Compensation of ultrasonic horn thermal distortion

Abstract

The invention relates to an ultrasonic horn for an ultrasonic welding device, which has an upper part with a length o and a lower part with a length u, which are arranged next to each other on a longitudinal axis of the ultrasonic horn and which have a total length in the direction of the longitudinal axis of u + o, which lower part has a sealing face which is oriented perpendicularly to the longitudinal axis and which is intended to come into contact with the material to be processed. In order to provide an ultrasonic horn for an ultrasonic welding device with which even very thin layers of material can be welded together in a high quality, according to the invention the lower part has a groove, wherein the groove extends from the sealing face to the side of the lower part which is opposite the sealing face, so that the lower part of the ultrasonic horn is divided into segments which are next to each other in the direction perpendicular to the longitudinal axis.

Description

TECHNICAL FIELD

[0001] The present invention relates to a sonotrode for an ultrasonic welding device, the sonotrode having an upper part with a length o and a lower part with a length u, the upper part and the lower part being arranged adjacent to each other on a longitudinal axis of the sonotrode and the total length of the sonotrode in the direction of the longitudinal axis being u + o, the lower part having a sealing face oriented perpendicular to the longitudinal axis, the sealing face being intended to come into contact with a material to be processed. BACKGROUND

[0002] For a long time, ultrasonic welding has been an accepted method when it comes to shape- or material-locking thermoplastic plastics to each other. The range of applications goes from the automotive and electrical industry to the packaging, medical and hygiene industry.

[0003] A typical ultrasonic welding device has an ultrasonic generator, a transducer, an optional horn and a welding tool, which is called sonotrode. The ultrasonic generator generates a high voltage of the desired ultrasonic frequency depending on the applied supply voltage. The electrical vibrations of the ultrasonic generator are then converted into mechanical longitudinal vibrations using the inverse piezoelectric effect of the transducer and the mechanical longitudinal vibrations are transmitted to the horn or the welding tool. The amplitude of the mechanical vibrations can be increased or decreased by means of the horn and the horn is optionally arranged between the transducer and the welding tool. In addition, the horn can also serve to support the vibrating device consisting of the transducer, the horn and the welding tool. The sonotrode finally transmits the mechanical vibrations into the components to be joined as the actual active welding tool. The sonotrode has a sealing face and the sonotrode comes into contact with the material to be processed via the sealing face.

[0004] The mechanical vibrations with a frequency in the ultrasonic range generate frictional heat in the plastics to be joined and excite the molecular movement in the plastics. As a result, the plastics become soft and start to melt, so that the components to be joined together are connected when a certain pressure is applied to the components over a period of time. These components are then fixedly connected to each other on a molecular level.

[0005] The performance of the weld seam in terms of strength, tightness and optical impression depends on various factors in the ultrasonic welding process. On the one hand, the frequency and amplitude of the vibrations used in the welding process play a certain role, on the other hand, the duration and the applied welding force also influence the final result of the welding. In addition, the welding result also depends on the geometry or spatial shape of the welding tool. Therefore, the shape of the welding tool has been preselected so that, for example, a certain welding result can be achieved for the optical impression. One example in this regard is found in, for example, WO 2012 / 107522 A1, which discloses a device for producing a transverse sealing seam.

[0006] For example, various geometries for welding tools are described in "The design of ultrasonic resonators with wide output cross-sections" (P. Derks, Technische Hogeschool Eindhoven, https: / / doi.org / 10.6100 / IR34306).

[0007] However, it is also possible to change the shape of the welding tool, i.e. the ultrasonic horn, during the welding process. During the welding process, there is a temperature difference within the ultrasonic horn, which leads to a non-uniform thermal expansion of the ultrasonic horn material. This leads to a partially convex sealing surface, and depending on the material being welded, the sealing surface has a significant influence on the welding result. Thus, in particular, the uniform welding of very thin material layers, for example nonwovens, for the medical industry or hygiene products is very limited. Fluctuations in the result both in the strength of the weld and in the visual impression of the weld occur during production. This is because, when welding very thin material layers, the distance between the welding tool and the counter tool, between which the material layer is arranged, must be correspondingly small in order to achieve a weld. If this distance is in the range of only a few micrometers, for example, the deformation of the sealing surface of the ultrasonic horn, which is also only in the range of a few micrometers, leads to a (relative) significant local change in the distance between the welding tool and the counter tool. Thus, in some areas, too little pressure is applied to the material to be joined, while in other areas too much pressure is applied.

