Ultrasonic horn and apparatus for machining a workpiece

Abstract

The invention relates to an ultrasonic horn (1) for an ultrasonic welding electrode (30) for machining a workpiece (W) by means of ultrasonic vibrations, having a horn body (10). Longitudinal vibrations (SL) are introduced into the horn body (10) at an ultrasonic introduction side (11) with a first end face (12). A conversion structure (15) is arranged between the ultrasonic introduction side (11) and a coupling side (13) opposite thereto, with which a torsional vibration (ST) having a vibration component in a plane (E) perpendicular to the longitudinal axis (L) can be generated from the longitudinal component (SL).

Description

TECHNICAL FIELD

[0001] The invention relates to an ultrasonic horn and a device for machining a workpiece, having the features of the preamble of the independent claims. BACKGROUND

[0002] It is known to machine workpieces by introducing ultrasonic vibrations. Typical applications are joining workpieces by welding, cutting workpieces or processing powders, for example when sieving.

[0003] Ultrasonic vibrations are generated by a transducer oscillating in the longitudinal direction. In order to join workpieces, in particular workpieces made of metal or plastic, it is known to introduce ultrasonic vibrations into the workpiece in a direction parallel to the surface of the workpiece.

[0004] From WO 95 / 23668 it is known a method and a device for welding metal parts, in which an ultrasonic welding electrode body is placed in torsional vibration. The disadvantage of this construction is that, although a rotational vibration is generated, a longitudinal component is always present, which can lead to damage to the workpiece or to an undesired damping.

[0005] Furthermore, it is also known from US 4,663,556, US 5,662,766, EP 1 103 238, US 2006 / 004396 or US 2011 / 278988 to generate torsional vibrations by introducing longitudinal vibrations.

[0006] Therefore, it is proposed in WO 2012 / 069413 A1 to construct and excite an ultrasonic welding electrode such that the entire ultrasonic welding electrode can be excited to generate a torsional vibration with a negligible small longitudinal vibration component. For this purpose, the vibrations are directed tangentially to the ultrasonic welding electrode body. In this way, the longitudinal component can be avoided and a good welding result is obtained. However, this design is relatively complex.

[0007] Furthermore, the ultrasonic welding electrode is interpreted as a wear part. The insertion of a conversion structure into the ultrasonic welding electrode is relatively complex and, as a result, leads to unnecessarily high costs for the wear part. SUMMARY

[0008] Therefore, it is the task of the invention to avoid the known disadvantages, in particular to establish an ultrasonic component and a device and a method for machining a workpiece, in which vibrations can be generated with as small a longitudinal component as possible in a direction parallel to the surface of the workpiece, which can be manufactured easily and inexpensively and are reliable in operation.

[0009] According to the invention, this task is solved with the ultrasonic horn and the device having the features of the characterizing part of the independent claims.

[0010] The ultrasonic horn according to the application serves to excite an ultrasonic welding horn in order to process a workpiece by means of ultrasonic vibrations. The ultrasonic horn has a horn body with a longitudinal axis. The horn body has an ultrasonic introduction side and a coupling side. The ultrasonic introduction side is provided with a first end face. The coupling side is provided with a second end face.

[0011] On the ultrasonic introduction side, longitudinal vibrations can be introduced into the horn body in a direction parallel to the longitudinal axis.

[0012] The second end face serves to connect the ultrasonic horn and the ultrasonic welding horn.

[0013] Between the ultrasonic introduction side and the coupling side, a conversion structure is arranged. The conversion structure can serve to generate transverse vibrations from the introduced longitudinal vibrations, which have a vibration component in a plane perpendicular to the longitudinal axis.

[0014] According to the application, torsional vibrations can thus be generated from longitudinal vibrations and transmitted into the ultrasonic welding horn in a simple manner. Since the conversion structure is arranged in the horn, the ultrasonic welding horn can be replaced and exchanged very easily. This is particularly the case in the event of wear or when processing workpieces using a plurality of ultrasonic welding horns having different processing surfaces, it is only necessary to arrange the conversion structure in one component, namely the horn.

