阅读说明：本技术 声极以及用于影响声极的振动特性的方法 (Sonotrode and method for influencing the vibration behavior of a sonotrode ) 是由 S.米勒 于 2018-07-12 设计创作，主要内容包括：本发明涉及一种超声波焊接装置的声极(218),其带有具有声极头部(220)的声极体(224),声极头部带有在声极头部的纵向上伸延的至少一个工作面(230)用于焊接或者说焊合和/或变形和/或切割至少一个金属焊接件,其中,声极头部沿着工作面具有彼此不同的横截面,使得声极头部的横截面在工作面的在端侧伸延的端部区域中大于在工作面的中间区域中。(The invention relates to a sonotrode (218) of an ultrasonic welding device, comprising a sonotrode body (224) having a sonotrode head (220) with at least one working surface (230) extending in the longitudinal direction of the sonotrode head for welding or welding and/or deforming and/or cutting at least one metal weld, wherein the sonotrode head has cross sections that differ from one another along the working surface such that the cross section of the sonotrode head is greater in the end regions of the working surface extending at the end than in the middle region of the working surface.)

1. Sonotrode (218, 318, 418) of an ultrasonic welding device with a sonotrode body (224, 324) having a sonotrode head (220,320) with at least one working face (230, 232, 330,332) extending in the longitudinal direction of the sonotrode head for welding or welding together and/or deforming and/or cutting at least one metal weld, wherein the sonotrode head (220,320) has mutually different cross sections along the working face (230, 232, 330,332),

it is characterized in that the preparation method is characterized in that,

the sonotrode head (220,320) has a cross section which is greater in an end region (244, 246,344, 346) of the working surface (230, 232, 330,332) which extends at the end than in a middle region of the working surface.

2. The sonotrode of claim 1, characterized in that the cross section of the sonotrode head (220,320) decreases, in particular continuously, from an end region (244, 344) of the working surface (230, 232, 330,332) running at the end side up to a sonotrode-side end region (246, 346).

3. The sonotrode of claim 1, characterized in that the cross section of the sonotrode head (320) initially decreases from the end region (344) of the working surface (330,332) running at the end and then increases to the sonotrode-side end region (346) of the working surface (330, 332).

4. The applicator of claim 3, wherein the cross-section of the applicator head (320) is smallest in a middle region of the working face (330, 332).

5. The sonotrode of at least one of the foregoing claims, characterized in that said sonotrode head (220,320) has working faces (230, 232, 330,332) in a first longitudinal side (226, 228, 326, 328) extending parallel to each other, wherein said first longitudinal side is connected via a second longitudinal side (234, 236, 334, 336) and the variation of the cross section of said sonotrode head (220,320) is achieved by a variation of the orientation of said second longitudinal side.

6. The sonotrode of at least one of the preceding claims, characterized in that said sonotrode head (220,320) is connected to said sonotrode body (224, 324) via a sonotrode neck (222, 322), the cross section of said neck (222, 322) decreasing from said sonotrode head, passing through a line or area of minimum cross section and thereafter increasing again in the direction of said sonotrode body, wherein the cross section of said sonotrode head (220,320) in the end region (242, 342) at the end side of said working face (230, 232, 330,332) is Q2,

in the case of a tapering cross section of the sonotrode starting from an end region (244) on the end side of the working surface to an end region (246) on the sonotrode side, the cross section in the end region on the sonotrode side is Q3 and the smallest cross section of the neck is Q1, or

In the case of a cross-section which first decreases starting from an end region (244) of the running surface running at the end face and which then increases to an end region (346) on the sonotrode side, the cross-section in the end region on the sonotrode side is Q4, the cross-section in the region of the smallest cross-section between the end face and the end region on the sonotrode side is Q5, the cross-section in the end region running at the end face is Q2 and the smallest cross-section of the neck is Q6, wherein,

