CONVERTER WITH AN INTEGRATED BOLT

Abstract

A converter having a converter base part, a bolt connected to the converter base part, a tensioning element and at least one piezo element with a through-opening, the bolt penetrating the through-opening and the tensioning element tensioning the at least one piezo element in the direction of the converter base part, wherein that the bolt is connected to the converter base part in a material bond.

Claims

1.-11. (canceled)

12. A converter comprising: a converter base, a bolt connected to the converter base, a tensioning element, and at least one piezo element with a through-opening, wherein the bolt penetrates the through-opening and the tensioning element tensioning the at least one piezo element in a direction of the converter base in a material bond, wherein the converter is designed as a sonotrode and the converter base has a welding surface which is configured to come into contact with a material to be processed, and wherein the bolt is connected to the converter base in a material bond at a connection point with a transition radius R which is >0.5 mm.

13. The converter according to claim 12, where bolt and the converter base are manufactured from one piece of material.

14. The converter according to claim 12, wherein the transition radius >1 mm.

15. The converter according to claim 12, further comprising: a spacer disc with a through-opening, the spacer disc and the at least one piezo element being arranged in such a way that the bolt first penetrates the through-opening of the spacer disc and then the through-opening of the at least one piezo element, so that the spacer disc abuts both the converter base and the at least one piezo element.

16. The converter according to claim 15, wherein the through-opening of the spacer disc widens on a side facing the converter base, and wherein the through-opening of the spacer disc has, in a sectional view parallel to a longitudinal direction along a length I, an entry radius E on a side facing the converter base which is >0.5 mm.

17. The converter according to claim 16, wherein 2 R>E?R is true.

18. The converter according to claim 16, wherein 1.2 R>E>R is true.

19. The converter according to claim 12, wherein the bolt has an end portion facing away from the converter base and having with an external thread.

20. The converter according to claim 19, wherein the external thread comprises a saw thread.

21. The converter according to claim 12, wherein the converter base has a rear side arranged opposite the welding surface and a recess formed in the rear side in which the bolt is arranged.

22. The converter according to claim 12, wherein the converter has a length I from the welding surface to the rear side, the bolt extending in a direction of the length I.

23. The converter according to claim 22, wherein the length I corresponds to half a wavelength of an ultrasonic oscillation with which the converter is brought into a resonant oscillation.

24. The converter according to claim 22, wherein the at least one piezo element is arranged in a longitudinal direction within the length I.

25. The converter according to claim 24, further comprising: at least four piezo elements each with a through-opening penetrated by the bolt and which are all arranged in the longitudinal direction within the length I.

26. The converter according to claim 12, wherein the transition radius >2 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further advantages, features and possible applications of the present invention will become clear from the following description of a preferred embodiment and the accompanying figures. It shows:

[0034] FIG. 1 a perspective view of a converter according to the invention,

[0035] FIG. 2 a sectional view through the embodiment of FIG. 1,

[0036] FIG. 3 a partially cut side view of the embodiment of FIG. 1, and

[0037] FIG. 4 a sectional view through the embodiment of FIG. 1 without piezo elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] FIG. 1 shows a perspective view of a converter according to the invention. The converter 1 is designed as a sonotrode and has a welding surface 2. The welding surface 2 is intended to come into contact with a material to be machined and to transmit an ultrasonic vibration into the material.

[0039] The converter 1 has a converter base part 3, which has a rear section 10 with a rear side arranged opposite the welding surface 2, and a front section 11, as can be clearly seen in the cross-sectional view of FIG. 2. Here, a circumferential collar 15 forms the boundary between the front section 11 and the rear section 10. During vibration, a standing wave is formed longitudinally along the length I in the converter. The circumferential collar is located in the vicinity of a vibration minimum. The converter can be held on the circumferential collar, e.g. via O-rings, without significantly influencing the vibration behavior of the converter.

