Workpiece having structural elements

Abstract

The invention relates to a processing element (1) for processing a material, such as a sonotrode (3) or anvil, having a substantially cylindrical or cylindrical segment shaped support surface (2) which is arranged for contacting the material during processing, the processing element (1) being arranged to rotate about its longitudinal axis (10) during processing, so that the support surface (2) moves in the circumferential direction and rolls on the material to be processed, and on the support surface (2) at least one structural element (4) is arranged, which extends radially beyond the support surface (2), the structural element (4) having a top surface which is arranged for contacting the material to be processed. In order to provide a processing element (1) which allows reliable welding at higher feed rates, according to the invention, the top surface has a base and at least one recess, which recess is at a smaller distance from the longitudinal axis (10) than the base, and in a cross section perpendicular to the longitudinal axis (10), the base and the recess are arranged side by side.

Description

[Technical Field]

[0001] The present invention relates to a processing element, such as a sonotrode or anvil, for ultrasonically processing materials. Such a processed member is described, for example, in Patent Document 1. [Background technology]

[0002] Ultrasonic waves are increasingly being used to bond nonwoven materials. Two nonwoven pieces to be bonded are inserted one above the other into the gap between a sonotrode and anvil, and ultrasonic vibrations are applied to the sonotrode. Spot heating occurs at the overlapping contact surfaces due to friction induced by the ultrasound, melting the thermoplastic components of the nonwovens. The molten components of the material pieces to be bonded flow into each other, resulting in a solid bond after cooling.

[0003] That is, suitable nonwoven sections can be bonded together when forming a diaper.

[0004] Gathering is often desirable when processing nonwoven fabrics. To achieve this, additional elastic threads are inserted between the nonwoven fabric sections to be bonded. The nonwoven fabric sections to be bonded are then bonded to one another at at least two bonding surfaces, with the threads being ultrasonically fixed between the two bonding surfaces during processing so that a positive bond exists between the threads and the nonwoven fabric sections in two spatial directions oriented perpendicular to one another. In this way, the material can be gathered.

[0005] The working member may have a substantially cylindrical or cylindrical segment shaped support surface that is provided for contacting the material during processing, and the working member rotates about its longitudinal axis during processing, so that the support surface rolls on the material to be processed.

[0006] The support surface often has at least one structural element which extends radially beyond the support surface, so that the structural element has an upper surface which is intended for contact with the material to be processed, the actual welding being carried out in the area between the upper surface of the structural element and the sealing surface of the counter element arranged at a distance therefrom.

[0007] When secured by threads, the elongated structural elements typically extend along the longitudinal axis of each component, and therefore the structural elements are usually oriented at an angle, at least perpendicular, to the orientation of the threads. Thus, the structural elements partially bond the threads to the nonwoven fabric. Regions where the threads are free to move alternate with regions where the threads are bonded to portions of the nonwoven fabric. This bond can be achieved by frictional bonding in a spatial direction where no geometric bond exists between the nonwoven fabric and the threads, or by material bonding. If the threads are stretched during ultrasonic processing, partially securing the threads can cause the nonwoven fabric to gather when the threads relax after processing.

[0008] For example, the counter element can be a sonotrode and the working element can be an anvil. In the following, the invention will be explained using this example, since this is the preferred embodiment. However, in principle, it is also possible to configure the working element as a sonotrode and the counter element as an anvil.

[0009] During processing, the support surface with the structural elements rolls on the material to be processed, so that the structural elements in particular bring about welding.

[0010] Processing speed is limited by prior art equipment.

[0011] In principle, the feed rate, i.e. the speed at which the material moves through the gap between the work member and the counter member, is increased.

[0012] Of course, in that case, a sonotrode acting on the material at a fixed frequency will no longer put enough energy into the material to allow a reliable weld, since at higher feed rates the material will be in contact with the sealing surface of the sonotrode for a shorter time, and therefore the sonotrode will cause less "impact" on the material.

