Sonotrode, device and method for ultrasonic machining of workpieces

Abstract

A sonotrode (11) for ultrasonic processing of workpieces, in particular for welding electrical conductors, has at least one projection (14) with a working surface (15) on a circumferential surface (13). The sonotrode (11) can be excited to vibrations with respect to a longitudinal axis (L). The working surface (15) is arranged at an angle (α) with respect to the longitudinal axis of the sonotrode (11).

Description

[0001] The invention relates to a sonotrode, a device and a method for ultrasonic processing of workpieces according to the preamble of the independent claims.

[0002] It is known to machine workpieces by introducing ultrasonic vibrations. Typical applications include joining workpieces by ultrasonic welding. In particular, electrical conductors such as stranded wires or terminals are welded together. For example, WO 2011 / 138404 A1 discloses a so-called torsion sonotrode with which a welded joint can be produced. In this sonotrode, a working surface is provided on a circumferential surface surrounding a torsion axis at a distance from the torsion axis. The working surface is located in a central region of the sonotrode.

[0003] WO 2012 / 069413 A1 also discloses a device for torsional welding of metal parts using ultrasound. A welding surface is arranged at one end of a torsional oscillating sonotrode, which can be set into torsional oscillations by means of one or more converters.

[0004] While these solutions allow for satisfactory welding results in many applications, challenges arise, particularly with larger workpieces, regarding workpiece accessibility and the uniformity of the introduced vibrations. Due to torsional vibrations, the vibration amplitude is not constant along the length of the sonotrode. Especially with long welds extending towards the sonotrode, variations in amplitude occur. Furthermore, the solution according to WO 2011 / 138404 A1 is difficult to use with components that have a relatively large height, such as terminals, because increasing the distance of the weld area from the torsional axis leads to large, vibrating masses.

[0005] The object of the invention is therefore to avoid the disadvantages of the known and in particular to create a sonotrode, a device and a method for ultrasonic machining of workpieces which allow a uniform input of the ultrasonic energy and in particular also enable the machining of large workpieces.

[0006] According to the invention, the problems are solved with sonotrodes, devices and methods with the features of the independent patent claims.

[0007] According to a first aspect of the invention, a sonotrode for the ultrasonic processing of workpieces is proposed. In particular, it is a sonotrode for welding electrical conductors.

[0008] The sonotrode has a circumferential surface and is provided with at least one projection on this circumferential surface. The projection has a working surface.

[0009] The sonotrode can be excited to oscillate about a longitudinal axis. These are preferably torsional oscillations.

[0010] According to the invention, the working surface is arranged at an angle to the longitudinal axis of the sonotrode. This angle is chosen such that the distance of the working surface to the longitudinal axis varies along the longitudinal axis. This inclination of the working surface compensates for the amplitude variation resulting from torsional oscillation. At a torsional node, the amplitude of the torsional oscillation is nearly zero in the circumferential direction. It is maximal at an antinode. The torsional amplitudes on the working surface depend on the distance of the working surface to the longitudinal axis of the sonotrode. The greater the distance to the longitudinal axis, the greater the torsional amplitude in the area of ​​the working surface.The sonotrode according to the invention is therefore preferably designed such that it can be excited to torsional vibrations about its longitudinal axis with a coupling point, as described, for example, in WO 2012 / 069413. Such amplitude compensation could also be advantageous for longitudinal sonotrodes.

[0011] The angle between the working surface and the longitudinal axis of the sonotrode is selected based on the length and radius of the working surface and / or the distance between torsional vibration minima and maxima to achieve the best possible compensation of amplitude changes. Preferably, the angle is between 5° and 35°, more preferably between 10° and 20°, and most preferably approximately 14°. In a specific application, the angle is determined by simulation for a particular geometry such that the amplitude changes along the working surface are minimized.

[0012] Preferably, the sonotrode has a plurality of projections, each with a working surface. The projections are arranged particularly evenly around the circumference of the sonotrode. Preferably, there are two projections. This allows the sonotrode to be reinstalled after being rotated 180 degrees around its axis when it reaches the end of its service life, thus enabling the use of a second, unused working surface.

[0013] The working surface preferably extends over a relatively large length of the sonotrode, typically over 30 to 60 percent and particularly preferably over 45 to 55 percent of the length of the sonotrode, measured in the longitudinal direction of the sonotrode.