[0015] Preferably, a damping structure is provided between the conversion structure and the coupling side. The damping structure is designed to reduce the longitudinal vibrations at the coupling side.

[0016] In the conversion structure, the introduced longitudinal vibrations are converted into transverse vibrations in a known technique and manner (see, for example, WO 95 / 23668).

[0017] The damping structure can ensure that the longitudinal vibrations are not or at most only to a negligible extent transmitted to the coupling side. The damping structure is designed in such a way that there is as little damping as possible from the torsional direction, so that the torsional vibrations are transmitted to the coupling side as undamped as possible.

[0018] According to one preferred embodiment, the horn body is configured as a hollow body. However, it is also conceivable for the horn to be configured partially or completely as a solid body. In particular, depending on the intended application, a hollow body or a solid body is preferred.

[0019] The ultrasonic horn preferably has a connection, in particular a thread, at the coupling side for connecting the ultrasonic welding horn. By means of a threaded connection, the connection of the ultrasonic welding horn to the ultrasonic horn can be made particularly easy.

[0020] The ultrasonic horn preferably also has a contour, in particular adjacent to the ultrasonic introduction side, for connecting the ultrasonic horn and a tool of the ultrasonic welding horn. Typically, this is a hexagonal contour. Thereby, the ultrasonic horn and the ultrasonic welding horn can be connected easily in a simple prior art and manner using a conventional hexagonal wrench.

[0021] The amplitude rod body is preferably of rotationally symmetrical construction, in particular with a circular or annular cross-section.

[0022] The torsional ultrasonic welding electrode can be used, for example, for welding plastic parts or metal parts. Typical applications are the welding of sensor holders made of plastic into a bumper of a motor vehicle or the welding of metal wires to one another or to connecting parts. In principle, however, the use of the ultrasonic amplitude rod according to the application is not limited to the specified application areas.

[0023] If the amplitude rod body is constructed rotationally symmetrical, in particular circular, it usually has a diameter of less than a quarter of the longitudinal wavelength, i.e. usually less than 60 mm, preferably less than 50 mm and particularly preferably about 25 mm to 35 mm at a frequency of 20 kHz (kiloHertz). It has proved to be particularly stable vibration behavior using such a relatively small diameter. The ultrasonic vibrations are usually introduced at a frequency of 15 kHz to 50 kHz, preferably 20 kHz to 35 kHz.

[0024] The conversion structure is preferably constructed in the form of material recesses to the outer surface of the amplitude rod body. The material recesses can extend along a helical line. In particular, the material recesses can be constructed in the form of conversion slots. The number of conversion slots can be in the range between 3 and 12, and preferably 6. However, it is also conceivable to provide material recesses in the form of individual holes on the helical line.

[0025] The helical line can be arranged with constant spacing or with variable spacing. In the case of variable spacing, the material recesses are arranged along a curve having a curvature on the outer surface of the amplitude rod body. The helical line preferably has an included angle of about 45° with respect to the longitudinal axis of the amplitude rod body.

[0026] Usually, the conversion structure and the damping structure are constructed as separate structures from one another. However, it is also conceivable to provide a structure which is continuous along the axis, which in a first portion is a conversion structure and in a second portion is a damping structure. In particular in the case where the conversion structure extends with variable spacing along a curve, it is conceivable that the spacing is reduced to such an extent that the structure ends in a region extending approximately perpendicular to the axis and forms a damping structure in this region.

[0027] While a damping structure extending in a plane perpendicular to the axis is particularly advantageous, it is not excluded that the damping structure does not extend completely perpendicular to the axis. Usually, the damping structure can extend at an angle of between 85° and 95° with respect to the axis. While a damping structure with constant spacing is advantageous, a damping structure with variable spacing is also feasible.

