SONOTRODE HAVING OPTIMIZED SLOT GEOMETRY

Abstract

An ultrasonic vibration element which vibrates with a longitudinal ultrasonic vibration, the vibration unit is bounded in the longitudinal direction by a rear face and a front face, the front face is either intended to come into contact with a further vibration element or is designed as a sealing surface or adjoins a sealing surface which comes into contact with a material to be processed, wherein a circumferential lateral surface is provided, which connects the rear surface and the front face, the vibration element has a slit in the lateral surface, the slit has a slit length, a slit width and a slit depth, the slit depth being selected such that the slit completely penetrates the ultrasonic element, and the slit length being greater than the slit width, wherein the slit is not axially symmetrical to a slit longitudinal axis.

Claims

1. An ultrasonic vibration element which can be set into resonant vibration with a longitudinal ultrasonic vibration in a longitudinal direction, wherein the ultrasonic vibration unit is bounded in the longitudinal direction on the one hand by a rear face and on the other hand by a front face, wherein the front face is either intended to come into contact with a further ultrasonic vibration element in order to transmit the ultrasonic vibration to the further ultrasonic vibration element, or is designed as a sealing surface or adjoins a sealing surface which is intended to come into contact with a material to be processed and to transmit the ultrasonic vibration to the material to be processed, wherein a circumferential lateral surface is provided, which connects the rear face and the front face to one another, wherein the ultrasonic vibration element has a slit in the lateral surface, wherein the slit has a slit length l in a slit longitudinal direction, a slit width b in a slit transverse direction and a slit depth t in a slit depth direction, the slit longitudinal direction, the slit transverse direction and the slit depth direction being arranged orthogonally to one another, the slit depth t being selected such that the slit completely penetrates the ultrasonic element, and the slit length l being greater than the slit width b, characterized in that the slit is not axially symmetrical to a slit longitudinal axis along the slit longitudinal direction in a sectional view.

2. The ultrasonic vibration element according to claim 1, wherein the slit longitudinal direction and the longitudinal direction enclose an angle which is less than 25, preferably less than 5 and preferably 0.

3. The ultrasonic vibration element according to claim 1, wherein two slits are provided, the two slits being arranged axially symmetrically to an axis along the longitudinal direction.

4. The ultrasonic vibration element according to claim 3, wherein four slits are provided, two of the four slits being arranged axially symmetrically to an axis along the longitudinal direction.

5. The ultrasonic vibration element according to claim 3, wherein the ultrasonic vibration element has a first, second and third section, the first section having a thickness which is smaller than the thickness of the first section, wherein the second section has a varying thickness and connects the first to the third section.

6. The ultrasonic vibration element according to claim 5, wherein the first section has a sealing surface which is intended to come into contact with a material to be processed.

7. The ultrasonic vibration element according to claim 5, wherein the third section has a recess in which at least one piezo element is arranged.

8. The ultrasonic vibration element according to claim 1, wherein the slit is bounded by two longitudinal walls and two cross walls, a first of the two longitudinal walls is at least in sections further away from the slit longitudinal axis than a second of the two longitudinal axes, wherein preferably the first longitudinal wall is arranged further away from a center axis of the ultrasonic vibration element extending in the longitudinal direction than the second longitudinal wall.

9. The ultrasonic vibration element according to claim 8, wherein the two cross walls are concavely curved, the two cross walls preferably being curved with the same radius of curvature.

10. The ultrasonic vibration element according to 8, wherein the first longitudinal wall is concavely curved at least in sections.

11. The ultrasonic vibration element according to claim 2, wherein two slits are provided, the two slits being arranged axially symmetrically to an axis along the longitudinal direction.

12. The ultrasonic vibration element according to claim 4, wherein the ultrasonic vibration element has a first, second and third section, the first section having a thickness which is smaller than the thickness of the first section, wherein the second section has a varying thickness and connects the first to the third section.

13. The ultrasonic vibration element according to claim 6, wherein the third section has a recess in which at least one piezo element is arranged.

14. The ultrasonic vibration element according to 9, wherein the first longitudinal wall is concavely curved at least in sections.