[0013] This can be partially compensated for by increasing the force with which the sonotrode is pressed against the material to be processed. This transfers more energy into the material "per impact" of the sonotrode. Of course, this leads to higher friction, and the molten components formed by ultrasonic processing at the interface between the material parts to be welded, i.e., in the so-called joint zone, are pushed out of the joint zone by the structural elements, which also leads to deterioration of the seam, since there is no longer enough thermoplastic component in the joint zone. Alternatively, or in addition, the vibration frequency of the ultrasonic vibrations can be increased. This also transfers more energy into the material "per impact" of the sonotrode. However, this can only be done to a limited extent. If the sonotrode is driven with a higher vibration amplitude, damage to the sonotrode material may occur.

[0014] To achieve higher processing speeds, so-called "welding wheels" have already been used, in which several sonotrodes are arranged on one wheel in order to increase the contact time during the rotational movement of the wheel, but this solution is very complicated.

[0015] Furthermore, when attempting to bond a thread to a nonwoven fabric, an additional problem occurs when the structural element is too narrow, as the thread is not clamped tight enough because the clamping force is reduced due to the small interaction surface with the nonwoven fabric, which corresponds to the upper surface of the structural element. On the other hand, if a structural element with a width that is too wide is selected, the interaction surface and therefore the clamping force will increase, but of course, a larger interaction surface will also increase friction with the material to be processed. Furthermore, if the structural element is too wide, the free space in which the thread can move unhindered will be reduced, which will have a negative effect on the gathering properties of the material. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] European Patent No. 3209433(B1) Summary of the Invention [Problem to be solved by the invention]

[0017] Based on the above-mentioned prior art, it is therefore an object of the present invention to provide a workpiece that allows reliable welding. [Means for solving the problem]

[0018] According to the invention, this problem is solved by providing a device having an upper surface with a base and at least one recess, the recess being at a shorter distance from the longitudinal axis than the base, and the base and the recess being arranged side by side in a cross section perpendicular to the longitudinal axis. , the notch formed by the recess does not extend to the support surface. This is resolved by:

[0019] When the structural element rolls on the material, the plasticized component melts in the recesses, thereby reducing the extrusion of the plasticized component from the bonding zone mentioned above.

[0020] In the case of thread fixing, the concentration of the melt in the recesses additionally improves the clamping of the thread.

[0021] The recesses also reduce the effective interaction area and therefore the friction with the material. At the same time, the structural elements can be made wider, so that the threads are better secured. Furthermore, the recesses allow for less force to be applied between the processing element and the counter element to achieve the same processing result. Furthermore, an improvement in the feel of the resulting product has been observed.

[0022] In a preferred embodiment, the notch preferably has a depth of less than 1 mm, and best between 0.05 mm and 0.2 mm.

[0023] In a preferred embodiment, the notch formed by the recess does not extend to the surface of the substrate and preferably has a depth of less than 1 mm, and best between 0.05 mm and 0.2 mm.

[0024] In another preferred embodiment, the recesses are formed as grooves that are not aligned only in the circumferential direction. If the grooves are aligned in the circumferential direction, they preferably do not surround the entire support surface but extend over a circumferential angle of less than 360°, and particularly best over a circumferential angle of less than 45°, in particular less than 25°. It is also possible for several grooves to be spaced apart from one another in the circumferential direction.

[0025] The groove does not interrupt the weld, but simply receives the molten material so that the material remains substantially in place and in position and is available for joining the layers of material.

[0026] It has been shown that this groove can prevent the melt from undesirably shifting position on the material to be processed due to the pressure buildup of the sonotrode at the groove location, and the melt only moves up to the groove, which therefore serves as a reservoir for the molten material.

[0027] In a preferred embodiment, the groove has a width of less than 1 mm, preferably less than 0.6 mm. Best, the groove width is between 0.2 and 0.4 mm.

[0028] The groove is 0.15 mm according to the material to be welded. 2 It may be sufficient if the cross-sectional area is less than 0.05 mm. 2 Smaller, best is 0.015mm 2 and 0.04 mm 2 It is between.