[0028] As an alternative to material recesses, it is also conceivable to construct the conversion structure in the form of material deposits on the outer and / or inner surfaces of the amplitude rod body. In particular, such material deposits can be set in the amplitude rod body processed by additive manufacturing processes. This is especially advantageous for applications with high hygiene requirements. For example, in packaging applications, such material deposits, rather than openings, can effectively reduce bacterial deposition or the passage of bacteria or dirt.

[0029] In the case of a hollow body, the material recess can extend through the entire wall of the luffing rod body. However, it is also conceivable to set the material recess as a groove only on the outer surface of the luffing rod body, especially in the case of a luffing rod body constructed as a non-hollow body. Furthermore, conversion structures with a combination of material recesses and material accumulation, or combinations of the above-mentioned different forms of material recesses, are also conceivable.

[0030] The damping structure is typically formed by a material weakening section within the amplitude transformer body. This weakening section is preferably in the form of damping slots. The damping slots extend particularly along a direction perpendicular to the longitudinal axis of the amplitude transformer body. Due to the damping slots, the ultrasonic inlet side is connected to the coupling end only through webs arranged between the damping slots. These webs are stable and transmit torsional vibrations. Simultaneously, due to the reduction or absence of material in the region of the damping slots, longitudinal vibrations are significantly prevented from being transmitted from the ultrasonic inlet side to the coupling side. The damping structure filters longitudinal vibrations, thus transmitting only vibrations with torsional components. Multiple rows of damping slots are also conceivable. The number of damping slots is 3 to 12, preferably 6.

[0031] Of course, other types of damping can also be envisioned. Besides damping slots, other types of material weakening sections can be envisioned, for example, by reducing the elastic modulus involved in longitudinal deformation through material processing. It is also conceivable to construct damping structures by incorporating additional materials.

[0032] The conversion structure typically extends along the longitudinal length of the ultrasonic component, extending for approximately 10% to 30%, preferably approximately 15% to 25% of the amplitude transformer body length. This length has proven to provide a particularly favorable conversion effect from longitudinal to transverse vibration.

[0033] Furthermore, from a longitudinal perspective, the conversion structure is preferably arranged eccentrically between the damping structure and the first end face, closer to the first end face.

[0034] An intermediate region is formed between the conversion structure and the damping structure. When viewed longitudinally, the ratio of longitudinal vibration to torsional vibration changes continuously within this intermediate region.

[0035] Consequently, the ratio between the longitudinal vibration component and the torsional vibration component changes along the longitudinal axis. The damping structure is preferably positioned in the region where the torsional vibration amplitude is largest or the torsional vibration proportion is largest.

[0036] The length of the intermediate region is preferably selected to minimize the proportion of torsional vibration in the intermediate region of the damping structure. This results in particularly stable amplitude and low-frequency fluctuations.

[0037] In a preferred embodiment, a groove is further provided in the first end face of the ultrasonic inlet side. The groove is provided with a coupling surface for connecting the amplitude transformer body and the vibration surface of the ultrasonic transducer. This prior art method allows for optimized coupling of longitudinal vibration. In particular, the structure in pending application EP 3663008, the contents of which are the subject of this application by cross-reference.

[0038] According to another preferred embodiment, a stop flange for abutting against the ultrasonic induction side of the ultrasonic welding electrode is provided on the outer surface of the amplitude transformer body in the region of the second end face. As described above, the amplitude transformer body may also have threads for connecting the ultrasonic welding electrode. The threads extend from the stop flange on the opposite side of the conversion structure.

[0039] The amplitude transformer body is typically fabricated as a single piece and constructed from materials such as steel, titanium, aluminum, or ceramic. However, it is also conceivable to use a multi-piece amplitude transformer body. In this case, it is particularly conceivable to use an amplitude transformer body composed of multiple components made of different materials. In particular, it is conceivable to incorporate additional damping material in the area of ​​the damping structure between the coupling side and the ultrasonic induction side.