[0008] In order to solve or minimize this problem, it is known from the prior art to grind the sealing surface, which comes into contact with the material to be processed, concavely. The concave recess of the sealing surface is then raised by the convex thermal expansion of the ultrasonic horn material, so that a flat sealing surface and thus a uniform weld is achieved during the operation of the ultrasonic welding device.

[0009] The disadvantage of this solution is that the deformation is ideally compensated only at a very specific operating point of the ultrasonic welding device. When starting the ultrasonic welding device from a cold state, or when the tool is heated to a greater extent than initially planned, this optimum operating point cannot be reached and thus a uniform weld cannot be achieved.

[0010] Nevertheless, in order to achieve a processing result that is as reproducible as possible, a strong air cooling of the ultrasonic horn is usually used as an alternative or additional solution to this solution in order to keep the over-heating or deformation as low as possible. Furthermore, it is known to equip the ultrasonic horn with cooling channels in the region of the sealing surface in order to keep the temperature of the ultrasonic horn as constant as possible. However, even in this way, a uniform welding of very thin materials cannot be guaranteed. SUMMARY

[0011] It is therefore an object of the present application to provide an ultrasonic horn for an ultrasonic welding device with which even very thin material layers can be welded together with high quality.

[0012] According to the application, this object is achieved by an ultrasonic horn of the above-mentioned type, the lower part of which has a groove which extends from the sealing face to the side of the lower part opposite the sealing face, so that the lower part of the ultrasonic horn is divided into a plurality of segments which are adjacent to one another in a direction perpendicular to the longitudinal axis, the groove has two groove walls, and the spacing between the groove walls narrows towards the sealing face.

[0013] The division of the lower part of the ultrasonic horn results in a reduction of the effects of thermal expansion, whereby the sealing face, which is divided into a plurality of sealing face sections by the groove, does not bend. In other words, all the sealing face sections lie in one plane, simultaneously contact the material to be welded and exert the same pressure on the material to be welded. Even very thin material layers can be welded together, whereas a convex curvature of the sealing face would result in unsatisfactory welding results.

[0014] In one embodiment, the ultrasonic horn is designed such that u > 0.25 o, preferably 0.8 o < u < 1.5 o, more preferably 0.95 o < u < 1.1 o. Ideally, the length o of the upper part corresponds essentially to the length u of the lower part.

[0015] In this case, if the total length o + u of the ultrasonic horn in the direction of the longitudinal axis corresponds to the wavelength λ of the ultrasonic horn excited during the ultrasonic welding process, it results in the boundary between the upper part and the lower part travelling in the range of a vibration node of the excited vibration. The arrangement of the boundary between the upper part and the grooved lower part in a vibration node has the advantage that this is a region of low stress and low strain. Thus, on the one hand, the tension between the individual segments is reduced, but the influence of the segments on the overall vibration behaviour of the ultrasonic horn is also minimised. As a result, the grooves in the lower part have virtually no influence on the vibrations transmitted to the material.

[0016] The grooves in the lower part of the ultrasonic horn according to the application minimise the thermal deformation of the sealing face on the one hand, while also not significantly influencing the vibration behaviour of the ultrasonic horn, thus optimising the overall welding result.

[0017] In a further embodiment, the sealing face is bounded by two opposite side faces of the ultrasonic horn which extend parallel to one another, and the groove forms an angle of < 90°, preferably an angle of between 80° and 87°, with the two side faces of the ultrasonic horn in the region of the sealing face.