[0014] Preferably, the work surface has a structure, in particular in the form of extending grooves running along the longitudinal axis. This increases the energy input into the workpieces.

[0015] Preferably, the sonotrode has a mounting contour for attachment. This mounting contour is typically located in the region of a vibration minimum and adjacent to the back side of the projection. Preferably, the working surface adjacent to the back side of the projection has the greatest distance from the longitudinal axis. This results in the amplitude being most greatly increased adjacent to the vibration minimum due to the greater distance, thus achieving a relatively constant amplitude along the length of the working surface.

[0016] The projection preferably has an undercut extending from the circumferential surface on its back side. Adjoining the undercut is preferably an annular surface extending in a plane perpendicular to the longitudinal axis, which transitions into the working surface. The undercut also aids in compensating for amplitude variations. Irregularities in the amplitude can be homogenized by means of the undercut.

[0017] Furthermore, the work surface preferably has the smallest distance to the longitudinal axis adjacent to an end face of the projection. This also serves to better homogenize the amplitude along the work surface.

[0018] Preferably, the end face has a front section adjacent to the work surface that runs perpendicular to the work surface.

[0019] According to another aspect of the invention, a device for the ultrasonic machining of workpieces is proposed. The device comprises a sonotrode and an anvil. Typically, a sonotrode designed as described above is used. The sonotrode can be set into vibration, particularly torsional vibrations, by means of a converter in a manner known per se. A working space for receiving the workpieces to be machined is formed between the sonotrode and the anvil. The anvil can be a passive component. However, it is also conceivable to excite the anvil itself to ultrasonic vibrations in order to increase the energy input. It is also conceivable to use a second sonotrode as described above. The sonotrode has a circumferential surface on which at least one projection with a working surface is provided.The working surface is arranged at an angle to the longitudinal axis of the sonotrode. This also means that the longitudinal axis of the sonotrode lies at an angle to a contact surface of the anvil and that the sonotrode is installed obliquely in the device according to the invention.

[0020] Preferably, the device can have side limits for laterally limiting the working space in a manner known per se.

[0021] Another aspect of the invention relates to a method for the ultrasonic processing of workpieces, in particular for welding electrical conductors. A device as described above is preferably used. In a first step, workpieces are placed in a working chamber formed between a sonotrode and an anvil. These workpieces can be, for example, several strands that are to be spliced ​​together or joined together to form a node. They can also be a terminal onto which one or more strands are welded. The anvil can serve as a support surface for the terminal. Alternatively, it can form a contour that can be moved in a known manner, by means of which the working chamber can be closed and the workpieces placed therein, such as strands, can be compressed.

[0022] The sonotrode is preferentially excited to torsional vibrations.

[0023] According to a further aspect of the invention, a device for the ultrasonic processing of workpieces, and in particular for welding electrical conductors, is proposed. The device comprises a sonotrode and an anvil. A working space for receiving the workpieces to be processed is formed between the sonotrode and the anvil. The sonotrode has a circumferential surface on which at least one projection with a working surface is formed. The sonotrode can be excited to vibrations with respect to a longitudinal axis. According to the invention, the projection is arranged adjacent to the end of the sonotrode with respect to its longitudinal direction. Because the projection is arranged adjacent to the end of the sonotrode, the device can also be used for welding components with a relatively high overall height, such as terminals.Therefore, parts of the workpiece to be welded that are taller can be arranged laterally to the side of the sonotrode, in a sense extending its axis.

[0024] Preferably, the sonotrode is provided with at least one projection at each of its two ends. This allows for a symmetrical design of the sonotrode, resulting in an optimized vibration pattern. It is particularly preferred that the sonotrode has a plurality of projections, each with a working surface, at one end, or preferably at both ends. This allows unused working surfaces to be used when the working surfaces become worn by rotating the sonotrode, as shown, for example, for a centrally arranged working surface in EP 1 566 233.

[0025] In a preferred embodiment, the sonotrode has a balancing mass on its circumferential surface in a central section. This additional mass allows the distances between vibration minima to be reduced. This enables the sonotrode according to the invention to be mounted in the same manner as the sonotrode shown in WO 2011 / 138404. The distances between mounting structures at a vibration minimum can thus be adapted to existing devices.

