ULTRASONIC WELDING SYSTEM WITH SUPPORT ELEMENT

Abstract

The present invention concerns an ultrasonic welding installation comprising an ultrasonic vibration unit having a sonotrode and a converter, wherein the sonotrode and the converter are arranged in mutually adjacent relationship along a longitudinal axis and the ultrasonic vibration unit can be caused to resonate with an ultrasonic vibration in the direction of the longitudinal axis with a wavelength λ. To provide an ultrasonic welding installation which allows simple and fast highly precise adjustment of the sealing surfaces of the sonotrode relative to the anvil according to the invention there is proposed a support element for supporting a force applied to the sonotrode perpendicularly to the longitudinal axis, wherein the sonotrode and the support element have mutually corresponding support surfaces which at least when a force is applied to the sonotrode perpendicularly to the longitudinal axis come into contact with each other, wherein the support surfaces are of such a configuration that when they are in contact with each other they prevent a relative movement of the sonotrode with respect to the support element in the direction of the longitudinal axis and do not impede a rotation of the sonotrode about the longitudinal axis.

Claims

1. An ultrasonic welding installation comprising an ultrasonic vibration unit having a sonotrode (1) and a converter, (3), wherein the sonotrode (1) and the converter (3) are arranged in mutually adjacent relationship along a longitudinal axis and the ultrasonic vibration unit can be caused to resonate with an ultrasonic vibration in the direction of the longitudinal axis with a wavelength λ, characterised in that there is provided a support element (7) for supporting a force applied to the sonotrode (1) perpendicularly to the longitudinal axis, wherein the sonotrode (1) and the support element (7) have mutually corresponding support surfaces which at least when a force is applied to the sonotrode (1) perpendicularly to the longitudinal axis come into contact with each other, wherein the support surfaces are of such a configuration that when they are in contact with each other they prevent a relative movement of the sonotrode (1) with respect to the support element (7) in the direction of the longitudinal axis and do not impede a rotation of the sonotrode (1) about the longitudinal axis.

2. An ultrasonic welding installation according to claim 1 characterised in that either the sonotrode (1) has a rib (6) and the support element (7) has a groove (30) or the sonotrode (1) has a groove and the support element (7) has a rib (6), wherein the rib (6) and the groove (30) have the corresponding support surfaces.

3. An ultrasonic welding installation according to claim 1 characterised in that there is provided a counterpart tool, wherein the sonotrode (1) and the counterpart tool are moveable relative to each other in a direction perpendicular to the longitudinal axis and the support element (7) is so positioned that a force exerted on the sonotrode (1) by the counterpart tool is transmitted to the support element (7).

4. An ultrasonic welding installation according to claim 2 characterised in that the rib (6) and the groove (30) are of a trapezoidal cross-section, wherein preferably the rib (6) and the groove (30) respectively have two support surfaces which do not extend parallel and which include with the longitudinal axis an angle which is less than 90°.

5. An ultrasonic welding installation according to claim 1 characterised in that the support element (7) is of such a configuration that it is reciprocable between two positions perpendicularly to the longitudinal axis.

6. An ultrasonic welding installation according to claim 1 characterised in that there is provided a holder (5) for holding the ultrasonic vibration unit.

7. An ultrasonic welding installation according to claim 6 characterised in that the holder (5) has an angle positioning device, wherein the angle positioning device and the ultrasonic vibration unit are of such a configuration that they can be connected together in positively locking relationship so that a rotation of the ultrasonic vibration unit about the longitudinal axis is prevented by the positively locking connection and a relative movement between the ultrasonic vibration unit and the holder (5) in the direction of the longitudinal axis is not prevented.

8. An ultrasonic welding installation according to claim 7 characterised in that the ultrasonic vibration unit has an outer bead with at least one recess (21), wherein the angle positioning device has at least one projection (20) which corresponds to the recess (21) and which can engage into the recess (21) and thus provides the positively locking connection.

9. An ultrasonic welding installation according to claim 8 characterised in that the outer bead has a plurality of recesses (21).

10. An ultrasonic welding installation according to claim 7 characterised in that the at least one recess of the outer bead and the projection (20) of the angle positioning device have mutually corresponding contact surfaces which when the ultrasonic vibration unit is fitted into the angle positioning device come into contact with each other upon rotation of the ultrasonic vibration unit about the longitudinal axis.