[0018] The grooves are arranged at an angle to the side of the ultrasonic welding head which is arranged perpendicular to the feed direction of the material during the welding process, resulting in a uniform welding result over the entire width of the ultrasonic welding head. The width of the ultrasonic welding head is understood to mean the range which is simultaneously in contact with the material to be processed during the welding operation, thus corresponding to the width of the material which is simultaneously processed during the welding operation. If the grooves were arranged perpendicular to the side, i.e. parallel to the feed direction, this would result in the sealing face having regions which are not welded. This would affect the tightness and the visual impression of the weld achieved. If the grooves are arranged at an angle to the side, however, welding takes place over the entire width of the ultrasonic welding head.

[0019] In this embodiment, it is not necessary for the entire groove to be arranged at an angle. It is sufficient if the lower part of the groove which adjoins the sealing face is arranged at an angle. Such a design offers the advantage of easier manufacture in terms of manufacturing technology.

[0020] According to the application, the groove has two support walls, the spacing between which narrows towards the sealing face, this narrowing being preferably stepped, and the spacing at the sealing face being particularly preferably less than or equal to 1 mm, preferably less than or equal to 0.5 mm, more preferably less than or equal to 0.3 mm.

[0021] The narrowing of the groove towards the sealing face offers the advantage that only a small area of the sealing face is interrupted by the groove when viewed from the surface angle. As a result, the influence of the groove on the welding result is minimised as far as possible (apart from the compensation of thermal expansion).

[0022] In a further embodiment, the end of the groove which faces away from the sealing face has a widening, the sealing face being preferably delimited by two opposite sides of the ultrasonic welding head which extend substantially parallel to one another, and the widening being circular when viewed in the plane of the two opposite sides of the lower part.

[0023] This widening offers the advantage that the stresses which can build up between the segments as a result of the vibration and thermal deformation of the ultrasonic welding head can be reduced.

[0024] In a further embodiment, a further widening is additionally arranged in the region of the stepped narrowing of the groove. Like the widening at the end of the groove which faces away from the sealing face, the further widening preferably has a circular cross-section in the plane of the two opposite sides of the ultrasonic welding head. This arrangement also counteracts the tension between the individual segments.

[0025] In a further embodiment, the sealing face is delimited by two opposite sides which extend substantially parallel to one another, and by a front face and a back face of the ultrasonic welding head, the width of the lower part between the front face and the back face substantially corresponding to the width of the upper part between the front face and the back face.

[0026] In other words, in this embodiment, at least one of the dimensions of the upper part and the lower part is chosen such that it is substantially the same in the upper part and the lower part. Since preferably the lengths o and u of the upper part and the lower part in the direction of the longitudinal axis are also substantially the same, the extension width of the upper part and the lower part in both dimensions is substantially in line with each other.

[0027] In one embodiment, the extension width of the lower part is smaller than the extension width of the upper part in the third dimension between the opposite sides which extend substantially parallel to each other. In other words, the ultrasonic horn narrows towards the sealing face in the lower part.

[0028] In another embodiment, the extension width of the ultrasonic horn in the lower part is smaller than the extension width in the upper part both between the front face and the back face and between the opposite sides which extend substantially parallel to each other. In this embodiment, the ultrasonic horn narrows in both dimensions towards the sealing face.

[0029] In another embodiment, the number of grooves, and thus the width of the individual segments, is chosen such that the convex thermal deformation of the ultrasonic horn in the region of the sealing face is smaller than 3 μm, preferably smaller than 2 μm. The deformation is measured along a direction parallel to the longitudinal axis between the edge of the sealing face and the range of the ultrasonic horn in the middle of the sealing face.

[0030] In another embodiment, the lower part comprises a plurality of grooves, each groove comprising two groove walls, the width of the segment between two adjacent groove walls of two adjacent grooves being at most (u+o) / 3, preferably (u+o) / 4, more preferably (u+o) / 6.

[0031] It will be understood that even in embodiments with only one groove, the width of the segment between the groove wall and the front face or the back face of the ultrasonic horn can be at most (u+o) / 3, preferably (u+o) / 4, more preferably (u+o) / 6.