Q2Q 1 is between 2.0:1 and 1.1:1 and/or

Q2Q 3 is between 2.0:1 and 1.05:1 and/or

Q2Q 5 is between 2.0:1 and 1.05:1 and/or

Q2Q 6 is between 2.0:1 and 1.1:1 and/or

Q4Q 5 is between 2.0:1 and 1.05:1 and/or

Q3Q 1 is between 1.5:1 and 1.1:1 and/or

Q5Q 6 is between 1.5:1 and 1.1:1 and/or

With the secondary conditions that Q1 is less than Q2, Q3 and Q6 are less than Q2, Q4, Q5 and Q3 are less than Q2 and Q5 is less than Q2, Q4,

wherein especially Q2: Q3 is between 1.05:1 and 1.20:1, preferably between 1.05:1 and 1.15:1, especially about 1.1:1, and/or

In particular Q5: Q6 is 1.21:1 to 1.30:1, in particular about 1.26:1, and/or

In particular Q2: Q6 is between 1.40:1 and 1.55:1, in particular about 1.47:1, and/or

In particular Q2: Q5 is between 1.12:1 and 1.20:1, in particular about 1.16:1, and/or

In particular Q2: Q1 is between 1.20:1 and 2.20:1, preferably 1.22:1 and 1.30:1, in particular about 1.26:1, and/or

In particular Q2: Q4 is between 1.1 and 1.04:1, in particular about 1.02: 1.

7. A method for influencing the vibration behavior of a sonotrode head (220,320) of an ultrasonic metal welding device for welding, deforming and/or cutting metal weldments, which sonotrode head vibrates in the longitudinal direction, wherein the sonotrode head is connected to a sonotrode body (224, 324) via a neck (222, 322), and the sonotrode head has working faces (230, 232, 330,332) extending diametrically opposite and in particular parallel to one another in the longitudinal direction thereof, which extend along a first longitudinal side (226, 228), which is connected in terms of said working faces via a second longitudinal side (234, 236, 334, 336),

it is characterized in that the preparation method is characterized in that,

a sonotrode head (220,320) is applied, the second longitudinal side (234, 236, 334, 336) of which is machined such that a cross-sectional change of the sonotrode head (220,320) is effected along the working face (230, 232, 330, 332).

8. The method according to claim 7, characterized in that the machining is carried out such that the cross-section of the sonotrode head (220,320) is greater in an end region (244, 246,344, 346) of the working surface (230, 232, 330,332) running at the end side than in a middle region of the working surface.

9. Method according to claim 7 or 8, characterized in that the second longitudinal side (234, 236) is machined in such a way that the distance of the second longitudinal side decreases, preferably continuously, starting from an end region (244) of the working surface (230, 232) running at the end face and as far as an end region (246) of the working surface running at the sonotrode side.

10. Method according to claim 7 or 8, characterized in that the machining of the second side (334, 336) is effected such that the second side obtains a concave course and the neck (322) is gradually narrowed such that a minimum cross section Q6 results, wherein the ratio Q5: Q6 of the minimum cross section Q5 of the sonotrode head (320) to the minimum cross section Q6 of the neck (322) is between 1.5:1 and 1.1:1, preferably between 1.21:1 and 1.30:1, in particular 1.26:1, and/or the ratio Q2: Q6 of the cross section Q2 of the working face (320, 322) in the edge region (344) running at the end side to the minimum cross section Q6 of the neck is between 2.0:1 and 1.1:1, preferably between 1.40:1 and 1.55:1, in particular 1.47:1, and/or the ratio Q4832: Q362 of the cross section of the sonotrode head to the Q6 of the working face (320, 322) in the end side Q631: 1, preferably between 1.12:1 and 1.20:1, in particular 1.16: 1.

11. Method according to at least claim 8, characterized in that the machining of the second longitudinal side (234, 236) is carried out such that the ratio of the cross section Q2 in the end-side end region (244) of the working face (230, 232) to the cross section Q3 in the sonotrode-side end region (246) is between 2.0:1 and 1.05:1, in particular between 1.05:1 and 1.20:1, preferably between 1.05:1 and 1.15:1, in particular about 1.1:1, and/or the ratio to the smallest cross section Q1 of the neck (222) is between 2.0:1 and 1.1:1, in particular between 1.20:1 and 2.20:1, preferably between 1.22:1 and 1.30:1, in particular about 1.26: 1.

Technical Field

The invention relates to a Sonotrode (Sonotrode) for an ultrasonic welding device, comprising a Sonotrode body having a Sonotrode head with at least one working surface extending in the longitudinal direction of the Sonotrode head for welding or soldering (Verschweissen) and/or deforming and/or cutting at least one metal weld (Schweissgut), wherein the Sonotrode head has cross sections that differ from one another along the working surface.