11. An ultrasonic welding installation according to claim 7 characterised in that the angle positioning device has a fixing element (9) for fixing the angle positioning device to a machine stand and has a coupling element (8) which is reciprocable between two positions in the direction of the longitudinal axis relative to the fixing element (9), wherein the positively locking connection can be produced between the coupling element (8) and the ultrasonic vibration unit.

12. An ultrasonic welding installation according to claim 7 characterised in that the outer bead is arranged on the sonotrode (1) or an amplitude transformer (4) arranged between the sonotrode (1) and the converter (3).

13. An ultrasonic welding installation according to claim 1 characterised in that there is provided an amplitude transformer (4) arranged between the sonotrode (1) and the converter, (3), wherein the amplitude transformer (4) is connected to the converter (3) and/or the sonotrode (1) by way of a positively locking connection which provides a positively locking relationship in all directions of the plane perpendicular to the longitudinal axis.

14. An ultrasonic welding installation according to claim 13 characterised in that the positively locking connection between the amplitude transformer (4) and the converter (3) or between the amplitude transformer (4) and the sonotrode (1) comprises a pin (22) and a corresponding opening (26).

15. An ultrasonic welding installation according to claim 14 characterised in that the pin (22) and the corresponding opening (26) are not of a rotationally symmetrical configuration with respect to the longitudinal axis.

16. An ultrasonic welding installation according to claim 14 characterised in that the pin (22) and the corresponding opening (26) are of a conical configuration or have a conical portion.

17. An ultrasonic welding installation according to claim 1 characterised in that the holder (5) has a clamping device which is reciprocable between an opened position in which the ultrasonic vibration unit can be removed from the holder (5) and a closed position in which the clamping device comes into contact with the ultrasonic vibration unit at least two holding points and exerts a force on same so that the ultrasonic vibration unit is held.

18. An ultrasonic welding installation according to claim 17 characterised in that the holding points are arranged on the outer bead.

19. An ultrasonic welding installation according to claim 2 wherein the rib (6) or the groove (30) of the sonotrode (1) are arranged at a vibration node of the resonance vibration of the wavelength λ.

20. An ultrasonic welding installation according to claim 5 wherein there is provided a locking device with which the support element (7) can be locked in at least one position.

Description

[0043] Further advantages, features and possible uses of the present invention will be apparent from the description hereinafter of a preferred embodiment of the invention and the associated Figures in which:

[0044] FIG. 1 shows a plan view of an ultrasonic welding installation according to the invention,

[0045] FIG. 2 shows a perspective view of the ultrasonic welding installation of FIG. 1 without a holder,

[0046] FIG. 3 shows a perspective view of the holder of FIG. 1 without the vibration structure,

[0047] FIGS. 4a, 4b, c show a perspective view of the coupling element of the angle positioning element of FIG. 1 and a sectional view of the angle positioning element and the holder,

[0048] FIG. 5 shows a sectional view through the FIG. 1 embodiment,

[0049] FIG. 6 shows a perspective view of the amplitude transformer of FIG. 1, and

[0050] FIG. 7 shows a perspective view of the sonotrode of FIG. 1.

[0051] FIG. 1 shows a first embodiment of the ultrasonic welding installation according to the invention. This ultrasonic welding installation is intended specifically for welding metal. It has an ultrasonic vibration unit including a sonotrode 1, an amplitude transformer 4 and a converter 3. The elements of the ultrasonic vibration unit are arranged in mutually juxtaposed relationship along a longitudinal axis. The converter 3 converts an electrical ac voltage into a mechanical ultrasonic vibration. That mechanical vibration is changed in its amplitude but not in its frequency by means of the amplitude transformer 4 and transmitted to the sonotrode 1. On the side of the sonotrode 1, opposite the converter 3, it has altogether four sealing surfaces 2 provided to come into contact with the material to be processed. The ultrasonic vibration unit with its individual elements, that is to say the converter 3, the amplitude transformer 4 and the sonotrode 1, are matched to each other in such a way that they can be set in resonance with an ultrasonic frequency of the wavelength. Within the sonotrode a standing longitudinal half-wave is then formed. The ultrasonic vibration unit has to be held in a machine support stand. The holder 5 is provided for that purpose, being described in detail hereinafter.

[0052] FIG. 2 shows a perspective view of the FIG. 1 embodiment. It will be seen here that the individual parts of the ultrasonic vibration unit, namely the converter 3, the amplitude transformer 4 and the sonotrode 1 are substantially rotationally symmetrical, wherein only the end of the sonotrode 1, that is remote from the converter 3, is of a square configuration with a welding surface 2 provided at each edge surface of the square cross-section. Alternatively the sonotrode could also be of other cross-sections like for example triangular, rectangular but not square, and so forth.