[0040] Particularly preferred is that the conversion structure, damping structure, ultrasonic induction side, amplitude transformer body length, and second end face are matched so that the torsional vibration direction on one side of the damping structure extends in the opposite direction to the torsional vibration on the other side of the damping structure. Appropriate dimensions can be determined, in particular, through finite element calculations. Especially, sufficient rigidity of the web in the damping structure region achieves stable and thus more reliable amplitude and smaller frequency variations.

[0041] The present invention also relates to an apparatus for ultrasonically processing a workpiece. The apparatus has at least one ultrasonic amplitude transformer as described above. An ultrasonic welding electrode is connected, in particular threadedly connected, to the coupling side of the ultrasonic amplitude transformer on the ultrasonic induction side. Preferably, the apparatus also includes a transducer for operating the ultrasonic amplitude transformer, particularly for introducing longitudinal vibrations into the ultrasonic induction side of the ultrasonic amplitude transformer.

[0042] The device also features a receiving section for holding the workpiece to be processed. Furthermore, it provides an actuation device for moving the ultrasonic amplitude transformer and ultrasonic welding electrode toward the receiving section. Thus, the workpiece can be clamped between the working surface of the ultrasonic welding electrode and the receiving section, and processed using ultrasonic technology and methods known in the prior art.

[0043] The ultrasonic welding electrode may also be equipped with a positioning fixture for the workpiece, especially a support for flexible mounting. The positioning fixture is preferably fixed at the minimum value of local torsional vibration of the ultrasonic welding electrode.

[0044] Finally, the present invention relates to a method for ultrasonically machining a workpiece. In particular, an ultrasonic amplitude transformer with the aforementioned ultrasonic welding electrode is used. In a first step, longitudinal vibration is introduced on the acoustic wave guiding side of the amplitude transformer body. The introduced longitudinal vibration is converted into torsional vibration having a vibration component in a plane perpendicular to the vibration direction of the longitudinal vibration by means of a conversion structure.

[0045] These torsional vibrations are introduced into the ultrasonic welding electrode connected to the main body of the amplitude transformer. Preferably, a damping structure, especially a longitudinal damping structure, is used to reduce the longitudinal vibration between the conversion structure and the coupling side. Attached Figure Description

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, the accompanying drawings of which illustrate:

[0047] Figure 1 This is a schematic view of the device according to the present invention;

[0048] Figure 2 This is a perspective view of a first ultrasonic amplitude transformer with an ultrasonic welding electrode according to the present invention;

[0049] Figure 3 This is a perspective view of a second ultrasonic amplitude transformer with an ultrasonic welding electrode according to the present invention;

[0050] Figure 4 It is based on Figure 3 A partially transparent perspective view of the implementation method;

[0051] Figures 5a / b are schematic views of the vibration characteristics of the ultrasonic amplitude transformer according to the present invention;

[0052] Figure 6 It is based on Figure 2 An enlarged view of the damping structure in the embodiment. Detailed Implementation

[0053] Figure 1 The apparatus 2 for processing workpiece W is shown schematically. Two components to be welded together are shown here as workpiece W. The apparatus 2 has a receiving section 41 for receiving workpiece W.

[0054] The ultrasonic amplitude transformer 1 with the amplitude transformer body 10 can be excited to ultrasonic vibration by means of the transducer 40. The transducer 40 generates longitudinal vibration SL in the longitudinal direction under the excitation of the ultrasonic generator 33. In the ultrasonic amplitude transformer 1, the longitudinal vibration SL is coupled into and then converted into torsional vibration ST at the first end face 12, thereby generating torsional vibration ST at the second end face 14 of the coupling side 13 of the amplitude transformer body 10.

[0055] The torsional vibration is transferred to the ultrasonic guide side 31 of the ultrasonic welding electrode 30. The ultrasonic welding electrode 30 is a torsional ultrasonic welding electrode and guides the torsional vibration ST into the workpiece W.

