Processing element with engraved portion, and ultrasound processing apparatus

Abstract

The invention relates to a processing element, such as a sonotrode or an anvil, for processing a material. The processing element has a substantially cylindrical or cylinder-segment-shaped sealing face, which is designed to come into contact with the material during processing, wherein the processing element is designed to be rotated about a longitudinal axis during processing such that the sealing face rolls on the material to be processed, wherein the sealing face has an engraved area in which the sealing face has notches so that base portions are formed by the notches and surround a plurality of structural elements having top faces, which structural elements are higher than the base portions.

Description

[0001] Processing element with engraving section and ultrasonic processing device

[0002] The present invention relates to a processing element for processing a material, having a substantially cylindrical or cylinder-segment-shaped sealing surface that is intended to come into contact with the material during processing. The processing element can, for example, be a sonotrode or an anvil that is rotated about its longitudinal axis during processing. The sealing surface is arranged on the peripheral surface of the processing element, and the material to be processed is moved between the sonotrode on the one hand and the anvil on the other hand at the peripheral speed of the processing element, such that the sealing surface rolls on the material to be processed. The sealing surface is cylindrical or cylinder-segment-shaped with respect to a cylinder axis that coincides with the longitudinal axis.

[0003] Both processing elements are known which have a cylindrical sealing surface which rolls on the material to be processed and thereby creates, for example, a continuous longitudinal seam, and processing elements which only have one - or more - cylindrical segment-shaped sealing surface(s), so that when the processing element rotates, the cylindrical segment-shaped sealing surface only comes into contact with the material to be processed once per revolution, for example to create a transverse sealing seam.

[0004] In particular, when such a processing element is used for ultrasonic processing of materials, it is usually referred to as a sonotrode if it is subjected to an ultrasonic vibration, or as an anvil if it is arranged opposite a sonotrode.

[0005] For example, an ultrasonic processing device can have both a roller-shaped sonotrode and a roller-shaped anvil, between which the web-shaped material is guided and processed while the material is pressed by the sonotrode towards the anvil. Frequently, a plurality of sealing surfaces are provided which protrude radially above a support surface. In some applications, the sealing surface is engraved, i.e., has a pattern that is transferred to the material to be processed during processing. The sealing surface thus has an engraving surface in which the sealing surface has incisions such that the incisions form base sections which enclose a plurality of structural elements with head surfaces that are raised compared to the base sections. The engraving surface can cover the entire sealing surface.By creating incisions, areas are formed in the sealing surface that are located closer to the longitudinal axis. These are the so-called base sections. Within these sections located closer to the longitudinal axis, island-like structures then form that are elevated compared to the base sections, i.e., are at a greater distance from the longitudinal axis. These sections have head surfaces.

[0006] Because the sealing surfaces do not come into continuous contact with the material being processed, since material processing is only desired when the cylindrical segment-shaped sealing surfaces engage with the material, it is difficult to adjust the appropriate welding force with which the sonotrode presses against the anvil. It is known to use appropriate control mechanisms that, for example, measure the corresponding force and compare it with a target value.

[0007] Whenever a corresponding transverse seal seam is to be produced, the cylindrical segment-shaped sealing surface engages with the material. Due to the elasticity of the holder that fastens the sonotrode or anvil to a machine stand, which cannot be completely ruled out, the counterforce exerted by the sonotrode and anvil leads to a relative displacement between the sonotrode and counter tool on the one hand, and the machine stand on the other. Due to the rotation of the processing element, however, the sealing surfaces abruptly engage with the material, so that they are subjected to an abrupt force impulse. At this moment, it is difficult for the force control to set the appropriate force. The abrupt engagement also causes the sonotrode and possibly also the counter tool to vibrate due to their attachment to the machine stand.In other words, due to the abrupt impact that the sealing surfaces of the anvil exert on the sonotrode via the material to be processed, a relative displacement of the sonotrode with respect to the machine stand occurs.

[0008] This is followed by a decaying oscillation of the sonotrode around a rest position, with the force exerted by the sonotrode on the counter-tool, and thus also the welding result, varying with the oscillation. Similarly, if the cylindrical segment-shaped support surface disengages from the material, an abrupt relaxation of the sonotrode occurs, which is also undesirable.

[0009] The described problem is already known from DE 10 2014 115 538 A1. There, it was proposed to equip the sealing surface with inlet areas curved with a radius of curvature smaller than the greatest distance of the sealing surface from the cylinder axis. This results in the distance between the sealing surface of the anvil and the sealing surface of the sonotrode decreasing gradually rather than abruptly, thus reducing the described problem.

[0010] However, the requirements for constant welding force at ever-increasing processing speeds are constantly increasing, so that this solution reduces the problem but does not completely solve it.

