PROCESSING ELEMENT COMPRISING A STRUCTURAL ELEMENT

Abstract

The present invention relates to a processing element for processing a material, such as, e.g. a sonotrode or an anvil, having a substantially cylindrical or cylinder-segment-shaped carrier surface which is intended to come into contact with the material during processing, the processing element being provided to be rotated about its longitudinal axis during processing, so that the carrier surface moves in a circumferential direction and rolls on the material to be processed, wherein at least one structural element is arranged on the carrier surface, which structural element protrudes in a radial direction beyond the carrier surface, wherein the structural element has a top surface which is intended to come into contact with the material to be processed. In order to provide a processing element enabling reliable welding at a higher feed rate, it is proposed according to the invention that the top surface comprises a base section and at least one recess section having a smaller distance from the longitudinal axis than the base section, wherein in a sectional view perpendicularly to the longitudinal axis, the base section and the recess section are arranged next to one another.

Claims

1. A processing element (1) for processing a material, such as a sonotrode or an anvil, comprising a substantially cylindrical or cylinder-segment-shaped carrier surface (2) which is intended to come into contact with the material during processing, the processing element (1) being intended to be rotated about its longitudinal axis during processing so that the carrier surface (2) moves in a circumferential direction and rolls on the material to be processed, at least one structural element (4) being arranged on the carrier surface (2), projecting in a radial direction above the carrier surface (2), the structural element (4) having an upper side intended to come into contact with the material to be processed, characterized in that the upper side has a base section and at least one recess section (5) which is at a smaller distance from the longitudinal axis (10) than the base section, wherein in a sectional view perpendicular to the longitudinal axis (10) the base section and recess section (5) are arranged next to one another, wherein the recess formed by the recess section (5) does not extend as far as the carrier surface (2).

2. The processing element (1) according to claim 1, characterised in that the recess has a depth of less than 1 mm.

3. The processing element (1) according to claim 1, characterised in that the recess section is formed as a groove (5).

4. The processing element (1) according to claim 3, characterised in that the groove (5) has a width which is smaller than 1 mm.

5. The processing element (1) according to claim 3, characterized in that the groove (5) has a cross-sectional area of less than 0.15 mm.sup.2.

6. The processing element (1) according to claim 3, characterised in that the structural element (4) has a plurality of grooves (5) in the top surface which are not circumferentially aligned.

7. The processing element (1) according to claim 1, characterized in that the top surface comprises a main section (6) which is formed substantially flat or with a convex curvature with a radius of curvature corresponding to the distance of the main section (6) from the cylinder axis, and at least one chamfer section (7,8) adjoining the main section in the circumferential direction, which chamfer section (7,8) is either angled with respect to the main section (6) so that the main section and the chamfer section (6, 7, 8) form an angle <180, and/or is convexly curved, wherein, if the main section (6) is convexly curved, the radius of curvature of the chamfer section (7,8) is smaller than the radius of curvature of the main section (6).

8. The processing element (1) according to claim 1, characterised in that at least two structural elements spaced apart from one another in the circumferential direction are provided.

9. The processing element (1) according to claim 1, characterised in that the processing element (1) is designed as an anvil.

10. The processing element (1) according to claim 1, characterised in that the top surface has an elongate shape with a length l and a width b, where l>b.

11. The processing element (1) according to claim 1, wherein the structural element (4) as well as the recess section (5) arranged on the top surface extend continuously over an overall length l of the processing element (1), wherein the length l is substantially oriented parallel to the longitudinal axis (10).

12. An ultrasonic welding apparatus comprising a processing element (1) according to claim 1 and a counter-element, the counter-element (3) having a sealing surface (9) which can be arranged opposite the processing element (1) so that a gap is formed between the top surface and the sealing surface (9) in which a material to be processed can be arranged, wherein, in a sectional view perpendicular to the longitudinal axis of the processing element (1), the sealing surface (9) has a welding section (9b) which is concavely curved at least in sections, characterized in that the welding section (9b) is formed by a welding material.

13. The ultrasonic welding apparatus according to claim 12, characterised in that the radius of curvature of the concavely curved section of the counter-element (3) corresponds approximately to the radius of curvature of the main section (6) of the processing element (1).

14. The ultrasonic welding apparatus according to claim 12, wherein the counter-element (3) comprises grooves for at least partially receiving at least one thread, which grooves are oriented in a feed direction in which the material to be processed is moved through the gap between the processing element (1) and the counter-element (3), wherein the material to be processed consists of at least two material web sections and the at least one thread, wherein the at least one thread is positioned between the two material web sections.

15. The ultrasonic welding apparatus according to claim 12, characterised in that the sealing surface (9) has an inlet section (9a) which is located adjacent to the welding section (9b) and is either non-curved or concavely curved with a radius of curvature which is larger than the radius of curvature of the welding section (9b).

16. The ultrasonic welding apparatus according to claim 14, characterised in that the processing element (1) is intended to be rotated in a feed direction in which a material to be processed is passed between the processing element (1) and the counter-element (3), wherein an inlet section (9a) and a welding section (9b) are arranged such that a material moved in the feed direction through the gap comes into contact first with the inlet section (9a) and then with the welding section (9b).

17. The ultrasonic welding apparatus according to claim 14, characterized in that the inlet section (9a) and the welding section (9b) are approximately equal in size.

18. The ultrasonic welding apparatus according to claim 12, characterised in that the counter-element (3) is designed as a sonotrode.

