BÖRDEL SONOTRODE

Description

[0001] The present invention relates to a sonotrode for flanging an edge of a container.

[0002] It is common practice to crimp an edge on many containers. Crimping involves bending the edge over. Often, the bending angle is significantly greater than 90°.

[0003] EP 0 002 833 discloses a method for producing a flanged edge. The corresponding flanging tools result in a compression load on the flanged area of ​​the edge, which frequently leads to damage to the edge or undefined buckling of the material. DE 21 59 930 A1, which forms the basis for the preamble of the independent claims, US 3 972 758 A, and US 5 221 028 A also disclose corresponding tools, but these do not enable a clean and reliable bending of the edge.

[0004] It is therefore an object of the present invention to provide a device for flanging an edge of a container, with which a reliable bending of the edge is possible.

[0005] This problem is solved by a sonotrode according to claim 1 or claim 3.

[0006] According to the invention, the flanging of an edge of a container is carried out using a sonotrode which is excited by an ultrasonic vibration and which has an end face which is provided to come into contact with the edge of the container during a relative movement along a longitudinal axis of the sonotrode, wherein the end face has a flanging section which at least sectionally encloses an angle with the longitudinal axis which is greater than 0° and less than 90° and is provided to come into contact with the edge to be flanged.

[0007] According to the invention, the flanging section is thus designed to bend the edge, which is moved longitudinally along the longitudinal axis during processing, outwards or inwards. It has been shown that this bending can be carried out surprisingly easily and without damaging the edge due to the ultrasonic vibration. Furthermore, the edge does not kink at undesirable points.

[0008] In a preferred embodiment, the flanging section has a concave curved section which is designed to come into contact with the contact edge to be flanged.

[0009] The concave curved section allows the edge to be continuously bent further outwards or inwards as it moves along the flanged section. According to the invention, the end face has a groove in which the flanged section is arranged. The groove can have two opposing groove walls and a groove base connecting the grooves, which are designed such that the edge of the container is first guided along one groove wall and bent outwards or inwards, then guided over the groove base, which is preferably concavely curved, to bend the edge further outwards or inwards, and finally guided along the second groove wall, so that the edge is bent by significantly more than 90°, preferably more than 135°.

[0010] According to the invention, the end face has an inner end face section and an outer end face section, the inner end face section being separated from the outer end face section by the groove. In other words, the groove is closed and its shape essentially corresponds to the dimensions of the container edge. Thus, the groove can be, for example, circular, square, rectangular, or kidney-shaped when viewed along the longitudinal axis.

[0011] A particularly preferred embodiment is one in which, in an axial direction perpendicular to the end face, either the inner end face section projects beyond the outer end face section or the outer end face section projects beyond the inner end face section.

[0012] According to the invention, the groove comprises a wall adjoining the inner end face section, a wall adjoining the outer end face section, and a groove base connecting the two walls of the groove, wherein one wall of the groove has a bead that preferably extends along the entire length of the groove. It has been shown that the bead significantly improves material guidance during flanging.

[0013] In another preferred embodiment, the wall adjoining the outer end face section is inclined relative to the longitudinal axis.

[0014] Alternatively, it can also be advantageous if the wall adjoining the end face section that is set back longitudinally relative to the other end face section is inclined relative to the longitudinal axis.

[0015] According to the invention, the groove has a plurality of recesses and / or projections, preferably with at least 20 recesses and / or projections being provided.

[0016] The arrangement of the recesses and protrusions improves the bending behavior of the edge during flanging.

[0017] The recesses and / or projections are preferably identical in shape and have an extent a in the direction of the groove, with adjacent recesses and / or projections spaced apart from each other by a distance b in the direction of the groove. In a preferred embodiment, the distance b corresponds approximately to the extent a of the recesses and / or projections in the direction of the groove. In particular, preferably 0.9 x a < b < 1.1 x a.