[0029] In a preferred embodiment, the structural element has a plurality of grooves, preferably at least three, on its upper surface, which are not circumferentially oriented, and preferably are parallel to one another, so that the grooves can hold the molten material in place, and thus multiple grooves are effective.

[0030] In another preferred embodiment, the upper surface of the structural element has a main portion and at least one chamfer that is circumferentially continuous around the main portion, which is substantially flat or has a convex curvature with a radius of curvature corresponding to the distance of the main portion from the cylindrical axis. The chamfer is bent relative to the main portion so that the main portion and the chamfer form an angle of less than 180°, or the chamfer is convexly curved, and if the main portion is convexly curved, the radius of curvature of the chamfer is smaller than that of the main portion. Preferably, at least one recess is arranged in the main portion. The chamfer is used to gradually provide material to the welding contact between the main portion and the counter-element. At the transition between the main portion and the chamfer, the slope or curvature of the upper surface changes. This ensures that the distance between the structural element and the counter-element is continuously reduced when the workpiece is used, until a minimum distance is achieved between the structural element and the counter-element.

[0031] In another preferred embodiment, the upper surface has two chamfers that are circumferentially contiguous with the main part on opposite sides and are bent relative to the main part so that the main part and the chamfers each form an angle of less than 180°. Thus, when machining, the upper surface of the structural element not only has an incoming chamfer, but also an outgoing chamfer, so that even at the end of machining of the structural element, the forces exerted by the counter-part on the machining part are only gradually reduced.

[0032] In another preferred embodiment, the upper surface of the structural element has an elongated shape with a length l and a width b, where l>b. This length preferably does not extend parallel to the longitudinal axis, but best substantially perpendicular thereto.

[0033] In another embodiment, the structural element and the recesses disposed on the upper surface extend continuously over the entire length l of the workpiece, the length l being oriented substantially parallel to the longitudinal axis. Preferably, the length l of the structural element is much greater than the width b of the structural element, which is oriented substantially perpendicular to the length l.

[0034] In another embodiment, the structural element also extends substantially along the longitudinal axis of the workpiece, and the structural element and the recess disposed on the upper surface extend in a serpentine shape, with the base also extending in a similar serpentine shape.

[0035] The invention also relates to an ultrasonic welding device having a workpiece as just described, which in addition to the workpiece also has a counter-element, which has a sealing surface that can be arranged facing the workpiece, so that a gap is formed between the upper surface of the structural element of the workpiece and the sealing surface of the counter-element, into which the material to be processed can be placed, and in cross-section perpendicular to the longitudinal axis of the workpiece, the sealing surface has a weld that is at least partially concavely curved.

[0036] As already noted above, the counter element can be the sonotrode and the processing element can be the anvil. By partially curving the weld, the contact time between the sonotrode and the anvil is extended, so that more energy can be injected into the material, which in turn allows for a higher feed rate without having to increase the force with which the sonotrode is pressed against the material to be processed.

[0037] In another preferred embodiment, the radius of curvature of the concavely curved portion of the counter element corresponds approximately to the radius of curvature of the main portion of the workpiece. In practice, it is particularly advantageous if the radius of curvature of the concavely curved portion of the counter element is slightly larger than the radius of curvature of the main portion of the workpiece. The difference between the two radii of curvature corresponds to the width of the gap remaining between the sealing surface and the upper surface of the structural element during the welding process.

[0038] In another embodiment, the counter-element has a groove for at least partially accommodating at least one thread, the groove being oriented in the feed direction, and the material to be processed in the groove is moved through the gap between the processing element and the counter-element, the material to be processed consisting of at least two material fabric parts and at least one thread, the at least one thread being positioned between the two material fabric parts. In this way, pleated materials can also be formed in an ultrasonic welding device by the processing element according to the invention.