[0026] Preferably, the counterweight is also rotationally symmetrical with respect to the longitudinal axis. Furthermore, the counterweight preferably has an outermost surface that is located at a distance from the longitudinal axis that is smaller than the distance of the working surface from the longitudinal axis. This allows the sonotrode according to the invention to be integrated into the device particularly easily.

[0027] Preferably, the sonotrode has at least one, and preferably two, mounting contours in a vibration minimum for securing the sonotrode. Preferably, a mounting contour is provided between the at least one projection and the counterweight. Preferably, if the sonotrode has projections at both ends, mounting contours are provided on both sides of the counterweight. If the projections are on only one side, preferably two mounting contours are provided on both sides of the counterweight.

[0028] Another aspect of the invention relates to a sonotrode for a device as described above. The sonotrode has at least one projection with a working surface on a circumferential surface. The sonotrode can be excited to vibrations about its longitudinal axis, in particular torsional vibrations. According to the invention, the projection is arranged adjacent to the end of the sonotrode. Preferably, the sonotrode is designed as described above in connection with the device, in particular with a projection at both its ends and preferably with several projections at each end, as well as with a counterweight.

[0029] Another aspect of the invention relates to a method for the ultrasonic processing of workpieces, in particular for welding electrical conductors. In this process, a sonotrode as described above is used. First, workpieces are placed in a working chamber formed between a sonotrode and an anvil. Preferably, the workpieces are a terminal and at least one strand.

[0030] The sonotrode is then excited to torsional vibrations about its longitudinal axis. A working surface on a projection extending from a circumferential surface of the sonotrode is set into vibration. This working surface is located adjacent to the end of the sonotrode with respect to its longitudinal axis. The workpieces are placed in the working space such that a portion of at least one of the workpieces extends laterally from the sonotrode along an extension of its axis.

[0031] The invention is explained in more detail below using exemplary embodiments and with reference to the drawings. The drawings show: Fig. 1: A schematic representation of a first embodiment of a device according to the invention. Fig. 2: A perspective view of a sonotrode according to the device in Fig. 1. Fig. 3: An enlarged view of a projection of the sonotrode according to Fig. 2. Fig. 4: A perspective view of the sonotrode according to Fig. 2 and Fig. 3 in assembled form. Fig. 5: A cross-section through the sonotrode according to Fig. 2, Fig. 3 to Fig. 4. Fig. 6: A top view of the sonotrode according to Fig. 2, Fig. 3, Fig. 4 to Fig. 5. Fig. 7: A description of the state of the art. Fig. 8: A schematic representation of part of a sonotrode according to a second embodiment of the invention. Fig. 9: A representation of a complete sonotrode according to the second embodiment of the invention and Fig. 10: the sonotrode according to Fig. 9 in an assembled arrangement within a device and Fig. 11: a representation of an alternative sonotrode according to the second embodiment.

[0032] Fig. Figure 1 shows a device 10 for welding stranded wires. The device 10 has a sonotrode 11. A projection 14, comprising a working surface 15, is arranged on a circumferential surface 13 of the sonotrode 11. The working surface 15, together with an anvil 12 and two side stops 16a, 16b, forms a working chamber A for the stranded wires. The working chamber A can be opened and closed in a manner known per se, so that the stranded wires inserted therein can be closed and compressed by moving the anvil 12 in a vertical direction and by moving the side stops 16a, 16b in a horizontal direction. This compacts the inserted stranded wires. The sonotrode 11 can be excited to torsional vibrations about a longitudinal axis L in a manner known per se. The working surface 15 is arranged at an angle α with respect to the longitudinal axis L.Therefore, the sonotrode 11 is installed obliquely in the device 10, so that its longitudinal axis L also runs at an angle α with respect to a horizontal.

[0033] Fig. Figure 2 shows a perspective view of sonotrode 11 from Fig. 1. The sonotrode 11 has two projections 14, which are evenly spaced on the circumferential surface 13, offset by 180° in the circumferential direction. The working surface 15 is provided with grooves 17.

[0034] The projection 14 has a rear face 19 that faces a mounting contour 18 for attaching the sonotrode. The mounting contour 18 is located in a region of torsional vibration minimum of the sonotrode 11. An undercut 20 is located on the rear face 19 of the projection 14. The projection 14 transitions from the undercut 20 via an annular surface 21 into the working surface 15. The annular surface 21 lies in a plane that is perpendicular to the longitudinal axis L.