[0018] In a further preferred embodiment, the groove, viewed in cross-sectional view perpendicular to the end face, has a concavely curved groove base, wherein the concavely curved section preferably has a semicircular cross-section, and particularly preferably the semicircular cross-section has a radius of curvature between 1 and 1.5 mm. In a further preferred embodiment, the radius of curvature is selected to be at least three times the thickness of the material edge to be flanged.

[0019] The present invention also relates to an ultrasonic welding device for flanging and welding the edge of a container, comprising a sonotrode of the type described and a counter-tool. As already described, the sonotrode is designed to be moved in the direction of the longitudinal axis during the flanging process. The counter-tool is arranged such that the flanged edge comes into contact with the sonotrode and the counter-tool during the welding process.

[0020] In a preferred embodiment of the ultrasonic welding device, a sonotrode is used in which, in an axial direction perpendicular to the end face, either the inner end face section projects beyond the outer end face section or the outer end face section projects beyond the inner end face section.The sonotrode is designed to be moved back and forth between two positions, namely a starting position and a welding position, wherein the counter tool has a sealing surface which, in the welding position, is arranged opposite the groove wall which adjoins the end face section that protrudes from the other end face section, so that in the welding position, when the inner end face section protrudes from the outer end face section, the inner end face section is at least partially arranged within a cavity of the counter tool, and, when the outer end face section protrudes from the inner end face section, the counter tool is at least partially arranged within a cavity of the sonotrode.In other words, the sealing surface of the counter tool in the welding position is spaced in a direction perpendicular to the longitudinal axis from the wall of the groove that adjoins the end face section which projects in the direction of the longitudinal axis relative to the other end face section.

[0021] In a preferred embodiment, a gap remains in the welding position between the sealing surface of the counter tool and the groove wall adjoining the end-face section that protrudes relative to the other end-face section. Preferably, the gap is conical in a cross-sectional view parallel to the longitudinal direction. This has the advantage that, during the relative movement between the sonotrode and the counter tool, the crimped section is pressed into the gap.

[0022] A method for flanging the edge of a container is also described, in which an ultrasonic welding device as described above is used, wherein the sonotrode is moved longitudinally towards the counter tool from a starting position via a flanging position to a welding position, wherein the container is arranged such that the edge does not touch the sonotrode in the starting position, comes into contact with the flanging section of the sonotrode in a flanging position, and in the welding position the flanged edge is arranged between the sealing surface of the counter tool and a sealing surface of the sonotrode.

[0023] In a preferred embodiment of the method, the container has a shell element and a lid element enclosed by the shell element, wherein the shell element forms the edge of the container.

[0024] For example, it is possible in a first step to attach the lid element to the inner surface of a hollow cylinder formed by the shell element and then to crimp the protruding edge of the shell element as described.

[0025] Further advantages, features and applications of the present invention will become clear with reference to the following description of a preferred embodiment and the accompanying figures. These show: Figure 1 a schematic representation of the conditions in the flanging process according to the invention, Figure 2 a cutaway side view of a first embodiment of a sonotrode according to the invention, Figure 3 a cutaway partial enlargement of the embodiment from Figure 2, Figures 4-8 different views of a second embodiment of the sonotrode according to the invention.

[0026] Figure 1Figure 1 is a schematic representation of the conditions during the flanging process according to the invention. The container to be processed has a shell element 1, which can, for example, be hollow cylindrical. A lid element 2 is connected to the shell element 1 on its inner surface.

[0027] One can recognize in Figure 1 , that the outer sections of the lid element 2 are bent upwards so that they run parallel to the shell element 1.

[0028] In a starting position of the sonotrode, which is not visible in the figures, the sonotrode 3 is in the longitudinal direction, i.e. in Figure 1 in a vertical direction, away from the counter tool 4. In this position (not shown), the outer element 1 is not yet bent.

