DE2711305A1 - DEVICE FOR GENERATING ULTRASONIC WAVES - Google Patents

Description

Herne 1, 8000 Munich 40,

Frelllgralhstrasse 19 _{nI,, aua} _ |. "Eisenacher Strasse 17

PO Box Mo LJipi.-lfig. H. Π. Ο3ΠΓ Pat. Betzier

Dlpl.-PhyS. Eduard BetZler Telephone: 38 30 11

^{510 u} Dipl.-Ing. W. Herrmann-Trentepohl * ³⁰¹³

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Bahrpatente Herne PATENTANWÄLTE Babetzpat Munich

Telex 0822 »853 Telex 5215360

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Bayerische Vereinsbank Munich 952 Dresdner Bank AG Herne 7-520 Postal check account Dortmund 558 68-467

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Mecasonic S.A., Bas-Montheux, F-74100 Annemasse / France

Device for generating ultrasonic waves

The invention relates to a device for generating ultrasonic vibrations with a sonotrode, which is under the Effect of an ultrasonic transducer can be excited to longitudinal vibrations.

In particular, the invention relates to a device of this type which generates radial ultrasonic vibrations, and in general for any industrial use and in particular for the field of thermoplastic materials, in particular for the continuous connection of sheets or webs made of such materials.

It is known that a metal rod vibrating at half the wavelength has an antinode of the longitudinal amplitude at each end and in the vicinity of the transverse median plane has an oscillation node of the longitudinal amplitude. Of the Node of oscillation of the amplitude corresponds in reality to one

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Anterior vibration of the radial oscillation as well as an antinode of the stress.

The effect of compression and expansion due to the longitudinal vibration, conjugate to the shape of the rod, it allows radial waves of high amplitude near the node of vibration to achieve the longitudinal vibrations in resonance with them.

One has already thought of the part of the rod or the sonotrode which is excited by these radial vibrations as To use working tools and to provide a device with which radial vibrations of maximum amplitude can be achieved. Sonotrodes that oscillate at half the longitudinal wavelength have therefore been developed, the profile of which is determined in such a way that in order to achieve a radial oscillation of high amplitude in the central plane in resonance with the longitudinal oscillations.

The manufacture of such sonotrodes has proven difficult, if not impossible.

The object of the invention is to provide a device as described above Specify kind which solves the above problem, but does not have the disadvantages of the known devices.

The invention therefore relates to a device for generating of ultrasonic vibrations, especially for processing or welding thermoplastic plastic materials, in which the directly or via an amplifier to an ultrasonic vibration transmitter connected sonotrode is excited to longitudinal vibrations with half the wavelength and in which the Part of the part of the sonotrode excited to radial vibrations in resonance with the longitudinal vibrations is used as an active or working organ, and is characterized in that the Sonotrode a hollow first part made of two half waves, in which the

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second half-wave consists of a tube, and a second part, consisting of a ring, which is in the oscillation node zone the second half-wave is arranged and incorporated into its mass, the ring being the active organ of the sonotrode forms.

Further features and advantages of the invention are intended below with reference to the description of exemplary embodiments and with reference to the drawings are explained in more detail. The drawings show in

Fig. 1 is a front view for explaining the first

Stage in the production of an inventive Contraption;

FIG. 2 shows a representation in vertical section of the sonotrode according to FIG. 1;

3 shows a representation in partial section to explain the second stage in the production of a device according to the invention; and in

4 shows a partial section of the device according to the invention.

The first goal, that of the device to be explained in more detail below was based on, was to achieve a radial oscillation on a ring 14 (see. Fig. 1 and 2). With the help of a known ultrasonic device with a transmitter 10 and an amplifier 12 was the inside diameter D_, the outside diameter D. and the thickness E is determined so that the ring 14 vibrates with radial waves without a black zone, i.e. without a point with the amplitude Zero. All parameters were determined so that the radial frequency is approximately 20 kHz.

During the first phase it was found to be impossible

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is to make a full disk vibrate in such a way, and that only one ring makes it possible to obtain radial waves.

The second phase was based on longitudinal vibrations Generate radial vibrations. A hollow sonotrode 16 {cf. Fig. 3) with two half waves ^ produced, the second half-shaft 17 consists of a tube. The dimensions of the sonotrode 16 were determined in such a way that that this oscillates in the longitudinal direction at exactly the same frequency of the ring 14 of the first phase, namely 20 kHz.

It should be noted that the longitudinal oscillation of the tube 17, which consists of the second half-wave, inevitably generates radial vibrations in the vicinity of the vibration nodes. It is precisely the vibrational nodal zone of this Rohres 17, which was used in the third phase to set the ring in vibration.

For this third and last phase (cf. FIG. 4) one has a sonotrode designed identically to the sonotrode according to FIG. 3 produced, but which has a ring 20 carved out of the mass in the oscillation node zone of the second half-wave, which is identical to the ring according to FIGS. 1 and 2.

It has been found that in this way there is a complete and perfect radial oscillation on the outer diameter of this ring 20 under the condition that the sonotrode 16 of the second phase and the ring 14 of the first phase exactly to the the same frequency are calibrated, with one element, namely the sonotrode 16 or 18 in the longitudinal direction and the other Element, namely the ring 14 or 20 swing in the radial direction.

In this way a vibrating element 18 is available, directly to the without an intermediate amplifier

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Encoder 10 can be connected. However, it can also be sent to the encoder 10 via one or more amplifiers connected in between be connected.

To such a vibrating head or a molette continuously to be used, for example, in continuous welding, cleaning, machining or other applications of Ultrasound, it is sufficient to rotate the welding head equipped with the molette around its axis and to support it to hold on a rotatable anvil or support and the material or materials to be processed between the molette and the To let support pass, with the support according to the thicknesses with the same speed or with rotates at different speeds.

It was found that the results obtained with the above-described sonotrode were obtained in continuous welding tests were significantly better than the results obtained with conventional sonotrodes.

- Claim: -

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Claims (1)

Claim Device for generating ultrasonic vibrations, in particular for processing or welding thermoplastic plastics materials, in which the directly or via
an amplifier connected to an ultrasonic vibration transmitter sonotrode for longitudinal vibrations with half
Wavelength is excited and at which the part of the radial vibrations in resonance with the longitudinal vibrations
excited part of the sonotrode is used as an active or working organ, and is characterized in that the sonotrode has a hollow first part (18) made of two half-waves, in which the second half-wave consists of a tube, and a second part consists of a ring (20 ), which is arranged in the oscillation node zone of the second half-wave and incorporated into its mass, the ring forming the active organ of the sonotrode. 709851/0673 ORIGINAL INSPECTED