The invention also relates to a method for influencing the vibration behavior (Schwingungsverhalten) of a sonotrode head of an ultrasonic metal welding device for welding, deforming and/or cutting metal weld pieces, which vibrates in the longitudinal direction, wherein the sonotrode head is connected to the sonotrode via a neck (Hals) and has working faces running diametrically opposite (diamertral) and in particular parallel to one another in the longitudinal direction thereof, which extend along a first longitudinal side of the sonotrode head, which is connected in terms of said working faces via a second longitudinal side.

Background

When joining raw materials using ultrasound, the energy required for welding is introduced into the weld part in the form of mechanical vibrations, wherein the sonotrode is connected to the joining part facing it and moves the joining part. At the same time, pressure loading is carried out. The welding is carried out by the combined action of static and dynamic forces without additional raw materials. In ultrasonic metal welding, the mechanical vibrations are oriented parallel to the joint surfaces. A complex relationship occurs in the weld zone between static forces, oscillating shear forces and moderate temperature rises. For this purpose, the starting material or starting materials are arranged between a vibrating sonotrode and a stationary counter electrode (Gegenelektrode).

Ultrasonic metal welding is also used for the fluid-tight sealing and separation of small metal tubes, as is required for cooling devices, in particular air conditioners or refrigerators. The devices with which the respective welding is performed are known, for example, from the documents DE 10360623B 3 or DE 102015206866B 3.

In order to obtain a reproducible welding result of high quality, the sonotrode, i.e. the sonotrode head, is deflected essentially in its longitudinal direction, i.e. in the direction of the ultrasonic vibrations. In order to avoid or reduce a corresponding deflection extending perpendicularly to the direction of the ultrasonic vibrations, DE 502004002817C 5 provides a reinforcement (versatifung) of the sonotrode head in the region of the end face, which may be configured as a rib.

If, in ultrasonic metal welding, the vibrations are oriented parallel to the joining surface, in ultrasonic plastic welding the vibrations extend perpendicularly to the joining surface. The sonotrode head itself can have mutually different cross-sectional areas at the inlet and outlet sides, as can be seen from DE 20314781U 1.

For sonotrode heads with a working surface (which acts successively on the weld in different positions for the sake of uniformity of wear and therefore for the maximization of the degree of utilization) determined for ultrasonic metal welding, there is the disadvantage that, after the use of a new region of the working surface, a new parameterization has to be carried out in order to be able to obtain an optimum welding result. The stopping time must therefore be taken into account. Here, for example, the position is changed after a thousand welds.

Disclosure of Invention

The invention is based on the object of improving a sonotrode of the type mentioned at the outset in such a way that the stopping time is reduced by changing the welding position while the welding result is of high quality. The vibration characteristics of the sonotrode head should be optimized. Welds that maintain the same quality should be achieved.

In order to achieve this object, a sonotrode of the type mentioned at the outset is essentially developed according to the teaching of the invention in such a way that the cross section of the sonotrode head is greater in the end region (Endbereich) of the working surface, which extends at the end, than in the middle region of the working surface.

In particular, the cross section of the sonotrode head is preferably of decreasing design starting from the end region of the working surface extending at the end face up to the sonotrode-side end region of the working surface, wherein in particular a continuous change in cross section is achieved. In this case, the sonotrode head can first have a constant cross section, if necessary directly in its end face region (stirnberich), which is then reduced.

Alternatively, it is provided that the cross section of the sonotrode head, proceeding from the end region of the working surface extending at the end, first decreases and then increases to the sonotrode-side end region of the working surface. In particular, it is provided here that the cross section of the sonotrode body is smallest in a middle region of the working surface.

Surprisingly, it has been shown that by means of the special geometry of the sonotrode head of the ultrasonic metal welding device, i.e. by means of the cross-sectional variation according to the invention, the vibration behavior or the conversion ratio (Uebersetzungsverhaeltnis) is changed such that the deviation in the case of a change in the position at which welding is effected is smaller than in the case of a sonotrode with a constant cross-section. The amplitude homogenization (amplitudenvergleichmaessessiung) can be determined such that the variation in amplitude according to the welding position is smaller than in the case of a sonotrode with a constant cross section along the working face, so that more welds can be performed without having to re-determine the parameters. The stop time can be shortened, and as a result the number of welds per time unit can be increased.