[0032] The number of grooves thus depends on the total width of the ultrasonic horn between the front face and the back face of the ultrasonic horn and the length u of the lower part and the length o of the upper part. Since preferably the lengths o and u of the upper part and the lower part are chosen in dependence on the wavelength of the excitation of the ultrasonic horn, the number of grooves depends on the total width of the ultrasonic horn and the wavelength of the excitation of the ultrasonic vibrations.

[0033] The total number of grooves influences the vibration response of the ultrasonic horn. The number of grooves must therefore be chosen such that on the one hand a sufficient compensation of the thermal deformation is achieved, but on the other hand the vibration behaviour of the ultrasonic horn itself is influenced as little as possible.

[0034] In another embodiment, the sealing face is bounded by two side faces of the sonotrode which extend substantially parallel to each other and by a front face and a back face of the sonotrode, the front face being arranged at an angle of < 90° to the two opposite side faces at least over the sealing face, and the back face also preferably being arranged at an angle of < 90° to the two opposite side faces at least over the sealing face.

[0035] The arrangement of the front face and preferably also of the back face at an angle of < 90° to the two opposite side faces offers the advantage that several sonotrodes according to the application can be arranged next to each other without destroying the welding in the direction of the processing width in order to increase the processing width of the ultrasonic welding device. The angular arrangement of the front face and of the back face is therefore based on the same considerations as the angular arrangement of the slots in the lower part of the sonotrode. In particular, it is not necessary in this case either for the entire front face or back face to extend at an angle to the two opposite side faces. Rather, only the arrangement of the front face and of the back face in the region of the sealing face is important. The regions of the front face and of the back face which do not directly adjoin the sealing face can also be arranged at any other angle to the two opposite side faces.

[0036] In another embodiment, the upper part of the sonotrode comprises at least one gap which is not arranged along the extension of the slots of the lower part and / or which has a gap width which is greater than the spacing of the slot walls of the slots.

[0037] The introduction of the gaps into the upper part of the sonotrode has the advantage that the vibration behavior of the sonotrode and the expansion of the sonotrode remain stable during excitation with ultrasonic vibrations in the direction of the processing width. If the sonotrode is excited with ultrasonic vibrations, the sonotrode also expands in the direction perpendicular to the material feed direction, i.e. in the processing width. This effect is already noticeable when the width of the sonotrode exceeds one third of the excitation wavelength of the ultrasonic vibrations.

[0038] Since the gaps are not intended to compensate for thermal deformations, unlike the slots in the lower part, but only for deformations due to ultrasonic vibrations, the gaps can on the one hand be shaped differently, for example more widely, and on the other hand independently of the slots. In particular, there is no connection between the slots of the lower part and the gaps of the upper part.

[0039] In another embodiment, a support for supporting the sonotrode in the ultrasonic welding device is provided, which support is arranged on the section of the lower part of the sonotrode.

[0040] The support of the sonotrode on the section of the lower part offers the advantage that the vibration behavior of the sonotrode is substantially not influenced by the support. If the support is placed in a region of the lowest vibration amplitude, little readjustment of the position of the sonotrode will be necessary in order to maintain a constant processing distance between the sonotrode and the material to be processed.

[0041] If the support is arranged on the lower section, the influence of thermal distortion is also lower, since there is less ultrasonic horn material between the support and the material to be processed that can thermally expand. In addition, the thermal expansion is compensated by the groove in the lower section, so that depending on the application, the position of the ultrasonic horn relative to the material to be processed can be readjusted within a significantly smaller range or not at all.

[0042] The potential problem of the present application can be further solved by a method for ultrasonic processing of a material, the method comprising the following steps:

[0043] a) providing an ultrasonic horn according to the above,

[0044] b) providing a counter tool having a sealing surface,

[0045] c) arranging the material between the sealing surface of the ultrasonic horn and the sealing surface of the counter tool,

[0046] d) exciting the ultrasonic horn with ultrasonic vibrations having a wavelength λ,

[0047] e) transmitting the ultrasonic vibrations to the material.

