and can no longer be moved in the feed direction.

[0067] In this way, a gathered or gatherable material can be produced, as shown in FIGS. 4a to 4c, whose threads are always arranged in the same position. FIG. 4a shows a longitudinal section along the feed direction, in which the thread 13 is stretched, i.e. the material web sections 11, 12 are not gathered, while FIG. 4b shows the unstretched state of the thread 13, in which the material web sections 11, 12 are gathered in the feed direction.

LIST OF REFERENCE SYMBOLS

[0068] 1 sonotrode [0069] 2 sonotrode sealing surface [0070] 3 groove [0071] 4 groove ground [0072] 5, 6 side walls [0073] 7 partial sealing area [0074] 8 flank [0075] 10 gathered or gatherable material [0076] 11, 12 material web sections [0077] 13 thread [0078] 14 counter-tool