[0029] To fold over the top edge so that it sits approximately in the Figure 1In the position shown, a sonotrode 3 according to the invention is used, which is oriented in the direction of its longitudinal axis, i.e. in Figure 1 The sonotrode 3 moves vertically towards the upper edge of the shell element 1. It has a groove with a first wall 5, a second wall 7, and a groove base 6 which is concavely curved, i.e., provided with a radius of curvature.

[0030] During the relative movement of the sonotrode 3 in the direction of the edge of the shell element 1, i.e. in the vertical direction, the upper edge of the shell element 1 first comes into contact with the wall 5 of the sonotrode, which is inclined relative to the vertical direction, i.e. relative to the longitudinal axis of the sonotrode 3, at an angle of inclination greater than 0 and less than 90°.

[0031] As soon as the upper edge of the cladding element 1 comes into contact with the inclined wall 5, the upper edge of the cladding element 1 is turned inwards, i.e. into Figure 1to the right, bent over.

[0032] As soon as the upper edge comes into contact with the groove base 6, the bending of the upper edge of the shell element 1 is further intensified until the edge of the shell element 1 reaches the other wall 7 and then approximately the one in the Figure 1 takes the position shown.

[0033] In this embodiment, a bead-shaped nose 8 is provided in the wall 7, which pushes the folded edge section outwards. However, the bead 8 is not strictly necessary.

[0034] Also visible is an anvil 4, which has a conical sealing surface 9, such that the distance between the wall 7 and the conical sealing surface 9 is reduced when the sonotrode 3 moves towards the anvil 4, i.e., in the direction of the longitudinal axis. Therefore, the tool not only crimps the upper edge of the container, but also welds the crimped edge section to the lid element 2 and the shell element 1, so that the crimp provides additional support for the lid 2.

[0035] The in Figure 1 The position shown is the welding position. Between the described starting position and the welding position shown lies the flanging position, during which the shell element successively comes into contact with the groove walls 5, 7 and the groove base 6 and is bent over.

[0036] In the Figures 2 and 3Figure 1 shows a sectional view and a partial view of a first embodiment of the sonotrode according to the invention, including the associated anvil 4. The proportions correspond essentially to those shown in Figure 2. Figure 1 The illustration shows that the sealing surface of the sonotrode has an inner end face section 10 and an outer end face section 11, with the inner end face section 10 projecting beyond the outer end face section 11 in the direction of the longitudinal axis. The groove with the flanged section is located between the inner end face section 10 and the outer end face section 11. The anvil 4 is positioned opposite the outer end face section 11.

[0037] The Figures 4-8 show different views of a second sonotrode according to the invention.

[0038] In Figure 4 A perspective view of the sonotrode is shown, with the front face facing upwards. The longitudinal axis runs in Figure 4 also in a vertical direction. Figure 5 Figure 1 shows a top view of the end face, which has an inner end face section 10 and an outer end face section 11. The groove 12 is arranged between the two end face sections 10 and 11, and here has a series of facets, i.e., incorporated recesses, the recesses of which, in this embodiment, have a width wider than the groove width. Figure 6 A side view of the sonotrode is shown, which can be seen to show that the facets extend to the inner groove wall, which connects the groove with the inner end face section 10.

[0039] Figure 7 This is a sectional view of sonotrode 3. Finally, in Figure 8A partial sectional view is shown. It can be seen that the groove differs from the groove in embodiments 2 and 3 essentially in that the inner groove wall 7 is oriented in the direction of the longitudinal axis. Here, too, the material to be flanged is arranged such that the edge of the container first meets the groove wall 5, which is inclined at an angle between 0 and 90° to the horizontal, thus bending the container wall inwards, i.e., in the Figure 8 to the right, it is bent over. The edge then runs over the concave curved section 6, which is formed by the groove base 6, and is folded over towards the groove wall 7.