[0048] In another embodiment of the method according to the present application, the following applies to the wavelength λ:

[0049] 0.8(u+o) < λ < 1.2(u+o), preferably

[0050] 0.9(u+o) < λ < 1.1(u+o).

[0051] Thus, preferably, the total length u+o of the ultrasonic horn in the longitudinal axis direction essentially corresponds to the wavelength with which the ultrasonic horn is excited. In this case, the ultrasonic horn is also referred to as a lambda ultrasonic horn.

[0052] In particular, in one embodiment, 0.4λ < u < 0.6λ, preferably λ / 2 = u. In other words, the extension width of the groove in the longitudinal axis direction corresponds to half the wavelength. Since the groove ends at a vibration node of the ultrasonic vibrations, this also provides an advantage with regard to the vibration behavior of the ultrasonic horn. In this case, the groove has virtually no influence on the vibration behavior of the ultrasonic horn and only compensates for thermal distortion of the ultrasonic horn.

[0053] In another embodiment of the method according to the present application, in step e) the material is moved between the sealing surface of the ultrasonic horn and the sealing surface of the counter tool at a feed speed v > 0 m / s.

[0054] By adjusting the feed rate of the ultrasonic welding process, a welding method is provided that can process tubular and strip materials in a timed or continuous operation. The material to be processed is continuously guided through the welding tool, and ultrasonic processing is performed at specific locations or continuously, depending on the feed rate and stroke, or the design of the welding tool. For example, this method is used in the packaging industry, where tubular materials filled in a product are welded and cut at regular intervals for individual product packaging. Other applications have also been found, such as in the processing of strip nonwoven fabrics, which is primarily processed in a continuous process in the hygiene industry. Attached Figure Description

[0055] Other advantages, features, and possible applications of the invention will become apparent from the following description of embodiments and related drawings. In the drawings, the same reference numerals are used to identify the same elements.

[0056] Figure 1 This is a schematic diagram of the first embodiment of the present invention.

[0057] Figure 2a It shows Figure 1 The diagram shows a top view of the sealing surface of the embodiment.

[0058] Figure 2b It shows Figure 2a A magnified view of the marked area.

[0059] Figure 3a It shows Figure 1 The side view of the embodiment shown.

[0060] Figure 3b It shows Figure 3a A magnified view of the marked area.

[0061] Figure 4 It shows Figure 1 The other side view of the front of the embodiment shown.

[0062] Figure 5 This is a three-dimensional schematic diagram illustrating another embodiment of the ultrasonic welding head according to the present invention.

[0063] Figure 6 This is a schematic diagram illustrating an embodiment of the ultrasonic welding head according to the present invention in an ultrasonic welding apparatus. Detailed Implementation

[0064] Figure 1The illustrated embodiment of the ultrasonic horn 1 according to the application for an ultrasonic welding device can be divided into an upper portion 20 having a length o and a lower portion 10 having a length u. The upper portion 20 and the lower portion 10 are arranged adjacent to each other on a longitudinal axis 100 of the ultrasonic horn 1. The total length of the ultrasonic horn 1 in the direction of the longitudinal axis 100 is u + o. In addition, the length u of the lower portion 10 corresponds to the length o of the upper portion 20. Furthermore, the width 19 of the lower portion 10 corresponds to the width 29 of the upper portion 20.

[0065] It can be seen from Figure 4 that the front face 13 narrows towards the sealing face 11. Thus, the extension width of the upper region of the lower portion 10 of the ultrasonic horn 1 and the upper portion 20 in the plane of the front face 13 is greater than the extension width of the lower region of the lower portion 10 adjoining the sealing face 11. The back face 14 is designed in the same manner as the front face 13.

[0066] In addition, the lower portion 10 has Figure 2a the illustrated sealing face 11, which is oriented perpendicular to the longitudinal axis 100. The sealing face 11 is provided to come into contact with the material 40 to be processed (cf. Figure 6 ). The width 19 corresponds to the width of the ultrasonic processing of the material 40 by the ultrasonic horn 1 according to the application.