[0056] The transducer 40, ultrasonic amplitude transformer 1, and ultrasonic welding electrode 30 are stacked and mounted in the frame, and can be moved along the axial direction A by means of a drive device, thereby moving the ultrasonic welding electrode 30 and the working surface 32 toward the workpiece W. A pneumatic drive device 42 is typically provided to move this stack along the axial direction A. However, it is also conceivable to utilize a servo pressure device using known existing technologies and methods.

[0057] Figure 2 A perspective view is shown of a first embodiment of the ultrasonic amplitude transformer 1 according to the present invention and an ultrasonic welding electrode 30 applied at a frequency of 35 kHz. The ultrasonic amplitude transformer 1 has a generally cylindrical amplitude transformer body 10. The amplitude transformer body 10 has an ultrasonic induction side 11 with a first end face 12 and a coupling side 13 with a second end face 14. The second end face 14 is formed by means of a stop flange 22.

[0058] The longitudinal vibration SL can be introduced longitudinally into the ultrasonic amplitude transformer 1 at the first end face 12. For this purpose, the amplitude transformer body 10 has a blind hole-shaped groove 20 at the first end face 12. A transducer can be connected using this groove 20, thereby coupling the longitudinal vibration SL into the ultrasonic amplitude transformer 1.

[0059] The ultrasonic amplitude transformer 1 also has a hexagonal profile 28 for the mechanism. This allows the ultrasonic amplitude transformer 1 to be threadedly connected to the ultrasonic welding electrode by means of the mechanism.

[0060] A conversion structure 15 in the form of a conversion slot 16 is provided adjacent to the ultrasound inlet side 11 along the longitudinal direction L. The conversion slot 16 is provided at an angle α relative to the longitudinal axis L on the surface 17 of the amplitude transformer 10. In the illustrated embodiment, the amplitude transformer body 10 is constructed as a hollow body in the region of the transducer structure, and the conversion slot 16 extends through the outer shell of the hollow body.

[0061] However, it is also conceivable to simply provide grooves in surface 17, and / or to construct the amplitude rod body 10 as a solid body.

[0062] The switching slot 16 induces a vibration with a torsional component ST, which is generated by the longitudinal vibration SL guided from the ultrasonic inlet side 11 to the ultrasonic amplitude transformer 1.

[0063] In the intermediate region 9 (located downstream of the conversion structure 15 along the longitudinal direction L), there exists vibration with both longitudinal and torsional vibration components. The ratio of the individual vibration components SL and ST varies along the longitudinal direction L.

[0064] The intermediate region 9 is joined to a damping region 18. The damping region 18 is formed by two rows of damping slots 19 extending circumferentially along the surface 17 of the luffing rod body 10. The slots 19 are regularly arranged circumferentially around the luffing rod body 10 and are separated from each other by longitudinally extending webs 8 (see also...). Figure 6 ).

[0065] Viewed longitudinally, a coupling side 13 with a stop flange 22 is arranged behind the damping structure 18. A web 8 connects the intermediate region 9 and the coupling side 13. The torsional vibration component is transmitted to the coupling side 13 through the web 8, causing the coupling side to vibrate almost exclusively as a torsional vibration ST. The coupling side 13 exhibits almost no longitudinal vibration. The torsional vibration ST travels along a plane E perpendicular to the longitudinal axis L.

[0066] The stop flange 22 has a thread 27 for connection with the ultrasonic welding electrode 30 in the longitudinal direction L.

[0067] The ultrasonic welding electrodes 30 are constructed using known existing techniques and methods. They have internal threads 34 on the ultrasonic inlet side 31 for connection with the external threads 27 of the ultrasonic amplitude transformer 1.

[0068] The dimensions of the amplitude transformer body, and especially the conversion slot 16 and damping slot 19, and their arrangement on the amplitude transformer body 10, are selected to produce particularly stable amplitude and low-frequency fluctuations at a predetermined excitation frequency. The torsional frequency and longitudinal frequency should overlap as much as possible.