In view of the sonotrode head with a first decreasing and thereafter increasing cross section, the invention is particularly characterized in that the cross section of the neck in the region of its smallest cross section is reduced compared to a sonotrode head maintaining the same cross section along the working face or faces, whereby the characteristic vibration characteristics of the sonotrode head are obtained despite the different welding locations through which homogenization of the vibration characteristics is obtained.

In accordance with the prior art, the sonotrode head should have two working surfaces which are arranged diametrically opposite and which extend in particular parallel to one another, starting from a first longitudinal side of the sonotrode head, wherein the first longitudinal side is connected to one another via a second longitudinal side. According to the invention, it is then provided that the change in the cross-sectional area of the sonotrode head in the region of the working surface is achieved by a change in the course of the second longitudinal side.

The present invention is particularly set up such that,

the cross section of the sonotrode head in the end region of the face end is Q2,

in the case of a cross-section which tapers from the end region on the end side of the working surface to the end region on the sonotrode side of the working surface, the cross-section of the sonotrode head in the end region on the sonotrode side is Q3 and the neck passes through the line or region of the minimum cross-section Q1,

in the case of a cross-sectional area which decreases first starting from the end region of the working surface extending at the end face and then increases to the sonotrode-side end region of the working surface, the sonotrode head is Q5 in the region of the smallest cross-sectional area between the end-side and sonotrode-side end regions of the working surface, wherein the cross-sectional area in the sonotrode-side end region of the working surface is Q4 and the neck passes through a line or region of the smallest cross-sectional area Q6, wherein

Q2Q 1 is between 2.0:1 and 1.1:1 and/or

Q2Q 3 is between 2.0:1 and 1.05:1 and/or

Q2Q 5 is between 2.0:1 and 1.05:1 and/or

Q2Q 6 is between 2.0:1 and 1.1:1 and/or

Q4Q 5 is between 2.0:1 and 1.05:1 and/or

Q3Q 1 is between 1.5:1 and 1.1:1 and/or

Q5Q 6 is between 1.5:1 and 1.1:1 and/or

With the secondary conditions that Q1 is less than Q2, Q3 and Q6 are less than Q2, Q4, Q5 and Q3 are less than Q2 and Q5 is less than Q2, Q4,

-wherein especially Q2: Q3 is between 1.05:1 and 1.20:1, preferably between 1.05:1 and 1.15:1, especially about 1.1:1, and/or

In particular Q5: Q6 is 1.21:1 to 1.30:1, in particular about 1.26:1, and/or

In particular Q2: Q6 is between 1.40:1 and 1.55:1, in particular about 1.47:1, and/or

In particular Q2: Q5 is between 1.12:1 and 1.20:1, in particular about 1.16:1, and/or

In particular Q2: Q1 is between 1.22:1 and 1.30:1, in particular about 1.26:1, and/or

In particular Q2: Q4 is between 1:1 and 1.04:1, in particular about 1.02: 1.

A method for influencing the vibration behavior of a sonotrode head of a sonotrode of an ultrasonic metal welding device that vibrates in the longitudinal direction, wherein the sonotrode head is connected to the sonotrode via a neck and has working surfaces running diametrically opposite and parallel to each other in its longitudinal direction, which extend along a first longitudinal side of the sonotrode head, which is connected in its turn via two second longitudinal sides, is characterized in particular in that a sonotrode head is used, the second longitudinal sides of which are machined such that a change in the cross section of the sonotrode head is effected along the working surfaces.

At least one working or welding surface extends along each first longitudinal side, along which a cutting edge (Schneidkante) optionally extends. Two working surfaces may also extend along each first side surface, between which a projection (Erhebung) with two cutting edges extends. The sonotrode geometry in this context is intended in particular for the welding and separation of small metal tubes, as is applied to cooling devices.

The second longitudinal side is formed such that the distance between the longitudinal sides decreases from the end region of the working surface extending on the end side to the end region of the working surface extending on the sonotrode side.