[0035] Parallel to the longitudinal axis L there are also positioning grooves 29.

[0036] On the side of the back side 19 opposite the longitudinal axis L, the projection 14 has an end face 22.

[0037] Fig. Figure 3 shows an enlarged section of one of the projections 14 of the sonotrode. Fig. 2. Identical reference numerals denote identical parts. A circumferential groove 25 is located between the undercut 20 and the mounting contour 18. The undercut 20 serves to achieve the most uniform amplitude possible over its entire length. The undercut 20 transitions into the groove 25, which forms a radius that is chosen to be as large as possible to reduce mechanical stress.

[0038] Fig. Figure 4 shows a perspective view of a mounted sonotrode 11. The sonotrode 11 is secured via the mounting contour 18 (see Fig. 2 and Fig. 3) The sonotrode 11 is mounted in a vibration-isolated manner in a mounting 30 of the device 10. The sonotrode 11 is also connected to a coupling piece 32, which has a mechanical connection interface 31 for connection to converters 34 in a manner known per se. Ultrasonic vibrations can be introduced into the sonotrode in a direction perpendicular to the longitudinal axis L using the converters 34 in a manner known per se, so that the sonotrode 11 is excited to torsional vibrations about the longitudinal axis L.

[0039] Fig. 5 shows a side view of the [unclear text] in the Fig. 2, Fig. 3 to Fig. 4 described sonotrode 11. The sonotrode 11 has a threaded bore 33 for connection with the coupling piece 32 (see Fig. 4) on. On the end face 22, the projection 14 has an end section 23 adjoining the working surface 15, which runs perpendicular to the working surface 15. The sonotrode also has a recess 24 on the side facing away from the threaded bore 33, viewed in the axial direction L. The recess 24 forms a space for receiving one of the side limiters 16a, 16b of the welding chamber when the sonotrode 11 and the anvil 12 approach each other.

[0040] The working surface 15 has a length l1, typically about 40 mm, when projected onto the longitudinal axis L. The length l2 of the sonotrode is typically about 80 mm. The distance between the working surface 15 and the circumferential surface 13 increases continuously from a minimum distance b to a maximum distance a, such that the working surface 15 is drawn at an angle α of 14° to the longitudinal axis L. This means that the working surface lies on a radius relative to the longitudinal axis L that increases from about 34.4 mm to 44 mm.

[0041] Fig. Figure 6 shows a top view of the sonotrode according to Fig. 2, Fig. 3, Fig. 4 to Fig. 5. A threaded bore 33 is arranged on a connecting surface 28, which can be brought into contact with the coupling piece 32. The projections 14 have grooves 17. Longitudinally extending positioning grooves 29 serve to align and secure the sonotrode 11.

[0042] Fig. Figure 7 illustrates the prior art with a device 5 featuring a known sonotrode 1, such as that described in WO 2011 / 128404. The sonotrode 1 has a projection 3 with a working surface 2. The sonotrode 1 is used for welding workpieces W, exemplified as a terminal, onto which stranded wires (not shown) are to be welded. Due to the relatively large height of the terminal W, the working surface 2 cannot make contact with the weld point 4. Increasing the radius of the working surface 2 is not feasible because, at a certain frequency and vibration mode, this would result in an excessively long sonotrode 1. Furthermore, if the working surface radius is too large, vibration under full load would cause the projection 3 to bend circumferentially.

[0043] Fig. Figure 8 shows a first embodiment of a Fig. 7 modified sonotrode 51. The sonotrode 51 has a circumferential surface 53. Two projections 54 extend from the circumferential surface 53 at both ends, each provided with a working surface 55. The working surface 55 runs parallel to a longitudinal axis LL, about which the sonotrode can be excited to torsional vibrations. The projection 54 is located directly adjacent to the end E of the sonotrode 51. Due to this arrangement, unlike in the prior art, the sonotrode 51 can readily be used for welding components W with a large overall height without having to increase the radius r1 of the working surface 55. The sonotrode has an undercut 56 between the working surface 55 and the circumferential surface 53. Thanks to this undercut 56, the amplitude can be corrected, so that a chamfer according to the embodiments described above can be dispensed with.