[0011] Based on the described prior art, it is therefore an object of the present invention to provide a processing element which further reduces the described problems.

[0012] According to the invention, the engraving surface has an engraving edge section arranged at the edge of the engraving surface and a main engraving section adjoining the engraving edge section in the circumferential direction, wherein the head surfaces of the structural elements within the main engraving section are further away from the longitudinal axis than the head surfaces of the structural elements within the engraving edge section. This achieves an effect similar to that described in DE 10 2014 115 538 A1, although this effect is now achieved alternatively or in combination via the design of the engraving surface.

[0013] Since, when the machining element rotates around the longitudinal axis, the engraving edge section first comes into contact with the material to be machined and this has head surfaces of the structural elements that are arranged closer to the longitudinal axis than is the case in the main engraving section that subsequently comes into contact with the material to be machined, there is a less abrupt increase in force and the control of the welding force is significantly simplified.

[0014] In a particularly preferred embodiment, a second engraving edge section adjoins the main engraving section in the circumferential direction opposite the engraving edge section, which second engraving edge section has the same features as the first engraving edge section, so that at the end of the processing by means of the engraving surface, an engraving edge section engages again, the head surfaces of the structural elements of which are arranged closer to the longitudinal axis and thus provide a greater distance between the head surfaces of the structural elements and the opposite processing element.

[0015] In a particularly preferred embodiment, within the engraving edge region, the distances of the head surfaces from the longitudinal axis become monotonically smaller in the circumferential direction from the side of the engraving edge region bordering the main engraving section to the side facing away from the main engraving section. Monotonically smaller means that from structural element to structural element in the circumferential direction, the head surfaces are arranged closer to or at the same distance from the longitudinal axis as the immediately preceding head surface.

[0016] In a preferred embodiment, the distances of the head surfaces from the longitudinal axis become strictly monotonically smaller, which means that from structural element to structural element in the circumferential direction the head surface has an increasingly smaller distance from the longitudinal axis.

[0017] For example, in the engraving edge area, the head surfaces of the structural elements can lie in one plane.

[0018] It is also possible for the engraving edge area itself to have different sections in the circumferential direction, within which the head surfaces of the structural elements lie in one plane, with the planes having different distances from the longitudinal axis, so that the head surface of a structural element further away from the main engraving surface never has a greater distance from the longitudinal axis.

[0019] In an alternative embodiment, the head surfaces of the structural elements in the engraving edge region lie on an imaginary cylindrical surface whose radius is smaller than the radius of curvature of the sealing surface. This measure also ensures that the distance between the head surfaces and the opposite processing element gradually decreases upon contact during processing and, if a second engraving edge region is provided, the distance continuously increases upon disengagement. It is understood that the processing element can have multiple sealing surfaces. In a preferred embodiment, the width of the engraving edge section in the circumferential direction is between 0.2 and 15 mm and preferably between 0.4 and 10 mm.

[0020] Furthermore, the present invention relates to an ultrasonic processing device with a sonotrode and an anvil, wherein the sonotrode and / or anvil is designed as a processing element as described above, wherein the ultrasonic processing device has an operating state in which the sonotrode is subjected to an ultrasonic vibration and the processing element is rotated about its longitudinal axis, wherein a material guide device is provided and configured such that, in the operating state, it moves a material to be processed between the sonotrode and anvil at a material speed that corresponds or substantially corresponds to the peripheral speed of the processing element. In most cases, the peripheral speed will correspond exactly to the material speed.However, there are also cases where the material speed and the peripheral speed differ slightly, which changes the shape of the material during machining.

[0021] Further advantages, features, and possible applications of the present invention will become clear from the following description of preferred embodiments. They show:

[0022] Figure 1 is a schematic representation of an embodiment of the prior art, Figure 2 is a schematic representation of a first embodiment of the invention, Figure 3 is a schematic representation of a second embodiment of the invention and

[0023] Figure 4 is a schematic representation of a third embodiment of the invention.

[0024] Figure 1 shows a schematic representation of the embodiments known from the prior art. A sectional view through part of a processing element 1, such as a sonotrode, is shown schematically, the section being made perpendicular to the longitudinal axis of the processing element. In the figure, the longitudinal axis is thus aligned perpendicular to the plane of the drawing. A part of the engraving section is shown, which has a large number of structural elements 2, 3, 4. The representation is greatly enlarged, so that it cannot be seen in the figure that the processing element has a curved, namely cylindrical or partially cylindrical, surface. The rotation of the processing element 1 about the longitudinal axis takes place in such a way that first the structural element 4, then the structural element 3 and finally the structural element 2 comes into contact with the material to be processed.

[0025] In Figure 1, all three structural elements shown are at the same distance from the longitudinal axis. Typically, the machining element has a much larger number of structural elements, e.g., dozens, all of which have end surfaces (i.e., surfaces facing away from machining element 1) that are at the same distance from the longitudinal axis.