However, it is also possible to machine the second side of the sonotrode head such that the second side has a concave course. In particular, it is provided here that the neck is tapered such that the ratio Q2: Q6 of the cross section Q2 in the end region of the working surface running at the end face to the smallest cross section Q6 of the neck is between 2.0:1 and 1.1:1, preferably between 1.40:1 and 1.55:1, in particular approximately 1.47:1, compared to the sonotrode head with a cross section that remains the same along the working surface.

The ratio of the smallest cross section Q5 between the end regions of the running surface extending at the end sides to the smallest cross section Q6 of the neck should be between 1.5:1 and 1.1:1, preferably between 1.21:1 and 1.30:1, in particular approximately 1.26: 1.

In the case of a substantially constant reduction in cross section in the direction from the end region extending at the end side to the sonotrode-side end region of the working surface, the maximum cross section Q2 in the region of the working surface should be between 2.0:1 and 1.1:1, preferably between 1.22:1 and 1.30:1, in particular approximately 1.26:1, relative to the minimum cross section Q1 of the neck.

The cross-section Q2 in the end region on the end side of the working surface of the sonotrode head should be, compared to the cross-section Q3 in the end region on the sonotrode side of the working surface: q2: Q3 is between 2.0:1 and 1.05:1, preferably between 1.05:1 and 2.0:1, in particular between 1.05:1 and 1.5:1, preferably about 1.1: 1.

Drawings

Further details, advantages and features of the invention result not only from the claims and the features to be learned therefrom (alone and/or in combination), but also from the preferred embodiments to be learned from the following description of the drawings. Wherein:

figure 1 shows a principle view of an ultrasonic welding device,

figure 2 shows a sonotrode according to the prior art,

figure 3 shows a first embodiment of the applicator according to the invention,

figure 4 shows the applicator according to figure 3 in a top view,

fig. 5 shows a sonotrode corresponding to fig. 3, without reinforcement,

figure 6 shows the illustration according to figure 4 with a cut line,

figure 7 shows a cross-section along the line C-C in figure 6,

figure 8 shows a cross-section along the line B-B in figure 6,

figure 9 shows a cross-section along the line a-a in figure 6,

figure 10 shows a first side view of the applicator according to figure 3,

figure 11 shows a second side view of the applicator according to figure 3,

figure 12 shows a second embodiment of the applicator according to the invention,

figure 13 shows the applicator according to figure 12 in a top view,

figure 14 shows a variant of the applicator according to figure 12,

figure 15 shows the illustration according to figure 14 with a cut line,

figure 16 shows a cross-section along the line C-C in figure 15,

figure 17 shows a cross-section along the line B-B in figure 15,

figure 18 shows a cross-section along the line a-a in figure 15,

figure 19 shows a first side view of the applicator according to figure 12,

FIG. 20 shows a second side view of the applicator according to FIG. 12 and

figures 21-29 show a variation of the applicator according to figures 3-11.

The teaching according to the invention, on the basis of which the vibration characteristics of the sonotrode are improved, shall be explained in detail on the basis of the drawings, in which like elements can be provided with like reference numerals.

Detailed Description

Fig. 1 shows an ultrasonic welding device in the form of an ultrasonic welding pliers 10 in a schematic representation, which has upper and lower pliers parts 12, 14, which are arranged in a housing 16. The upper jaw 12 has, as an essential component, an ultrasonic vibration device with a sonotrode 18 arranged in the front of a housing 16, which forms a first welding jaw (Schweissbacke). Sonotrode 18 may be placed in vibration in the longitudinal direction.

Disposed opposite the applicator 18, in the lower portion of the housing 14 is a counter electrode or anvil (Amboss) 20. In this case, the anvil 20 is configured so as to be pivotable relative to the sonotrode 18 about a pivot axis, not shown, in such a way that a weld, such as a metal pipe, arranged between the working or welding surface 22 and the working surface 24 of the anvil 20 associated therewith can be cut simultaneously with the roll-off (abquetschen) and welding (durchrennenn).

The teaching according to the invention is not limited thereby. Rather, it is quite generally suitable for the construction of sonotrodes, with which a weld made of metal is to be welded or welded together and deformed.

The sonotrode 18 has a working face extending in its longitudinal direction, as is explained with reference to fig. 2. From which the applicator 18 according to the prior art can be known.