[0067] The lower portion 10 of the ultrasonic horn 1 comprises three slots 15, which extend from the sealing face 11 to the side of the lower portion 10 opposite the sealing face 11. The slots 15 have two slot walls spaced apart from each other at a distance 17 (cf. Figure 2b ).

[0068] According to Figure 3b , it can also be seen that the slots 15 face the sealing face 11 and narrow in a stepped manner. In the region of the stepped narrowing, a widening 18' is arranged, which has a circular cross-section in the plane of the side face 12. In addition, the distance of the slot walls of the region 15' of the slots 15 arranged between the widening 18' and the sealing face 11 is significantly smaller than the distance 17 of the slot walls of the slots 15 above the widening 18'.

[0069] In addition to the widening 18' in the region of the stepped narrowing, the slots 15 also have a further widening 18 arranged at the end of the slots 15 facing away from the sealing face 11. The widening 18 also has a circular cross-section when viewed in the plane of the side face 12 (cf. Figure 3a ).

[0070] By means of the widenings 18, 18', it is possible to avoid or at least reduce stresses which can be formed between the segments 10' as a result of vibrations and thermal expansions of the ultrasonic horn material during operation of the ultrasonic horn 1 of the ultrasonic welding device.

[0071] Figure 2a andFigure 2b It is also shown that the groove 15 includes an angle 16 of 81° in the region of the sealing surface 11 and the side surface 12 of the ultrasonic welding head 1. The side surfaces 12, 12' extend parallel to each other, are arranged opposite to each other, and are adjacent to the sealing surface 11 of the ultrasonic welding head 1. Figure 3a As shown, the groove 15 is arranged at an angle 16 to the side 12 only in a small region 15' a few millimeters away from the sealing surface 11 in the direction of the longitudinal axis 100. In the adjacent region in the direction of the longitudinal axis 100, the groove 15 is arranged perpendicular to the two side surfaces 12, 12'.

[0072] In addition, from Figure 2a As can be seen, in addition to the adjacent sides 12 and 12', the front side 13 and back side 14 of the ultrasonic welding head 1, which are also adjacent to the sealing surface 11, are arranged at an angle of <90° to the side side 12. Therefore, the ultrasonic welding head 1 according to the present invention can be connected to other ultrasonic welding heads to increase the processing width of the ultrasonic welding device.

[0073] The lower part 10 of the ultrasonic welding head 1 is divided into multiple segments 10' that are adjacent to each other in a direction perpendicular to the longitudinal axis 100 by the groove 15. The arrangement of the groove 15 in the lower part 10 of the ultrasonic welding head 1 can reduce the thermal deformation of the sealing surface 11, so that a more uniform welding result can be achieved on the width 19 of the lower part 10.

[0074] Additionally, two gaps 21 with a gap width are arranged in the upper part 20 (see reference). Figure 3a The gap 21 is used to minimize the expansion of the ultrasonic welding head 1 on the width 29 of the upper part 20 during the operation of the ultrasonic welding head 1 of the ultrasonic welding apparatus.

[0075] like Figure 1 As shown in Figure 3, the gap 21 is arranged independently of the groove 15, that is, it is not arranged along the extension of the groove or along the common line, and the gap 21 also has a larger gap width because it compensates for the different deformation effects of the ultrasonic welding head 1 through the gap 21 rather than through the groove 15.

[0076] at last, Figures 1-4 The illustrated embodiment includes a support member 30 arranged in the region of segment 10' of the lower part 10.

[0077] Figure 5 The embodiment of the ultrasonic welding head 1 according to the present invention shown is as follows: Figures 1-4 The difference in the embodiment shown is that the support member 30 is not arranged in the lower part 10, but in the upper part 20.

[0078] exist Figure 6 middle, Figure 5The illustrated embodiment of the ultrasonic horn 1 is shown schematically in an ultrasonic welding device. Between the ultrasonic horn 1 and a counter tool 50, a material 40 to be processed is arranged. The material 40 is moved in a feed direction 101 between the ultrasonic horn 1 and the counter tool 50 at a feed speed v > 0 m / s.