[0040] The front section 11, which has the welding surface 2, is for the most part much narrower than the rear section 10. This results in an amplitude transformation in this section. In the rear section 10, a recess is made in the converter base part in which a bolt 4 is integrally connected to the converter base part 3.

[0041] FIG. 3 shows a partially cut side view of the converter 1.

[0042] The converter base part 3 has a length I which is composed of the length of the rear section 10 and the length of the front section 11 of the converter base part 3. The length I thus defines the distance between the welding surface 2 and the rear side of the converter base part. In use, a standing wave with a wavelength corresponding to twice the length I is formed in the converter.

[0043] In the front section 11 of the converter base part 3 there is also a slit 9 which does not extend to the welding surface 2. The slit 9 is arranged on the axis of the bolt 4 in order to improve the vibration behavior of the converter base part 3, which is designed as a sonotrode. A spacer disc 7 with a corresponding central opening is initially pushed over the bolt 4. The spacer disc 7, which like the converter base part 3 including the bolt 4 can be made of titanium, serves to absorb any unevenness on the surface of the converter base part in the immediate vicinity of the bolt 4. The spacer disc 7, which should rest as flat as possible on the surface of the converter base part 3, can however cope with minor deviations in surface quality without causing damage to the spacer disc 7. Likewise, the spacer disc distributes the force of the bolt evenly over the piezo elements. This prevents the risk of overstressing the piezo elements due to an uneven application of force.

[0044] The upper side of the spacer disc 7, i.e. the side facing away from the surface of the converter base part, is preferably provided with a high surface quality. This can be done, for example, by grinding or lapping.

[0045] Several, in the example shown six, piezo elements 6 are applied to the spacer disc 7, which are intended to transmit an electrical AC voltage signal into a mechanical vibration. On the side of the piezo elements 6 facing away from the converter base part 3, a pressure disc 5 is provided, which can be made of steel, for example. The bolt 4 has an external thread at its end section facing away from the converter base part 3, which in the example shown is designed as a saw thread in which a nut 8 engages. By tightening the nut 8, a force is exerted on the pressure disc 5 and via the pressure disc 5 on the piezo elements 6, which in turn transmit the vibration via the spacer element 7 to the converter base part 3, which is designed as a sonotrode.

[0046] It can be seen that the piezo elements 6, the spacer disc 7 as well as the pressure disc 5 have an inner diameter which is slightly larger than the outer diameter of the bolt 4, so that they can expand or contract in the axial direction, i.e. in the direction of the length I, without this having any effect on the bolt 4. The piezo elements can therefore perform an acoustic vibration without being affected by the bolt 4. Furthermore, care must be taken to ensure that the not inconsiderable electrical voltages applied to the piezo elements are not dissipated via the bolt. For this reason too, there must be a sufficiently large distance between the outer diameter of the bolt 4 and the inner diameter of the piezo elements 6.

[0047] FIG. 4 shows a partially cut side view of the converter 1. Here, the piezo elements 6 shown in FIGS. 1-3 as well as the spacer disc 7, the pressure element 5 and the nut 8 have been removed.

[0048] It can be clearly seen in this figure that the bolt has a transition radius 12, which in the example shown, is 0.75 mm. At its end facing away from the converter base part, the bolt has a threaded section 14 onto which the nut 8 can be screwed in order to press the piezo elements 6 together with pressure element 5 and spacer element 7 against the converter base part 3. The described one-piece design of bolt 4 of the converter and converter base part 3 can significantly improve the operating time of the ultrasonic vibration unit. The bolt is required to hold the nut 8, with which the necessary force is applied to the piezo elements in order to press them against the converter base part (or against the spacer disc).

[0049] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE SIGNS

[0050] 1 Converter [0051] 2 Welding surface [0052] 3 Converter base part [0053] 4 Bolt [0054] 5 Pressure disc [0055] 6 Piezo element [0056] 7 Spacer disc [0057] 8 Nut [0058] 9 slit [0059] 10 rear section [0060] 11 front section [0061] 12 Transition radius [0062] 14 Threaded section [0063] 15 collar