[0069] Specifically, the dimensions of the damping slot 19 should be designed and positioned such that the phase reversal of torsional vibration occurs in the middle region of the damping structure 18, i.e., the minimum value of torsional vibration occurs. The dimensions of the amplitude transformer body 10 can typically be set as follows.

[0070] The amplitude transformer body 10 has a length 1 (excluding the protruding thread 27) that depends on the material and frequency. In the embodiment shown here (shown to scale), the length 1 is less than half a longitudinal wavelength.

[0071] Viewed circumferentially, the transition slots 16 do not overlap and preferably extend at a 45° angle. Therefore, depending on the number of transition slots 16, their length k in the longitudinal direction L is approximately in the range of D / 6 to 3D, and approximately D / 2 when there are six transition slots 19, where D is the outer diameter of the amplitude transformer body 10. In the embodiment shown here, the length k is approximately 15% of the total length I of the amplitude transformer body 10. The transition slots 16 extend along a helix at an angle α of approximately 45° about the longitudinal axis L. However, the helix can also have variable spacing, thus making the angle α different at each point of the transition slots 16.

[0072] According to Figure 2 In this implementation, the length of the intermediate region 9 is typically greater than one-quarter of the twist wavelength.

[0073] The length of the damping structure 18 is chosen to provide sufficient elasticity and thus sufficient damping.

[0074] The conversion slot starts from end face 12 at a distance approximately equal to distance k.

[0075] The coupling side 13 without thread 27 is constructed to be shorter, so that the stop flange 2 region has the largest possible torsional amplitude.

[0076] The switching slot 16 typically begins at a distance of about one-eighth of the longitudinal wavelength from the first end face 12.

[0077] Viewed along the longitudinal direction L, the damping slot 19 typically has a height h of 1 mm to 10 mm (see...). Figure 6 Similar dimensions also apply to the following embodiments.

[0078] Figure 3 A perspective view showing a second embodiment of the ultrasonic amplitude transformer 2 and an ultrasonic welding electrode 30 applied at an ultrasonic frequency of 30 kHz is shown. The same reference numerals denote the same parts. (The last sentence appears to be incomplete and possibly refers to a different document.) Figure 2 The implementation method differs, with the amplitude transformer body 10 and ultrasonic welding electrode 30 being longer and thicker. The ultrasonic welding electrode 30 is also provided with an additional vibration block 35 for adapting to the vibration frequency and amplitude.

[0079] according to Figure 2 and Figure 3 The amplitude transformer body 10 is constructed as a hollow body. The amplitude transformer body 10 has a circular cross-section. The cross-section has a variable outer diameter. The outer diameter in the region of the conversion structure 15 is slightly larger than the outer diameter in the intermediate region 9. The stepped portion 21 is used to adjust the elasticity and reduce the stiffness. The conversion slot 16 and the damping slot 19 extend through the entire wall of the hollow cylindrical amplitude transformer body 10.

[0080] According to Figure 2 and Figure 3In this embodiment, six damping slots 19 are arranged when viewed from the circumferential direction. In this embodiment, the length of the damping slots 19 along the circumferential direction is greater than the length of the web 8. The web 8 and the damping slots 19 extend a total angle range of approximately 60°, with the damping slots extending approximately 50° and the web 8 extending approximately 10°. The center of the first row of damping slots 19 is aligned with the center of the transition slot 16 along the longitudinal axis L. The second row of damping slots is offset by 30° relative to the first row of damping slots, so that the web 8 of the first row of damping slots 19 is located at the center of the second row of damping slots 19. Of course, in an alternative embodiment, the above-mentioned center points may also be offset relative to the longitudinal axis L.

[0081] Figure 4 Shown in partially transparent view according to Figure 3 The ultrasonic welding electrode 30 is constructed as a hollow body and has a through hole. Viewed longitudinally L, a threaded hole 36 with a smaller inner diameter abuts an internal thread 34. Adjacent to the inner hole 16, the ultrasonic welding electrode 30 has a bell-shaped groove 37. The threaded hole 36 is arranged to a torsional vibration node. It is used to receive a positioning fixture for the workpiece W to be processed. Such a positioning fixture can be constructed, for example, as shown in DE 10204 212 313 (the contents of which are incorporated herein by cross-reference) and provides flexible mounting for the workpiece.