[0040] By using ultrasound, it is possible to achieve the described flaring with little energy and very reliably with extremely low flaring errors. Reference symbol list

[0041] 1. Shell element 2. Cover element 3. Sonotrode 4. Anvil 5. Groove wall 6. Groove base 7. Groove wall 8. Bead 9. Sealing surface 10. Inner end face section 11. Outer end face section 12. Groove

Claims

1. A sonotrode for crimping an edge of a container having an end face, which is intended to contact the edge of the container during a relative movement along a longitudinal axis, wherein the end face comprises a crimping portion, at least portions of which form an angle with the longitudinal axis that is greater than 0° and is smaller than 90° and is intended to contact the edge being crimped, wherein the end face comprises a groove (12), in which the crimping portion is arranged, and the end face comprises an inner end face portion (10) and an outer end face portion (11), wherein the inner end face portion (10) is separated from the outer end face portion (11) via the groove (12), characterized in that the groove (12) comprises a wall adjoining the inner end face portion (10), a wall adjoining the outer end face portion (12) , and a groove base (6) connecting the two walls of the groove (12), wherein one wall of the groove (12) comprises a bead (7), which preferably extends along the entire groove (12).

2. The sonotrode according to claim 1, characterized in that the crimping portion comprises a concavely curved portion, which is intended to contact the edge being crimped.

3. The sonotrode for crimping an edge of a container having an end face, which is intended to contact the edge of the container during a relative movement along a longitudinal axis, wherein the end face comprises a crimping portion, at least portions of which form an angle with the longitudinal axis that is greater than 0° and is smaller than 90° and which is intended to contact a edge to be crimped, wherein the end face comprises a groove (12), within which the crimping portion is arranged, characterized in that the groove (12) comprises a plurality of recesses and / or protrusions, wherein preferably at least 20 recesses and / or protrusions are provided.

4. The sonotrode according to claim 3, characterized in that the recesses and / or protrusions have the same design and have a length a in the direction of the groove (12), wherein adjacent recesses and / or protrusions are arranged in the direction of the groove (12) at a distance b from one another, wherein 0.9 a < b < 1.1 a is preferable.

5. The sonotrode according to claim 3 or 4, characterized in that the groove (12) comprises a concavely curved groove base (6) in a cross-sectional view perpendicular to the end face, wherein the concavely curved portion preferably comprises a part-circular cross-section, wherein the part-circular cross-section particularly preferably has a radius of curvature of between 1 and 1.5 mm.

6. The sonotrode according to one of claims 3-5, characterized in that the end face comprises an inner end face portion and an outer end face portion, wherein the inner end face portion is separated from the outer end face portion via the groove (12).

7. The sonotrode according to one of claims 3-6, characterized in that the groove (12) comprises a wall adjoining the inner end face portion, a wall adjoining the outer end face portion, and a groove base (6) connecting the two walls of the groove (12), wherein one wall of the groove (12) comprises a bead, which preferably extends along the entire groove (12).

8. The sonotrode according to one of the preceding claims, characterized in that, in an axial direction perpendicular to the end face, either the inner end face portion protrudes over the outer end face portion, or the outer end face portion protrudes over the inner end face portion.

9. An ultrasonic welding apparatus for crimping and welding an edge of a container by means of a sonotrode according to one of claims 1 to 8 and a counter-tool.

10. The ultrasonic welding apparatus according to claim 9, wherein the sonotrode is a sonotrode according to claim 8 and is intended to be moved between two positions, an initial position and a welding position, wherein the counter-tool comprises a sealing surface which, when in the welding position of the groove wall adjoining the end face portion, which protrudes opposite the other end face portion, said sealing surface is arranged opposite such that, when in the welding position, when the inner end face portion protrudes opposite the outer end face portion, the inner end face portion is arranged at least partially within a cavity of the counter-tool and, when the outer end face portion protrudes opposite the inner end face portion, the counter-tool is arranged at least partially within a cavity of the sonotrode.

11. The ultrasonic welding apparatus according to claim 10, characterized in that, when in the welding position between the sealing surface of the counter-tool and the groove wall, which is adjacent to the end face portion protruding opposite the other end face portion, a gap remains, wherein the gap is preferably conical in a cross-sectional view parallel to the longitudinal direction.