[0079] During operation of the ultrasonic welding device, the ultrasonic horn 1 is excited by ultrasonic vibrations with a wavelength λ, and the ultrasonic vibrations are transmitted via the sealing face 11 to the material 40. By means of the ultrasonic vibrations, the material 40 is pressed against the sealing face 51 of the counter tool 50, so that the transmitted ultrasonic vibrations ultrasonically process the material 40. The material 40 can be, for example, a multilayer nonwoven fabric which is joined together in an adhesive connection. When the ultrasonic horn 1 impinges on the nonwoven fabric 40, the nonwoven fabric begins to melt due to the generated frictional heat and is joined to the material layer arranged therebelow.

[0080] The overall length o + u of the ultrasonic horn 1 is chosen such that it substantially corresponds to the wavelength λ of the excited ultrasonic vibrations. In addition, the length of the groove 15, i.e. the length u of the lower part 10, corresponds to half the wavelength λ.

[0081] By choosing these dimensions, it can be ensured that the groove 15 optimally compensates for the thermal deformation of the sealing face 11, but at the same time, the vibration behavior of the ultrasonic horn 1 is not significantly affected. Thus, by means of the ultrasonic horn 1 according to the application, even very thin layers of material 40 can be uniformly welded together using ultrasonic vibrations or conventionally processed.

[0082] 1 ultrasonic horn

[0083] 10 lower part

[0084] 10' section

[0085] 11 sealing face of the ultrasonic horn

[0086] 12, 12' opposite side faces extending parallel to one another

[0087] 13 front face

[0088] 14 back face

[0089] 15 groove

[0090] 15' part of the groove arranged toward the sealing face

[0091] 16 angle

[0092] 17 pitch of the groove walls

[0093] 18, 18' widening

[0094] 19 width of the lower part

[0095] 20 upper portion

[0096] 21 gap

[0097] 29 width of the upper portion

[0098] 30 support

[0099] 40 material

[0100] 50 counter tool

[0101] 51 sealing surface of the counter tool

[0102] 100 longitudinal axis

[0103] 101 feed direction

Claims

1. An ultrasonic horn (1) for an ultrasonic welding device, the ultrasonic horn (1) having an upper part (20) with a length o and a lower part (10) with a length u, the upper part (20) and the lower part (10) being arranged adjacent to each other in a longitudinal axis (100) of the ultrasonic horn (1) and the total length of the ultrasonic horn (1) in the direction of the longitudinal axis (100) being u + o, the lower part (10) having a sealing face (11) oriented perpendicular to the longitudinal axis (100), the sealing face (11) being intended to come into contact with a material (40) to be processed, characterized in that, The lower part (10) has a groove (15), wherein the groove (15) extends from the sealing face (11) to a side of the lower part (10) opposite the sealing face (11) such that the lower part (10) of the ultrasonic welding horn (1) is divided into segments (10') adjacent to each other in a direction perpendicular to the longitudinal axis (100), the groove (15) has two groove walls, and a spacing (17) between the groove walls narrows towards the sealing face (11).

2. The ultrasonic horn (1) according to claim 1, wherein u > 0.25 o.

3. Ultrasonic horn (1) according to claim 2, wherein 0.8 o < u < 1.5 o.

4. The ultrasonic horn (1) according to claim 2, wherein 0.95 o < u < 1.1 o.

5. Ultrasonic horn (1) according to any one of claims 1-4, wherein The sealing face (11) is delimited by two opposite side faces (12, 12') of the ultrasonic welding horn (1) extending substantially parallel to each other, and the groove (15) forms an angle (16) of < 90° with the two side faces (12, 12') of the ultrasonic welding horn (1) in the region of the sealing face (11), respectively.