[0039] In another preferred embodiment, the sealing surface has an inlet located next to the weld and which is not curved or is concavely curved with a radius of curvature greater than that of the weld. Again, at the transition between the inlet and the weld, the slope or curvature of the sealing surface changes, so that the distance between the workpiece and the counter-element in the area of ​​the inlet gradually decreases until a minimum distance is reached, which corresponds to the distance between the weld and the upper surface of the structural element. The inlet is arranged so that the material being moved through the gap in the feed direction first comes into contact with the inlet and then with the weld.

[0040] Advantageously, the penetration and weld are of approximately equal size.

[0041] Other advantages, features and applicability of the present invention will become apparent from the following description of preferred embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 shows an ultrasonic welding device in perspective view. [Figure 2] FIG. 2 shows an enlarged detail of the area indicated by X in FIG. [Figure 3] FIG. 3 shows an enlarged detail of FIG. [Figure 4] FIG. 4 shows the ultrasonic welding apparatus of FIG. 1 in a side view. [Figure 5] FIG. 5 shows an enlarged view of a portion of FIG. [Figure 6] FIG. 6 shows a schematic diagram of another embodiment of the workpiece according to the present invention. [Figure 7] FIG. 7 shows an enlarged view of the schematic representation in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0043] Figure 1 shows a perspective view of an ultrasonic welding device. The ultrasonic welding device has a workpiece 1 configured as an anvil, which is here configured as a roller that can rotate about a longitudinal axis 10. At least one transverse seam strip 11 having a support surface 2 is arranged on the roller. Opposite it is a counter element 3 configured as a sonotrode.

[0044] The counter element 3 can here be excited by ultrasonic vibrations. The material to be processed is moved between the support surface 2 and the sealing surface of the sonotrode 3 facing towards the support surface 2, the processing speed of the material corresponding to the peripheral speed of the processing element 1. The gap between the support surface 2 and the sonotrode 3 is selected so that, during processing, the ultrasonic vibrations are transmitted to the material and melting of the thermoplastic component occurs at the interface.

[0045] FIG. 2 shows an enlarged detail of FIG.

[0046] It can be seen that a number of structural elements 4 are disposed on the support surface 2. These structural elements 4 have an elongated shape and are circumferentially oriented. The structural elements 4 contact the material during processing and define a weld pattern that is formed in the material during processing. Ultrasonic welding equipment can be used, for example, to form side seams in nonwoven diapers.

[0047] Figure 3 shows an enlarged view of the detail in Figure 2, in which the structural elements 4 can be clearly seen. In the circumferential direction (relative to the longitudinal axis 10), two structural elements 4 are arranged side by side. In the axial direction, a large number of pairs of such structural elements are arranged side by side.

[0048] Each structural element has a main portion 6 and two chamfers 7, 8, which are significantly curved compared to the main portion 6. Grooves 5 are formed in the main portion 6, which in the illustrated embodiment extend perpendicular to the circumferential direction. It is not necessary for the grooves to extend perpendicular to the circumferential direction. However, to achieve the inventive effect, the grooves are not arranged parallel to the circumferential direction. However, if the grooves are arranged parallel to the circumferential direction, they would not extend over the entire structural element 4.

[0049] When welding, the structural element 4 rolls on the material to be worked, so that the chamfer 8 first comes into contact with the material to be worked. Due to the rounded arrangement of the chamfer 8, the distance between the structural element 4 and the opposing sealing surface of the counter element 3 in this area gradually decreases until a minimum distance is reached in the area of ​​the main part 6. The main part 6 can be formed convexly curved, the radius of curvature corresponding approximately to the distance between the upper surface of the structural element 4 and the longitudinal axis 10 of the workpiece 1.

[0050] In the main part 6, the grooves 5 are formed with a depth of 0.1 mm and a width of 0.3 mm, creating cutouts into which the molten material can penetrate, so that it remains substantially in place and in position and is not pushed out of the joining zone by the structural element.