[0053] Particularly when welding metals and more specifically in particular non-ferrous metals like for example copper or aluminium by means of ultrasound the welding surface suffers from considerable wear so that the ultrasonic welding installation has to be partially or completely replaced at regular intervals.

[0054] As the illustrated sonotrode has a total of four sealing surfaces 2 it can be turned through 90° when a sealing surface 2 is worn and continue to be used in that position.

[0055] For processing metal by means of ultrasound the material to be processed is arranged between the sealing surface 2 of the sonotrode 1 and a counterpart tool (not shown) and then the ultrasonic vibration unit is caused to vibrate so that an ultrasonic vibration can be transmitted into the material to be processed by way of the sealing surfaces 2.

[0056] The holder 5 in FIG. 1 is shown separately in FIG. 3. It is in the form of a tightening clamping sleeve. It can be seen that the holder completely encloses the amplitude transformer. It does however have a slot 11 formed by two limb elements 12, 13 of the holder. In the position shown in FIG. 3 the amplitude transformer 4 can be pushed axially into the holder 5. In that position the amplitude transformer 4 and therewith the entire ultrasonic vibration unit can be rotated within the holder 5 about its longitudinal axis. As soon as the desired position of the ultrasonic vibration unit or the sealing surfaces 2 of the sonotrode 1 is reached the two limb elements 12, 13 can be moved towards each other by means of screws which are accommodated in the bores 14 provided within the limb element 13 in the form of a threaded bore and within the limb element 12 in the form of a through bore so that the inside diameter of the sleeve-like holder 5 is reduced and the amplitude transformer 4 is clamped fast in the holder 5 and relative rotation of the ultrasonic vibration unit about its longitudinal axis with respect to the holder 5 is then no longer possible. In that respect it is to be noted that in the opened state of the holder the bore should be only minimally larger than the outside diameter of the amplitude transformer to be clamped. That oversize should be less than 0.1 mm, preferably less than 0.05 mm, and best less than 0.02 mm. In the illustrated embodiment the limb elements 12, 13 have corresponding slot walls which serve as abutment surfaces. That means that the portion of the outer surface of the ultrasonic vibration unit and the inner surface of the tightening sleeve are such that the limb elements 12, 13 can be moved towards each other by means of screws which engage into the bores 14 until the abutment surfaces are in contact with each other and in that situation the ultrasonic vibration unit is held fixedly within the tightening sleeve. That configuration ensures that the tightening sleeve cannot exert an excessively great pressure on the delicate ultrasonic vibration unit. It is therefore not possible for higher forces to be exerted on the ultrasonic vibration unit than that which the sleeve applies to the ultrasonic vibration unit at the time at which the two slot walls of the limb elements 12, 13 meet.

[0057] Preferably the tightening sleeve is of such a design that, with the ultrasonic vibration unit accommoded in the sleeve, a torque of at least 100 Nm, preferably at least 200 Nm and best at least 300 Nm can be applied to the ultrasonic vibration unit without the ultrasonic vibration unit rotating about the longitudinal axis relative to the tightening sleeve within the sleeve. That ensures that individual components like for example the sonotrode can be dismantled from the ultrasonic vibration unit while it is held in the holder.

[0058] On the other hand the clamping force which the holder exerts on the amplitude transformer should be as low as possible to minimise the effects of the clamping action on the amplitude transformer. Therefore the tightening sleeve should be designed in such a way that, if a torque of more than 2000 Nm, preferably more than 1000 Nm and best more than 500 Nm is applied to the ultrasonic vibration unit the unit rotates within the holder about the longitudinal axis relative to the holder. That ensures that the force applied to the amplitude transformer by the holder scarcely influences the vibration.

[0059] FIG. 4a shows a perspective view of the coupling element 8 of the angle positioning device. The angle positioning device serves to set the angular position of the sealing surfaces 2 of the sonotrode as precisely as possible in a simple fashion.

[0060] The angle positioning device has the coupling element 8 which is in the form of a sleeve.

[0061] At its side remote from the converter there is a row of projections 27 and recesses 28. In that case the outside diameter of the converter housing is less than the inside diameter of the coupling element so that the ultrasonic vibration unit including the converter can be displaced by the coupling element until the recesses and projections engage into each other.