[0082] Figures 5a and 5b illustrate the vibration characteristics of another embodiment of the ultrasonic welding electrode 30, which is excited to perform torsional vibration ST using the ultrasonic amplitude transformer 1 according to the invention. Figures 2-4 Unlike the embodiment shown, the ultrasonic amplitude transformer 1 presented here has only one row of damping slots 19. Torsional vibration ST has a tangential vibration direction about the longitudinal axis L. The distribution of the longitudinal and torsional components depends on the arrangement and dimensions of the conversion slots 16 and the damping slots 19. The conversion slots 16 and the damping slots 19 are specifically arranged to obtain the most stable vibration characteristics possible. The vibration curve of the amplitude transformer body 10 can be determined using finite element analysis. Figures 5a and 5b show two finite element analyses of the ultrasonic amplitude transformer 1 with maximum torsional amplitude in the region of the second end face 14. The vibration direction at each time point is schematically shown with the aid of arrows.

[0083] Observing along the longitudinal direction L, the vibration in the first part I is mainly longitudinal.

[0084] Due to the transformation structure 15, vibrations with torsional and longitudinal components exist in the second part II (indicated by oblique arrows), where the torsional component increases when viewed from the longitudinal direction L.

[0085] In section III, slightly above the damping structure 18, the dominant component is torsional vibration.

[0086] Due to the specific arrangement of the conversion structure 15 and the damping structure 18, the vibration direction of the torsional vibration is deflected in the region of the damping structure 18. Phase reversal exists in the central region. The torsional vibration in region IV occurs in the opposite direction to the vibration in region III. This achieves a very stable vibration state. In the region of the end face 14 of the ultrasonic amplitude transformer 1, almost only torsional vibration exists, causing the ultrasonic welding electrode to be excited to perform almost pure torsional vibration.

[0087] When the plastic part comes into contact with the working surface 32 Figure 2 The ultrasonic welding electrode shown in Figure 5 is typically used for welding plastic parts. The working surface 32 is constructed in a known prior art and manner, and may, for example, have folds.

[0088] Figure 6 It shows that according to Figure 2 An enlarged view of the damping structure 18 of the embodiment. A radially extending web 8 divides the damping slots 19 into upper and lower rows. The upper row of damping slots 19 is offset by 30° relative to the lower row of damping slots 19. The height h and position of the damping slots 19 are specifically selected to reverse the direction of torsional vibration from the upper region of the upper row of damping slots 19 to the lower region of the lower row of damping slots, particularly the region below the stop flange 22 (schematically shown with arrows).

Claims

1. An ultrasonic amplitude transformer (1) for use as an ultrasonic welding electrode (30) for machining a workpiece (W) by means of ultrasonic vibration, comprising: An amplitude transformer body (10) with a longitudinal axis (L) has an ultrasonic induction side (11) with a first end face (12) and a coupling side (13) with a second end face (14) for connecting an ultrasonic welding electrode (30). In this process, longitudinal vibration (SL) is guided into the amplitude transformer body (10) along a direction parallel to the longitudinal axis (L) on the ultrasonic inlet side (11). in, A conversion structure (15) is arranged between the ultrasound induction side (11) and the coupling side (13), by means of which a torsional vibration (ST) with a vibration component in a plane (E) perpendicular to the longitudinal axis (L) can be generated by longitudinal vibration (SL); The feature is that a damping structure (18) is provided between the conversion structure (15) and the coupling side (13), which reduces the longitudinal vibration (SL) on the coupling side (13). The damping structure (18) is formed by the material weakening part of the amplitude rod body (10), and the material weakening part of the damping structure (18) is formed as a damping slot (19).