Description

[0039] Further advantages, features and possible applications of the present invention will become apparent from the following description of a preferred embodiment and the accompanying figures.

[0040] FIG. 1 shows a perspective view of an ultrasonic welding apparatus,

[0041] FIG. 2 shows a detailed enlargement of the section marked X in FIG. 1,

[0042] FIG. 3 shows a detailed enlargement of FIG. 2,

[0043] FIG. 4 shows a side view of the ultrasonic welding apparatus of FIG. 1,

[0044] FIG. 5 shows an enlarged partial view of FIG. 4,

[0045] FIG. 6 shows a schematic representation of a further embodiment of the processing element according to the invention, and

[0046] FIG. 7 shows an enlargement of the schematic representation in FIG. 6.

[0047] FIG. 1 shows a perspective view of an ultrasonic welding apparatus. The ultrasonic welding apparatus has a processing element 1 in the form of an anvil, which is designed here as a roller that can be rotated about a longitudinal axis 10. At least one transverse seam bar 11 with a carrier surface 2 is arranged on the roller. A counter-element 3 in the form of a sonotrode is arranged opposite.

[0048] The counter-element 3 can be excited here with an ultrasonic vibration. Material to be processed is then moved through between the carrier surface 2 and the sealing surface of the sonotrode 3 facing the carrier surface 2, whereby the speed of movement of the material corresponds to the peripheral speed of the processing element 1. The gap between the carrier surface 2 and the sonotrode 3 must be selected so that the ultrasonic vibration is transmitted to the material during processing and the thermoplastic components melt at the interfaces.

[0049] FIG. 2 shows a detailed enlargement of FIG. 1.

[0050] It can be seen that a plurality of structural elements 4 are arranged on the carrier surface 2. The structural elements 4 have an elongated shape, which are oriented in the circumferential direction. The structural elements 4 come into contact with the material during processing and determine the welding pattern that is introduced into the material during processing. The ultrasonic welding apparatus can be used, for example, to create side seams of nappies made of non-woven material.

[0051] FIG. 3 shows a detailed enlargement of FIG. 2, in which the structural elements 4 are clearly visible. In the circumferential direction (in relation to the longitudinal axis 10), two structural elements 4 are arranged next to each other. In the axial direction, a number of such pairs of structural elements are arranged next to each other.

[0052] Each structural element has a main section 6 and two chamfer sections 7, 8 which are more curved than the main section 6. Grooves 5 have been introduced in the main section 6, which in the embodiment shown run perpendicular to the circumferential direction. It is not necessary that the grooves run perpendicular to the circumferential direction. However, in order to achieve the effect according to the invention, they should not be arranged parallel to the circumferential direction. If the grooves are arranged parallel to the circumferential direction, they should not extend over the entire structural element 4.

[0053] During welding, the structural elements 4 roll on the material to be processed so that the chamfer section 8 first comes into contact with the material to be processed. Due to the angled arrangement of the chamfer section 8, the distance between the structural element 4 and the opposite sealing surface of the counter-element 3 successively decreases in this area until the smallest distance is reached in the area of the main section 6. The main section 6 can be convexly curved, whereby the radius of curvature essentially corresponds to the distance between the top surface of the structural element 4 and the longitudinal axis 10 of the processing element 1.

[0054] Grooves 5 with a depth of 0.1 mm and a width of 0.3 mm have been introduced in the main section 6. Molten material can penetrate into the resulting recesses so that it essentially remains in place and is not squeezed out of the joining zone by the structural elements.

[0055] FIG. 4 shows a side view of the ultrasonic welding apparatus of FIG. 1. The sealing surface, i.e. the surface facing the carrier surface or the structural elements 4, is surface 9.

[0056] FIG. 5 shows an enlarged partial view of FIG. 4. The surface 9 here consists of an inlet section 9a and a welding section 9b. The welding section 9b is concavely curved with essentially the same radius of curvature as the radius of curvature of the main section of the processing element. This measure ensures that during processing the material remains in contact with the sonotrode for longer, so that more energy can be introduced into the material to be processed. In this embodiment, the inlet section 9a is not curved and thus ensures that the material to be processed is initially guided into a narrowing gap in the area of the inlet section 9a. In the area of the welding section 9b, the gap is then minimal and is kept essentially constant in the area of the welding section. In this case, the welding is mainly carried out by the welding section 9b, but the inlet section 9a can already contribute to the welding at its end facing the welding section 9b.

[0057] Finally, FIGS. 6 and 7 show an alternative embodiment of the processing element 1 according to the invention, which is particularly suitable for producing gatherable materials. For this purpose, at least one thread is guided between two material web sections of the material to be processed, which is connected to the material web sections in sections by the structural elements 4 in a force-fitting or material-fitting manner. The structural elements 4 extend continuously over the entire extent of the anvil 1 in the direction of the longitudinal axis 10. Furthermore, the structural element 4 and thus also the grooves 5 run in a serpentine shape (see FIG. 7). Due to the design shown in FIGS. 6 and 7, the thread is stably connected to the material web sections, while at the same time the friction between the processing element 1 and the material is reduced.

LIST OF REFERENCE SIGNS

[0058] 1 Processing element (anvil) [0059] 2 Carrier surface [0060] 3 Counter-element (sonotrode) [0061] 4 Structural elements [0062] 5 Grooves [0063] 6 Main section [0064] 7, 8 Chamfer sections [0065] 9 Sealing surface [0066] 9a Inlet section [0067] 9b Welding section [0068] 10 Longitudinal axis [0069] 11 Seam selvage