[0026] Figure 2 shows a first embodiment of a processing element 11 according to the invention with structural elements 12, 13 and 14. It can be seen that the structural element 12 or its head surface is at a greater distance from the longitudinal axis than the two structural elements 13, 14. There is therefore a main engraving section 15 and an engraving edge section 16, whereby the height of the structural elements or the distance of the head surfaces from the longitudinal axis is smaller in the engraving edge section 16 than in the main engraving section 15. In the example shown, the material to be processed therefore first comes into contact with the structural element 14, then with the structural element 13 and finally with the structural element 12. As a rule, the main engraving section 15 has significantly more structural elements 12, all of which have the same height or whose head surfaces are at the same distance from the longitudinal axis.

[0027] In the illustrated embodiment, it can be seen in the engraving edge section 16 that the height of the structural elements 13, 14, or the distance of their head surfaces from the longitudinal axis, increases successively in the direction of the main engraving section S 15. However, it would also be possible for all structural elements in the gray war, apart from section 16, to have the same height, as long as this height is less than the height of the structural element 12 in the main engraving section 15.

[0028] Figure 3 schematically shows a second embodiment of a processing element according to the invention. As in the embodiment of Figure 2, the processing element 21 has a main engraving section 25 and an engraving edge section 26. Here, too, the heights or the distances between the head surfaces of the structural elements 22, 23, 24 are smaller in the region of the engraving edge section than in the main engraving section. In the example shown, the head surfaces of the structural elements are inclined. In the particular embodiment shown, the head surfaces of the structural elements 22, 23 and 24 all lie in one plane. However, this is not absolutely necessary. The head surfaces do not all have to lie in one plane. Furthermore, the inclination of the head surfaces can vary from structural element to structural element.

[0029] Figure 4 shows a third embodiment of a machining element 31. Here, too, there is a main engraving section 35 and an engraving edge section 36. The head surfaces of the structural elements 32, 33, 34 are arranged closer to the longitudinal axis in the engraving edge section 31 than in the main engraving section 35. The head surfaces of the structural elements 32, 33, 34 are all curved and, in this preferred embodiment, lie on an imaginary cylindrical surface, which significantly facilitates the manufacture of the structural elements 32, 33, and 34.

Claims

P a t e n t a n s p r ü c h e 1. A processing element for processing a material, such as a sonotrode or an anvil, having a substantially cylindrical or cylinder-segment-shaped sealing surface, which is intended to come into contact with the material during processing, wherein the processing element is intended to be rotated about a longitudinal axis during processing so that the sealing surface rolls on the material to be processed, wherein the sealing surface has an engraving surface in which the sealing surface has incisions so that base sections are formed by the incisions, which enclose a plurality of structural elements with head surfaces that are raised relative to the base sections, characterized in that the engraving surface has an engraving edge section arranged at the edge of the engraving surface and a main engraving section adjoining the engraving edge section in the circumferential direction,wherein the head surfaces of the structural elements within the main engraving section are further away from the longitudinal axis than the head surfaces of the structural elements within the engraving edge section.

2. Processing element according to claim 1, characterized in that within the engraving edge region, the distances of the head surfaces from the longitudinal axis in the circumferential direction from the side of the engraving edge region which borders on the main engraving section to the side which is facing away from the main engraving section become monotonically smaller, wherein preferably within the engraving edge region, the distances of the head surfaces from the longitudinal axis in the circumferential direction from the side of the engraving edge region which borders on the main engraving section to the side which is facing away from the main engraving section become strictly monotonically smaller.

3. Processing element according to one of the preceding claims, characterized in that in the engraving edge area the head surfaces of the structural elements lie in one plane.

4. Processing element according to one of the preceding claims, characterized in that in the engraving edge area the head surfaces of the structural elements lie on an imaginary cylindrical surface whose radius is smaller than the radius of curvature of the sealing surface.

5. Processing element according to one of the preceding claims, characterized in that the processing element has several sealing surfaces.

6. Machining element according to one of the preceding claims, characterized in that in the circumferential direction on the engraving main section on the side facing away from the engraving edge section, a further engraving edge section is arranged, which has the same properties as the engraving edge section.

7. Ultrasonic processing device with a sonotrode and an anvil, wherein the sonotrode and / or anvil is designed as a processing element according to one of claims 1 to 6, wherein the ultrasonic processing device has a processing state in which the sonotrode is subjected to an ultrasonic vibration and the processing element is rotated about its longitudinal axis, wherein a material guide device is provided and designed such that it moves a material to be processed in the processing state between the sonotrode and the anvil at a material speed which corresponds or substantially corresponds to the peripheral speed of the processing element.

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