[0044] Fig. Figure 9 shows a perspective view of the sonotrode from Fig. 8. The sonotrode 51 has two projections 54 at each of its two ends, each with a working surface 55. A counterweight 59 is also provided centrally. The counterweight 59 extends from a central section 60. The counterweight 59 has a radius r2 that is smaller than the radius r1 of the working surface 55 from the longitudinal axis LL. Between the counterweight 59 and the projection 54, there are mounting contours 58 on both sides for mounting the sonotrode 51. The mounting contours 58 are arranged in the region of a torsional vibration minimum. The sonotrode 51 is rotationally symmetrical overall with respect to the longitudinal direction LL and mirror-symmetrical with respect to a median plane passing through the counterweight 59.

[0045] Fig. Figure 10 shows a device 50 in which the sonotrode 51 is installed and secured by a mounting 61. The sonotrode 51 forms a working space AA with a support surface 52 of the workpiece W. The support surface 52 serves as an anvil for supporting a stranded wire (not shown). The workpiece W is mounted laterally next to the sonotrode 51 in the longitudinal direction LL of the sonotrode 51.

[0046] Fig. Figure 11 shows an alternative embodiment of a sonotrode 51. Compared to the embodiment according to Fig. 9 here a projection 54 with a working surface 55 is arranged only on one side. Fastening contours 58 are arranged on both sides of a leveling compound 59.

[0047] In the embodiments of the Fig. 8 - 11 the sound is introduced in a manner known per se through an end face 63 of the sonotrode opposite the active working surface 55'. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2011 / 138404 A1 [0002, 0004] WO 2012 / 069413 A1

[0003] WO 2012 / 069413

[0010] EP 1 566 233

[0024] WO 2011 / 138404

[0025] WO 2011 / 128404

[0042]