[0051] Figure 4 shows a side view of the ultrasonic welding installation of Figure 1. Surface 9 is the sealing surface, i.e. the surface facing the support surface or structural element 4.

[0052] FIG. 5 shows an enlarged portion of FIG. 4. The surface 9 here consists of an entry section 9a and a weld section 9b. The weld section 9b is curved concavely, in particular with a radius of curvature substantially equal to the radius of curvature of the main section of the workpiece. This measure ensures that the material remains in contact with the sonotrode longer during processing, allowing more energy to be injected into the material to be processed. In this embodiment, the entry section 9a is not curved, which ensures that the material to be processed is guided into a gap that first narrows in the area of ​​the entry section 9a. The gap then becomes minimal in the area of ​​the weld section 9b and remains substantially constant in the area of ​​the weld. The welding is primarily performed by the weld section 9b, but the entry section 9a can already contribute to the welding at its end facing the weld section 9b.

[0053] 6 and 7 show an alternative embodiment of the processing element 1 according to the invention, which is particularly suitable for forming pleated material. To this end, at least one thread is threaded between two material sections of the material to be processed and is connected to the material sections by means of a structural element 4, partly by force or material bonding. The structural element 4 extends continuously over the entire extent of the anvil 1 in the direction of the longitudinal axis 10. Furthermore, the structural element 4, and thus the groove 5, also extends in a meandering line (see FIG. 7). The embodiment shown in FIGS. 6 and 7 ensures a stable connection of the thread with the material sections and simultaneously reduces friction between the processing element 1 and the material. The present invention has the following aspects (configurations). [Aspect 1] a processing element for processing a material, such as a sonotrode or anvil, A processing element having a support surface of substantially cylindrical or cylindrical segment shape, the support surface being adapted to contact the material during processing, the processing element being adapted to rotate about a longitudinal axis during processing, the support surface moving in a circumferential direction and rolling on the material to be processed, at least one structural element being arranged on the support surface, the structural element extending radially beyond the support surface, the structural element having an upper surface adapted to contact the material to be processed, the upper surface having a base and at least one recess, the recess having a shorter distance from the longitudinal axis than the base, the base and the recess being juxtaposed to one another perpendicular to the longitudinal axis in a cross-sectional view. [Aspect 2] 2. The processed member according to claim 1, wherein the notch formed by the recess does not extend to the support surface, and preferably the notch has a depth of less than 1 mm, and particularly preferably between 0.05 mm and 0.2 mm. [Aspect 3] 3. The workpiece of claim 1 or 2, wherein the recesses are formed as grooves, the grooves preferably not oriented in the circumferential direction. [Aspect 4] 4. The workpiece according to claim 3, wherein the width of the groove is less than 1 mm, preferably less than 0.6 mm, and particularly preferably between 0.2 and 0.4 mm. [Aspect 5] 5. The workpiece according to claim 3 or 4, wherein the groove has a cross-sectional area of ​​less than 0.15 mm, preferably less than 0.05 mm, and particularly preferably between 0.015 mm and 0.04 mm. [Aspect 6] 6. The processed member of any one of aspects 3 to 5, wherein the structural element has a number of grooves, preferably at least three grooves, that are not circumferentially oriented on the upper surface, and the grooves are preferably arranged parallel to one another. [Aspect 7] 7. The workpiece of any one of Aspects 1 to 6, wherein the upper surface has a main portion that is generally flat or has a convex curve with a radius of curvature corresponding to the distance of the main portion from a cylindrical axis, and at least one chamfer that is circumferentially continuous with the main portion, the chamfer being angled relative to the main portion such that the main portion and the chamfer form an angle of less than 180°, and / or is convexly curved, such that when the main portion is convexly curved, the radius of curvature of the chamfer is smaller than the radius of curvature of the main portion, and preferably the at least one recess is located within the main portion. [Aspect 8] A processed member according to any one of aspects 1 to 7, comprising at least two structural elements spaced apart from each other in the circumferential direction. [Aspect 9] 9. The processed member according to any one of aspects 1 to 8, wherein the processed member is formed as an anvil. [Aspect 10] 10. The processed member according to any one of aspects 1 to 9, wherein the upper surface has an elongated shape with a length l and a width b, where l>b. [Aspect 11] 11. The workpiece according to any one of aspects 1 to 10, wherein the structural element (4) and the recess (5) arranged on the upper surface extend continuously over the entire length l of the workpiece, the length l being oriented substantially parallel to the longitudinal axis (10). [Aspect 12] An ultrasonic welding device having the processed member and a counter member according to any one of aspects 1 to 11, an ultrasonic welding device, wherein the counter member has a sealing surface, the sealing surface can be positioned opposite the workpiece, a gap is formed between the upper surface and the sealing surface, and a material to be processed can be placed in the gap, and when viewed in a cross section perpendicular to the longitudinal axis of the workpiece, the sealing surface has a weld portion, and the weld portion is at least partially concavely curved. [Aspect 13] 13. The ultrasonic welding device according to claim 12, wherein the radius of curvature of the concavely curved portion of the counter member substantially corresponds to the radius of curvature of the main portion of the workpiece. [Aspect 14] 14. The ultrasonic welding apparatus of claim 12 or 13, wherein the counter member has a groove for at least partially accommodating at least one thread, the groove being oriented in the feed direction, within which the material to be processed moves through a gap between the processing member and the counter member, the material to be processed comprising at least two material woven portions and at least one thread, and the at least one thread being positioned between the two material woven portions. [Aspect 15] 14. The ultrasonic welding apparatus of claim 12 or 13, wherein the sealing surface has an entry portion, the entry portion is located adjacent the weld portion, and the entry portion is either uncurved or concavely curved with a radius of curvature greater than the radius of curvature of the weld portion. [Aspect 16] 15. The ultrasonic welding device of claim 14, wherein the processing member is configured to rotate in a feed direction, the material to be processed moves between the processing member and the counter member in the feed direction, and the entry portion and the welding portion are arranged as follows: the material moving through the gap in the feed direction first comes into contact with the entry portion and then with the welding portion. [Aspect 17] 16. The ultrasonic welding device of claim 14, wherein the entry portion and the welding portion are approximately the same size. [Aspect 18] 17. The ultrasonic welding device according to any one of aspects 12 to 16, wherein the counter member is formed as a sonotrode. [Explanation of symbols]