2. The ultrasonic amplitude transformer (1) according to claim 1, wherein the amplitude transformer body (10) is wholly or partially constructed as a hollow body.

3. The ultrasonic amplitude transformer (1) according to claim 1 or 2, wherein the ultrasonic amplitude transformer (1) is provided with a connecting part on the coupling side (13) for connecting the ultrasonic welding electrode (30).

4. The ultrasonic amplitude transformer (1) according to claim 1 or 2, wherein the ultrasonic amplitude transformer (1) is provided with a profile (28) suitable for connecting the ultrasonic amplitude transformer (1) to the ultrasonic welding electrode (30).

5. The ultrasonic amplitude transformer (1) according to claim 1 or 2, wherein the amplitude transformer body (10) is configured to be rotationally symmetric.

6. The ultrasonic amplitude transformer (1) according to claim 5, wherein the amplitude transformer body (10) has a circular cross-section.

7. The ultrasonic amplitude transformer (1) according to claim 5, wherein the amplitude transformer body (10) has an outer diameter less than one-quarter of the longitudinal wavelength.

8. The ultrasonic amplitude transformer (1) according to claim 1 or 2, wherein the conversion structure (15) is formed as a material recess (16) on the outer surface (17) of the amplitude transformer body (10), the material recess (16) extending spirally.

9. The ultrasonic amplitude transformer (1) according to claim 8, wherein the spiral has an angle of 45° relative to the longitudinal axis (L) in a manner that converts the slot.

10. The ultrasonic amplitude transformer (1) according to claim 1, wherein the damping slot (19) extends in a direction perpendicular to the longitudinal axis (L).

11. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein the damping structure (18) is arranged adjacent to the region that occupies the largest proportion of torsional vibration (ST).

12. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein the conversion structure (15) extends over 10% to 30% of the length (l) of the amplitude transformer body (10).

13. The ultrasonic amplitude transformer (1) according to claim 12, wherein the conversion structure (15) extends over 10% to 20% of the length (l) of the amplitude transformer body (10).

14. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein, viewed along the longitudinal direction (L), the conversion structure (15) is eccentrically arranged between the damping structure (18) and the first end face (12).

15. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein a groove (20) with a coupling surface is provided on the ultrasonic inlet side (11) for connecting with the vibration surface of the ultrasonic transducer (40).

16. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein in the region of the second end face (14), a stop flange (22) is provided on the outer surface (17) of the amplitude transformer body (10) for abutting against the ultrasonic guide surface (31) of the ultrasonic welding electrode (30).

17. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein the amplitude transformer body (10) is constructed as a single piece.

18. The ultrasonic amplitude transformer (1) according to any one of claims 1, 2 and 10, wherein the length of the conversion structure (15), the damping structure (18), the ultrasonic induction side (11), the amplitude transformer body (10) and the second end face (14) are constructed and adapted to each other such that the vibration direction of the torsional vibration on one side of the damping structure (18) extends in the opposite direction to the torsional vibration on the other side of the damping structure (18).

19. An apparatus (2) for ultrasonically processing a workpiece (W), having an ultrasonic amplitude transformer (1) according to any one of claims 1 to 18 and having an ultrasonic welding electrode (30), wherein the ultrasonic welding electrode (30) is connected to the coupling side (13) of the ultrasonic amplitude transformer (1) on its ultrasonic induction side (31), wherein the ultrasonic welding electrode (30) has a positioning fixture for the workpiece.

20. The device (2) according to claim 19, wherein the ultrasonic welding electrode (30) has a resiliently mounted clamp.

21. The device (2) according to claim 19, wherein the positioning fixture is located at the minimum local torsional vibration of the ultrasonic welding electrode (30).

22. The device (2) according to any one of claims 19 to 21, wherein the device is further provided with a transducer (40) for guiding longitudinal vibration (SL) into the ultrasonic induction side (11), a receiving part (41) for the workpiece (W) to be processed, and a driving device (42) for moving the ultrasonic component (1) to the receiving part (41).

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