[0062] As can be seen in particular from FIG. 5 the amplitude transformer has an outer bead which here is formed by a leg 15 and a flange having a first and a second sleeve portion 16, 17. The leg 15 is connected to the amplitude transformer 4 at a vibration node. From the amplitude transformer 4 at the end of the leg 5 the first sleeve portion 16 extends in the direction of the converter 3 and the second sleeve portion 17 extends in the direction of the sonotrode 1. Both the first sleeve portion 16 and also the second sleeve portion 17 have a peripheral collar 18 serving as contact surfaces for the holder 5. That kind of fixing allows a holding action without involving noteworthy influence on the vibration behaviour of the ultrasonic vibration unit.

[0063] FIG. 6 shows a perspective view of the amplitude transformer 4. The two peripheral collars 18 can be seen there. The first sleeve portion 16 has a row of projections 20 and recesses 21 which correspond to the projections 27 and the recesses 28 of the angle positioning device. The projections 27 and the recesses 28 of the angle positioning device can thus be connected to the recesses 21 and the projections 20. That positively locking connection prevents rotation of the ultrasonic vibration unit about the longitudinal axis while a relative movement between the ultrasonic vibration unit and the angle positioning device in the direction of the longitudinal axis is not prevented. In that arrangement the outside diameter of the peripheral collar is somewhat smaller than the inside diameter of the holder.

[0064] FIG. 4b shows the entire rotary positioning device. The coupling element 8 already shown in FIG. 4a bears against a pressure plate 31 which in turn is arranged resiliently on the fixing element 9 by means of the springs 10. The fixing element 9 is arranged stationarily. By virtue of the springs 10 the pressure plate can be moved in the axial direction relative to the fixing element 9. As the coupling element 8 bears against the pressure plate 31 the coupling element moves in the axial direction together with the pressure plate 31. The coupling element can be rotated to and fro relative to the pressure plate 31 between two positions about the longitudinal axis, as is described hereinafter.

[0065] FIG. 4c shows a sectional view of the holder 5 together with the rotary positioning device.

[0066] As also shown in FIG. 2 spring elements 10 press the coupling element 8 forwardly, that is to say in the direction of the sonotrode 1, and thus into engagement with the projections 20 and recesses 21 of the amplitude transformer 4.

[0067] As long as the holder 5 is not yet in its clamped position the ultrasonic vibration unit can be rotated about its longitudinal axis, by the coupling element 8 being urged rearwardly, that is to say in the direction of the converter 3, by means of the ultrasonic vibration unit, against the force of the springs 10. The ultrasonic vibration unit can then be rotated about its longitudinal axis until the projections 20 come to lie in the recesses 28. The coupling element 8 therefore latches into the flange of the amplitude transformer 4.

[0068] In the illustrated embodiment the number of projections 20 and 27 and the number of recesses 21 and 28 corresponds to the number of sealing surfaces 2 on the sonotrode 1. This therefore ensures that the ultrasonic vibration unit can only be fitted in selected angle positions.

[0069] In the illustrated embodiment a small relative rotation of the coupling element 8 is additionally possible relative to the fixing element 9 about the longitudinal axis. To implement such a slight rotary movement there is provided an adjusting element which is in the form of an eye 19 and is releasably connected to the coupling element 8. A fine adjustment device 29 in the form of a screw connects the adjusting element to the holder 5. Therefore by rotating the screw 29 the coupling element 8 connected to the adjusting element can be rotated to a certain extent with respect to the holder 5 and the fixing element 19 to effect fine adjustment of the angle position. Therefore the screw 29 has some play within the slot provided in the eye 19, both in the axial direction and also in the radial direction.

[0070] FIG. 4d shows a further perspective sectional view through the angle positioning device. The eye 19 has a threaded bore into which a grub screw 32 engages. The eye 19 can be clamped to the coupling element 8 by means of the grub screw 32 so that the coupling element 8 and the eye 19 can only be jointly rotated about the longitudinal axis.

[0071] In the first adjustment of an ultrasonic vibration unit within the holder or if the angular position of the sealing surfaces with respect to the projections 20 and recesses 21 is not known the grub screw 32 can thus be released and the ultrasonic vibration unit fitted into the holder so that the coupling element is pressed against the force of the springs 10 in the direction of the fixing element 9 and then rotated about its longitudinal axis until the projections 20 and recesses 21 of the ultrasonic vibration unit come to lie in the corresponding projections 27 and recesses 28 of the coupling element 8. In that position the coupling element 8 is urged away from the fixing element 9 again by virtue of the force of the springs 10. The ultrasonic vibration unit can now be rotated about its longitudinal axis until the sealing surfaces 2 are approximately in the desired rotary position. As the grub screw 32 is released the coupling element 8 rotates with the ultrasonic vibration unit while the pressure plate 31 remains in its position.