The sonotrode 118 has a sonotrode head 120 that transitions into a sonotrode body 124 via a sonotrode neck 122. The sonotrode head 120 has working faces 130, 132 in diametrically opposite first longitudinal sides 126, 128, which can preferably run parallel to one another and have a length extension L of between 10mm and 100 mm. The first longitudinal sides or faces 126, 128 are connected via second lateral faces 134, 136, which extend parallel to one another.

In order to optimize the utilization of the sonotrode 118, the change of the welding position is carried out after a preset number of welds, that is to say the material to be welded is contacted with the working surface 132 (which may also be referred to as the welding surface) in a different position of the working surface 130 at the time of welding or after rotation of the sonotrode 118.

In a typical production, the position adjustment can be carried out, for example, after 1000 welds, as a result of which wear is evened out. Thereby maximizing the utilization degree.

After the welding position has been set, the parameters must be determined again in order to achieve an optimum welding result. The corresponding parameter determination and setting is carried out by qualified personnel. For the measurement of the parameters, ultrasonic welding devices cannot be used, with the result that cost disadvantages arise due to the resulting downtime in the production process.

According to the invention, the sonotrode head is designed in such a way that no parameter measurements need to be carried out after each welding position change, since a homogenization of the amplitude or vibration behavior of the sonotrode is achieved despite the change in position of the object to be welded.

A first embodiment of the sonotrode 218 is shown in fig. 3 to 11, which follows the teaching according to the invention. The applicator 218 is likewise comprised of an applicator head 220, a neck 222, and an applicator body 224.

Along the first, opposite longitudinal sides or faces 226, 228 of the sonotrode head 220, running parallel to one another, running faces 230, 232 extend, which perform the function of a welding face and at the same time effect a deformation of the weld, as is the case when welding and roll-breaking small tubes, as explained above. Furthermore, in the exemplary embodiment, the working surfaces 230, 232 are delimited by cutting edges 245, 247, in a non-limiting manner, in order to be able to cut through the respective small tubes. For this purpose, the counter electrode associated with the sonotrode 218 or the sonotrode head 220 has corresponding edges.

The sonotrode head 220 thus has a geometry, as can be gathered in principle from fig. 2 of the document DE 10360623B 3. The edge of the anvil associated with the cutting edge may also be known from it.

The teaching according to the invention is also intended in particular for sonotrodes with two cutting edges, as can be gathered from fig. 3 of the document DE 10360623B 3. Reference is also explicitly made to the disclosure in this connection, which is therefore also the subject of the present description.

However, the invention is not limited to the corresponding embodiments. But rather is applicable to common sonotrodes with which to weld metal, i.e. also plates, litz wires, etc., in accordance with the teachings of the present invention.

The length of the neck 222 and the length of the applicator head 220 are depicted in figure 10. The height of the head 220 corresponds to the spacing of the working surfaces 230, 232.

A top view of the applicator 218 can be seen in fig. 4. The embodiment of fig. 5 differs from the embodiment of fig. 4 only in that no reinforcements 242, such as ribs, project on the end side 240 in order to reduce undesired deflections perpendicular to the direction of vibration. The reinforcement 242 follows the teaching of the document DE 502004002817C 5.

In contrast to conventional sonotrodes 118, as can be seen from fig. 2, the sonotrode head 220 has a cross-sectional profile along the working or welding surfaces 230, 232 such that the sonotrode head 220 has a larger cross-section in the region of the working surfaces 230, 232 extending at the end than in the end region of the working surfaces 230, 232 extending at the sonotrode side. The end-side region is marked with reference numeral 244 in fig. 6 and the end-side region is marked with reference numeral 246.

The distance between the second flanks 234, 236, which connect the first longitudinal flanks 226, 228, thus decreases from the end face 240 in the direction of the sonotrode body 224, as can be seen in particular from the sectional views of fig. 8 and 9. It should be noted that the sonotrode head 220 may initially have, starting from the end face 240, a region 241 in which the cross-section of the sonotrode head 220 is initially constant. However, this embodiment can be taken into account, i.e., the distance between the second flanks 234, 236 decreases from the end face 240 in the direction of the sonotrode 224.