Claims

[1] Sonotrode (11) for ultrasonic processing of workpieces, in particular for welding electrical conductors, wherein the sonotrode (11) is provided on a circumferential surface (13) with at least one projection (14) with a working surface (15) and wherein the sonotrode (11) can be excited to oscillations with respect to a longitudinal axis (L), characterized by , that the working surface (15) is arranged at an angle (α) with respect to the longitudinal axis of the sonotrode (11). [2] Sonotrode (11) according to claim 1, wherein the sonotrode (11) can be excited to torsional vibrations about the longitudinal axis (L). [3] Sonotrode (11) according to one of claims 1 or 2, wherein the angle (α) is between 5° and 30°, preferably between 10° and 20° and particularly preferably about 14°. [4] Sonotrode (11) according to one of the preceding claims, wherein the sonotrode (11) has a plurality of projections (14) each having a working surface (15), which projections (14) are arranged uniformly around the circumference of the sonotrode (11), in particular two projections (14). [5] Sonotrode (11) according to one of the preceding claims, wherein the working surface (15) extends over a length (l1) of 30% - 60% of the length (12) of the sonotrode (11), preferably 45% - 55%. [6] Sonotrode (11) according to one of the preceding claims, wherein the working surface (15) has a structuring, in particular in the form of grooves (17) extending in a plane passing through the longitudinal axis. [7] Sonotrode (11) according to one of the preceding claims, wherein the sonotrode (11) has a fastening contour (18) for fastening the sonotrode (11), which is arranged adjacent to a rear side of the projection (14) in a region of a vibration minimum. [8] Sonotrode (11) according to claim 7, wherein the working surface (15) adjacent to the rear side (19) of the projection (14) has the greatest distance (a) to the longitudinal axis. [9] Sonotrode (11) according to claim 7 or 8, wherein the projection (14) on the rear side (19) has an undercut (20) extending from the circumferential surface (13) of the sonotrode (11), to which a ring surface (21) preferably extends in a plane perpendicular to the longitudinal axis (L) and merges into the working surface (15). [10] Sonotrode (11) according to one of claims 7 to 9, wherein the working surface (15) adjacent to an end face (22) of the projection (14) has the smallest distance (b) to the longitudinal axis (L). [11] Sonotrode (11) according to claim 10, the end face (22) having an end section (23) extending perpendicular to the working surface (15) adjacent to the working surface (15). [12] Device (10) for ultrasonic processing of workpieces, in particular for welding electrical conductors, wherein the device (10) comprises a sonotrode (11), in particular a sonotrode (11) according to one of claims 1-11, and an anvil (12), wherein a working space (A) is formed between the sonotrode (11) and the anvil (12) for receiving the workpieces to be machined, wherein the sonotrode (11) is provided on a circumferential surface (13) with at least one projection (14) with a working surface (15) and wherein the sonotrode (11) can be excited to oscillations with respect to a longitudinal axis (L), characterized by that the working surface (15) is arranged at an angle (α) with respect to the longitudinal axis of the sonotrode (11). [13] Device (10) according to claim 12, wherein the device (10) has side limiters (16a, 16b) for lateral limitation of the working space (A). [14] Method for ultrasonic processing of workpieces, in particular for welding electrical conductors, in particular with a device (10) according to claim 12 or 13, comprising the steps: - Placing the workpieces into a working space (A) formed between a sonotrode (11) and an anvil (12). - Excitation of the sonotrode (11) with respect to a longitudinal axis, wherein a working surface (15) on a circumferential surface (13) is excited to vibrations, wherein the working surface (15) is arranged at an angle (α) with respect to the longitudinal axis (L) of the sonotrode (11). [15] Method according to claim 14, wherein the workpieces are strands. [16] Method according to one of claims 14 or 15, wherein the sonotrode (11) is excited to torsional vibrations. [17] Method according to any one of claims 14 to 16, wherein the working space is laterally limited by side limiters (16a, 16b). [18] Device (50) for ultrasonic processing of workpieces (W), in particular for welding electrical conductors, wherein the device comprises a sonotrode (51) and an anvil (52), wherein a working space (AA) for receiving the workpieces (W) to be machined is formed between the sonotrode (51) and the anvil (52), wherein the sonotrode is provided on a circumferential surface (53) with at least one projection (54) with a working surface (55) and wherein the sonotrode (51) can be excited to oscillations with respect to a longitudinal axis (LL), characterized by that the projection (54) is located adjacent to the end (E) of the sonotrode. [19] Device (50) according to claim 18, wherein the sonotrode (51) is provided at least one projection (54) at both its ends (E). [20] Device (50) according to claim 18 or 19, wherein the sonotrode (51) has at one end (E), preferably at both ends, a plurality of projections (54) each having a working surface (55), which projections (54) are arranged uniformly around the circumference of the sonotrode (51), in particular two projections (54). [21] Device (50) according to one of claims 18-20, wherein the sonotrode (51) has a compensating mass (59) on its circumferential surface (53) in a central section (60). [22] Device (50) according to claim 21, wherein the balancing mass (59) is rotationally symmetric with respect to the longitudinal axis (LL). [23] Device (50) according to claim 21 or 22, wherein the compensating mass (59) has an outermost surface which has a distance (r2) from the longitudinal axis (LL) that is smaller than the distance (r1) of the working surface (55) from the longitudinal axis (LL). [24] Device (50) according to one of claims 18 to 23, wherein the sonotrode (51) has at least one and preferably two fastening contours (58) for fastening the sonotrode (51), wherein preferably a fastening contour (58) is arranged on both sides of the compensating mass (59). [25] Sonotrode (51), in particular for a device according to any one of claims 18 to 24, wherein the sonotrode is provided on a circumferential surface (53) with at least one projection (54) with a working surface (55) and wherein the sonotrode (51) can be excited to oscillations with respect to a longitudinal axis (LL), characterized by that the projection (54) is located adjacent to the end (E) of the sonotrode. [26] Method for ultrasonic processing of workpieces, in particular for welding electrical conductors, especially with a sonotrode (51) according to one of claims 18-24, comprising the steps: - Inserting the workpieces (W) into a working space (AA) formed between a sonotrode (51) and an anvil (52), wherein the workpieces (W) are preferably inserted into the working space (AA) such that a part of at least one of the workpieces (W) extends laterally to the sonotrode (51) in an extension from its axis. - Excitation of the sonotrode (51) to torsional vibrations with respect to a longitudinal axis (LL), wherein a working surface (55) on a projection (54) extending from a circumferential surface (53) of the sonotrode (51) is excited to vibrations, wherein the working surface (55) is arranged adjacent to the end (E) of the sonotrode (51) with respect to the longitudinal axis (LL) of the sonotrode (51).

Images