[0054] 1. Processing material (anvil) 2 Support surface 3 Counter element (sonotrode) 4 Structural Elements 5 grooves 6 Main parts 7, 8 Chamfered parts 9 Sealing surface 9a Entrance section 9b Welded section 10 Longitudinal axis 11 Horizontal seam strip

Claims

1. A processing element (1) for processing a material, such as a sonotrode or anvil, A processing element (1) having a support surface (2) of substantially cylindrical or cylindrical segment shape, said support surface (2) being arranged to come into contact with the material during processing, said processing element (1) being arranged to rotate about a longitudinal axis (10) during processing, said support surface (2) moving in a circumferential direction and rolling on the material to be processed, at least one structural element (4) being arranged on said support surface (2), said structural element (4) extending radially beyond said support surface (2), said structural element (4) having an upper surface arranged to come into contact with the material to be processed, The workpiece (1) is characterized in that the upper surface has a base and at least one recess (5), the recess (5) being at a shorter distance from the longitudinal axis (10) than the base, the base and the recess (5) being juxtaposed to each other perpendicular to the longitudinal axis (10) in a cross-sectional view, and the cutout formed by the recess (5) not extending to the support surface (2).

2. 2. Workpiece (1) according to claim 1, characterized in that the notch has a depth of less than 1 mm, particularly preferably between 0.05 mm and 0.2 mm.

3. 3. Workpiece (1) according to claim 1 or 2, characterized in that the recesses are formed as grooves (5), which grooves (5) are preferably not oriented in the circumferential direction.