[0072] As soon as the desired rotary position of the ultrasonic vibration unit is approximately reached the grub screw 32 can be tightened to connect the eye 19 to the coupling element 8. Further rotation of the ultrasonic vibration unit about its longitudinal axis is now only still very limitedly possible by rotation of the screw 29.

[0073] As can be seen in FIG. 6 the amplitude transformer has a pin 22 at its side towards the sonotrode 1. FIG. 7 shows a perspective view of the sonotrode 1. At its side towards the amplitude transformer 4 the sonotrode 1 has an opening 26 corresponding to the pin 22. The pin 22 has cut-outs 23 which can also be seen in the corresponding opening 26. When the pin 22 is fitted into the opening 26 that provides a positively locking connection between the sonotrode 1 and the amplitude transformer 4 in terms of a direction of rotation about the longitudinal axis.

[0074] The sonotrode 1 has a central bore 25 which is in the form of a stepped bore and through which a screw can be passed into a corresponding central threaded bore 24 in the amplitude transformer to fix the sonotrode 1 to the amplitude transformer 4.

[0075] As can be seen from the sectional view in FIG. 5 the sonotrode 1 has an outer rib 6 which is arranged at a vibration node of the resonance frequency of the sonotrode 1. The outer rib is of a peripherally extending configuration in the illustrated embodiment. Fixed to the holder 5 is a support element which is moveable in the radial direction between an outer position in which the ultrasonic vibration unit can be received in the holder and an inner position in which the support element prevents a movement of the ultrasonic vibration unit in the direction of the longitudinal axis. The support element can be arrested in that position to prevent unwanted movement of the support element 7 in the direction of the outer position. The support element 7 has a groove 30 in which the outer rib 6 comes to lie. If now a force is exerted on the sonotrode from above as in FIG. 5 by the material to be processed that force is carried by the support element 7. The provided enclosing holder 5 on the amplitude transformer 4 is relatively far away from the machining location, that is to say the sealing surfaces 4, so that already slight welding forces on the sealing surface 2 would result in flexing of the ultrasonic vibration unit. The support device 7 is provided for that purpose.

[0076] To accommodate the ultrasonic vibration unit in the holder firstly the clamping action by means of the screws in the bores 14 has to be released. In addition the support element 7 has to be displaced radially outwardly. The ultrasonic vibration unit can now be fitted into the holder 5. In that case the coupling element 8 and the pressure plate 31 are urged in the direction of the fixing element 9 against the force of the springs 10 until the outer rib 6 comes to lie in the groove 30 in the support element 7 after it has been moved radially inwardly and arrested. That establishes the axial position of the ultrasonic vibration unit. Angle positioning is then effected by the ultrasonic vibration unit being rotated about its longitudinal axis until the projections of the coupling element 8 latch into the corresponding openings on the first sleeve portion 16. The angle position is then also nearly perfectly oriented in that position. Fine adjustment is effected by means of the fine adjustment device, that is to say the eye 19 and the screws 29, by means of which fine adjustment of the angular position can be effected.

[0077] As soon as the correct position of the ultrasonic vibration unit is reached the limb elements 12 and 13 can be moved towards each other by means of the fixing screws which engage into the bores 14 in order to reduce the slot 11 and clampingly embrace the ultrasonic vibration unit in the holding sleeve.

List of References

[0078] 1 sonotrode

[0079] 2 sealing surface

[0080] 3 converter

[0081] 4 amplitude transformer

[0082] 5 holder

[0083] 6 outer rib

[0084] 7 support element

[0085] 8 coupling element

[0086] 9 fixing element

[0087] 10 springs

[0088] 11 slot

[0089] 12 limb element

[0090] 13 limb element

[0091] 14 bore

[0092] 15 leg

[0093] 16 first sleeve portion

[0094] 17 second sleeve portion

[0095] 18 collar

[0096] 19 eye

[0097] 20 projection

[0098] 21 recess

[0099] 22 pin

[0100] 23 cut-out

[0101] 24 central bore

[0102] 25 central bore

[0103] 26 opening

[0104] 27 projection

[0105] 28 recess

[0106] 29 screw

[0107] 30 groove

[0108] 31 pressure plate

[0109] 32 grub screw

[0110] 33 slot wall

[0111] 34 slot wall