6. Ultrasonic horn (1) according to claim 5, wherein The angle (16) is between 80° and 87°.

7. The ultrasonic horn (1) according to any one of claims 1-4, wherein The narrowing is stepped.

8. Ultrasonic horn (1) according to claim 7, wherein The spacing (17) is less than or equal to 1 mm.

9. Ultrasonic horn (1) according to claim 7, wherein The spacing (17) is less than or equal to 0.5 mm.

10. The ultrasonic horn (1) according to claim 7, wherein The spacing (17) is less than or equal to 0.3 mm.

11. Ultrasonic horn (1) according to any one of claims 1-4, wherein The groove (15) has a widening (18) at an end facing away from the sealing face (11).

12. Ultrasonic horn (1) according to claim 11, wherein The sealing face (11) is delimited by two opposite side faces (12, 12') of the ultrasonic welding horn (1) extending substantially parallel to each other, and wherein the widening (18) is circular when viewed in the plane of the two opposite side faces (12, 12').

13. The ultrasonic horn (1) according to any one of claims 1-4, wherein, The sealing face (11) is delimited by two opposite side faces (12, 12') extending substantially parallel to each other, and by a front face (13) and a back face (14) of the ultrasonic welding horn (1), wherein a width (19) of the lower part (10) between the front face (13) and the back face (14) substantially corresponds to a width (29) of the upper part (20) between the front face (13) and the back face (14).

14. The ultrasonic horn (1) according to any one of claims 1-4, wherein, The lower part (10) has a plurality of grooves (15), each groove (15) having two groove walls, a width of the segment between adjacent two groove walls of adjacent two grooves (15) is at most (u + o) / 3.

15. Ultrasonic horn (1) according to claim 14, wherein A width of the segment between adjacent two groove walls of adjacent two grooves (15) is at most (u + o) / 4.

16. The ultrasonic horn (1) according to claim 14, wherein A width of the segment between adjacent two groove walls of adjacent two grooves (15) is at most (u + o) / 6.

17. The ultrasonic horn (1) according to any one of claims 1-4, wherein The sealing face (11) is delimited by two opposite side faces (12, 12') extending substantially parallel to each other, and by a front face (13) and a back face (14) of the ultrasonic welding horn (1), wherein the front face (13) is arranged at an angle of less than 90° to the two opposite side faces (12, 12') at least on the sealing face (11).

18. The ultrasonic horn (1) according to claim 17, wherein The back face (14) is also arranged at an angle of less than 90° to the two opposite side faces (12, 12') at least on the sealing face (11).

19. The ultrasonic horn (1) according to any one of claims 1-4, wherein The upper part (20) of the ultrasonic welding horn (1) has at least one gap (21), wherein the gap (21) is not arranged along the extension of the groove (15) of the lower part (10) and / or wherein the gap (21) has a gap width which is greater than the spacing (17) of the groove walls of the groove (15).

20. The ultrasonic horn (1) according to any one of claims 1-4, wherein, A support (30) for holding the ultrasonic welding horn (1) in an ultrasonic welding device is provided, which support (30) is arranged on the section (10') of the lower part (10) of the ultrasonic welding horn (1).

21. A method for ultrasonic processing of a material (40), comprising the following steps: a) providing an ultrasonic welding horn (1) according to any one of claims 1 to 20, b) providing a counter tool (50) having a sealing face (51), c) arranging the material between the sealing face (11) of the ultrasonic welding horn (1) and the sealing face (51) of the counter tool (50), d) exciting the ultrasonic welding horn (1) with ultrasonic vibrations having a wavelength λ, e) transmitting the ultrasonic vibrations to the material (40).

22. The method of claim 21, wherein, The following applies for the wavelength λ, 0.8(u+o) < λ < 1.2(u+o).

23. The method of claim 21, wherein, The following applies for the wavelength λ, 0.9(u+o) < λ < 1.1(u+o).

24. The method of claim 22 or 23, wherein, 0.4λ < u < 0.6λ.

25. The method of claim 24, wherein, λ / 2 = u.

26. The method of any one of claims 21 to 23, wherein, In step e), the material (40) is passed between the sealing face (11) of the ultrasonic welding horn (1) and the sealing face (51) of the counter tool (50) in a feed direction (101) at a feed speed v > 0 m / s.

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