4. 4. Workpiece (1) according to claim 3, characterized in that the width of the groove (5) is less than 1 mm, preferably less than 0.6 mm, and particularly preferably between 0.2 mm and 0.4 mm.

5. The groove (5) is 0.15 mm ２ smaller than 0.05 mm ２ and particularly preferably has a cross-sectional area smaller than 0.015 mm ２ and 0.04 mm ２ 5. The workpiece (1) according to claim 3 or 4, characterized in that:

6. 6. The workpiece (1) according to any one of claims 3 to 5, characterized in that the structural element (4) has, on the upper surface, a number of grooves (5) not oriented in the circumferential direction, preferably at least three grooves (5), preferably arranged parallel to one another.

7. 7. The workpiece (1) according to claim 1, wherein the upper surface comprises a main portion (6) that is substantially flat or has a convex curve with a radius of curvature corresponding to the distance of the main portion (6) from the cylindrical axis, and at least one chamfer (7, 8) that is circumferentially continuous with the main portion (6), the chamfer (7, 8) being angled relative to the main portion (6) so that the main portion (6) and the chamfer (7, 8) form an angle of less than 180° and / or the top surface is convexly curved, the radius of curvature of the chamfer (7, 8) being smaller than the radius of curvature of the main portion (6) when the main portion (6) is convexly curved, and preferably the at least one recess (5) is arranged in the main portion (6).

8. Workpiece (1) according to any one of the preceding claims, characterized in that at least two structural elements (4) are provided, spaced apart from one another in the circumferential direction.

9. 9. The processing element (1) according to any one of the preceding claims, characterized in that the processing element (1) is formed as an anvil.

10. Workpiece (1) according to any one of the preceding claims, characterized in that the upper surface has an elongated shape with a length l and a width b, where l>b.

11. 11. The workpiece (1) according to claim 1, wherein the structural element (4) and the recess (5) arranged on the upper surface extend continuously over the entire length l of the workpiece (1), the length l being oriented substantially parallel to the longitudinal axis (10).

12. An ultrasonic welding device having a workpiece (1) according to any one of claims 1 to 11 and a counter element (3), The counter member (3) has a sealing surface (9) that can be arranged facing the workpiece (1), a gap is formed between the upper surface and the sealing surface (9) and a material to be processed can be placed in the gap, and when viewed in a cross section perpendicular to the longitudinal axis (10) of the workpiece (1), the sealing surface (9) has a weld portion (9b) that is at least partially concavely curved.

13. 13. An ultrasonic welding device according to claim 12, characterized in that the radius of curvature of the concavely curved portion of the counter-piece (3) corresponds approximately to the radius of curvature of the main portion (6) of the workpiece (1).

14. 14. The ultrasonic welding device according to claim 12 or 13, wherein the counter-element (3) has a groove for at least partially accommodating at least one thread, the groove being oriented in the feed direction, in which the material to be processed is moved through a gap between the processing element (1) and the counter-element (3), the material to be processed consisting of at least two material woven parts and at least one thread, the at least one thread being positioned between the two material woven parts.

15. 14. An ultrasonic welding device according to claim 12 or 13, characterized in that the sealing surface (9) has an inlet (9a), which is arranged next to the weld (9b) and is not curved or is concavely curved with a radius of curvature larger than the radius of curvature of the weld (9b).

16. 15. The ultrasonic welding device according to claim 14, characterized in that the processing element (1) is arranged to rotate in a feed direction, in which the material to be processed moves between the processing element (1) and the counter element (3), and the entry portion (9a) and the welding portion (9b) are arranged as follows: the material moving through the gap in the feed direction first comes into contact with the entry portion (9a) and then with the welding portion (9b).

17. 17. An ultrasonic welding device according to claim 15 or 16, characterized in that the entry portion (9a) and the welding portion (9b) are of approximately the same size.

18. 17. Ultrasonic welding device according to any one of claims 12 to 16, characterized in that the counter element (3) is formed as a sonotrode.

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