15. The ultrasonic vibration element according to claim 2, wherein four slits are provided, two of the four slits being arranged axially symmetrically to an axis along the longitudinal direction, and wherein the ultrasonic vibration element has a first, second and third section, the first section having a thickness which is smaller than the thickness of the first section, wherein the second section has a varying thickness and connects the first to the third section.

16. The ultrasonic vibration element according to claim 15, wherein the first section has a sealing surface which is intended to come into contact with a material to be processed, and wherein the third section has a recess in which at least one piezo element is arranged.

17. The ultrasonic vibration element according to claim 16, wherein the slit is bounded by two longitudinal walls and two cross walls, a first of the two longitudinal walls is at least in sections further away from the slit longitudinal axis than a second of the two longitudinal axes, wherein preferably the first longitudinal wall is arranged further away from a center axis of the ultrasonic vibration element extending in the longitudinal direction than the second longitudinal wall, and wherein the two cross walls are concavely curved, the two cross walls preferably being curved with the same radius of curvature.

18. The ultrasonic vibration element according to 17, wherein the first longitudinal wall is concavely curved at least in sections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further advantages, features and possible applications will become clear from the following description of a preferred embodiment and the associated figures.

[0026] It shows:

[0027] FIG. 1 a perspective view of an ultrasonic vibration element of the invention and

[0028] FIG. 2 a partially sectioned plan view of the ultrasonic vibration element of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a perspective view of an embodiment of an ultrasonic vibration element 1 according to the invention. A front face 2 designed as a sealing surface 2 can be seen, which is intended to come into contact with a material to be processed. The rear face (not shown in the figure) is arranged opposite the front face 2. The front face 2 and the rear face are connected to each other via a circumferential lateral surface 3.

[0030] The ultrasonic vibration element 1 has three sections in the direction of its longitudinal axis 9, namely a first section 6, the thickness of which essentially corresponds to the width of the sealing surface 2, a third section 8, which is designed to be significantly thicker than the first section 6, and a second section 7, the thickness of which varies and which is arranged between the first section 6 and the third section 8.

[0031] In this embodiment, the ultrasonic vibration element has a recess in the third section 8, in which a plurality of piezo elements 5 are arranged, with which the ultrasonic vibration element 1 can be set into ultrasonic vibration. The piezo elements 5 have a through opening through which a screw 18 engages in this embodiment. An upper part 17 is pressed against the piezo elements 5 with the aid of a nut 16, so that the piezo elements 5 are held between the upper part 17 and the ultrasonic vibration element 1.

[0032] To prevent the mechanical stresses within the material from becoming too great and to optimize the position of unwanted secondary resonances, four slits 4 are provided that completely penetrate the material in a depth direction.

[0033] According to the invention, the slits have a special shape. The slits have two cross walls 10 as well as a first longitudinal wall 11 and a second longitudinal wall 12.

[0034] The slits extend along a slit longitudinal direction 15, which in the example shown forms an angle of 0 with the longitudinal direction 9 of the ultrasonic vibration element, i.e. runs parallel to it.

[0035] The two cross walls 10 of the slits are curved. The second longitudinal wall of the slit 12 is also parallel to the longitudinal axis 9. The longitudinal wall 11 of the slit 4 has a concave curvature.

[0036] Basically, the slits according to the invention could be made by first making a slit with two parallel longitudinal walls and then making a corresponding notch in the first wall 11. Several notches 13, 14 can also be made in one of the slits, as can be seen in the two slits 4 arranged closer to the rear face.

REFERENCE SIGNS

[0037] 1 Ultrasonic vibration element [0038] 2 Sealing surface, front face [0039] 3 Lateral surface [0040] 4 Slit [0041] 5 Piezo element [0042] 6 First section [0043] 7 Second section [0044] 8 Third section [0045] 9 Longitudinal axis, longitudinal direction [0046] 10 Crosswall [0047] 11 First longitudinal wall [0048] 12 Second longitudinal wall [0049] 13, 14 Notch [0050] 15 Slit longitudinal direction [0051] 16 Nut [0052] 17 Upper part [0053] 18 Screw