The section according to fig. 7 is a section along the line C-C, in which the sonotrode neck 222 has the smallest cross section. The cross-section is marked with Q1. The section along the line a-a (fig. 9) is a section of the sonotrode head 220, in which end regions 244 of the end sides of the working faces 230, 232 run. The cross-section is marked with Q2.

In addition, a further section B-B, which is marked in fig. 8 with the reference Q3, is provided in the body-side end region 246 of the running surfaces 230, 232. Here, these cross sections should preferably be represented as follows:

q2: Q3 is between 1.05:1 and 1.20:1, preferably between 1.05:1 and 1.15:1, especially about 1.1: 1;

q2: Q1 is between 1.22:1 and 1.30:1, especially about 1.26: 1;

q3: Q1 is between 1.12:1 and 1.20:1, especially about 1.16: 1.

It should be noted that in principle no changes to the other components of the sonotrode 218 are required in the design of the sonotrode head 220 with respect to this, that is to say the geometry of the neck 222 and the sonotrode body 224 can correspond to the geometry of the sonotrode 118, in which the sonotrode head 120 has a cross section over the length of the working faces 130, 132 which remains the same, i.e. the side faces 134, 136 run parallel to one another.

Fig. 12 to 20 show further embodiments of a sonotrode 318 constructed according to the invention, which likewise differ from sonotrode 118 with regard to its sonotrode head 320. Regardless, the sonotrode head 320 likewise transitions into the sonotrode body 324 via the sonotrode neck 322.

If, in the isometric illustration according to fig. 12, a reinforcement 342 is provided starting from the end face 340, this is not a mandatory feature, as was explained with reference to fig. 13.

In accordance with the exemplary embodiment of fig. 3 to 11, the sonotrode head 320 has working or welding surfaces 330,332 extending along the two elongate first side surfaces 326, 328, each of which is delimited by a cutting edge 345, 347, which is associated with a corresponding cutting edge in the counterelectrode in order to be able to cut the metal tube during welding. Of course, two cutting edges can be provided on each first side 326, 628, which extend between the working and welding surfaces, as can be seen from fig. 3 of the document DE 10360623B 3.

The first longitudinal sides 326, 328 are connected via two second sides 334, 336, which have the course explained below, in order to design the sonotrode head 320 such that it has a course with a varying cross section along the working or welding surfaces 330,332 in accordance with the teachings of the present invention. The limits of the working faces 330,332 are marked with reference numerals 344, 346.

As is explained in particular with reference to the plan views of fig. 13 to 15, the sonotrode head 320 has a geometry such that the second flanks 334, 336 exhibit a concave course, i.e. the cross section in the end regions 344 at the end of the sonotrode head 320 is greater than in the middle region (section B-B in fig. 15). In the sonotrode-side end region 346, the sonotrode head 320 approximately has the cross section of the end-side end region 344. The concave course of the second side surfaces 334, 336 is such that a symmetrical course is obtained along a plane in which, on the one hand, the longitudinal axis of the sonotrode 318 extends and, on the other hand, which extends parallel to the working or welding surfaces 330, 332.

Corresponding to the sectional views according to fig. 17 and 18, the sonotrode head 320 has a cross section in the end regions 344 at the end sides of the working surfaces 330,332 of Q2 and a cross section in the middle region (i.e. in the region of the smallest cross section) of Q5. The cross-section is not shown in the sonotrode-side extended end region 346. Which preferably corresponds to the cross section Q2.

In contrast to the structure of the sonotrode 218, the change in the concave course of the second flanks 334, 336 of the neck 322 is effected such that it narrows further gradually, that is to say the minimum cross section (section C-C) Q6 is smaller than the minimum cross section Q1 in the sonotrode 218. In particular, the following cross-sectional ratios should be present:

q2: Q6 is between 1.40:1 and 1.55:1, especially about 1.47:1,

q2: Q5 is between 1.12:1 and 1.20:1, especially about 1.16:1,

q5: Q6 is between 1.21:1 and 1.30:1, especially about 1.26: 1.

The exemplary embodiment of fig. 21 to 29 corresponds essentially to the exemplary embodiment of fig. 3 to 11, with the exception that the sonotrode head 220 does not have a cutting edge running along the working surfaces 230, 232. Further, the applicator 418 has the same geometry as the applicator 214, and thus the same reference numerals are applied. The description of applicator 218 applies equally to applicator 418.