Sonotrode with coated inlet section

Abstract

The invention relates to a sonotrode or ultrasonic welding device for ultrasonic processing of materials, which comprises a sealing surface suitable for contacting the workpiece, a back surface opposite the sealing surface and a circumferential lateral side surface connecting the sealing surface to the back surface, the lateral side surface having two side surfaces arranged approximately parallel to one another and two end surfaces arranged approximately parallel to one another.In order to provide a sonotrode or ultrasonic welding device for processing materials, which at least reduces damage to the material and at the same time does not impair the production rate, it is proposed according to the invention that the sealing surface has a convexly curved inlet part adjacent to the lateral side surface, and that the sealing surface has a coating at least in one part.

Description

[Technical Field]

[0001] The present invention relates to a sonotrode for ultrasonically processing materials, which has a sealing surface intended to be in contact with the workpiece, a back surface opposite the sealing surface, and circumferential lateral sides connecting the sealing surface to the back surface, the lateral sides having two side faces arranged approximately parallel to one another and two end faces arranged approximately parallel to one another. [Background technology]

[0002] Usually, the side and end faces are arranged parallel to one another, but there are also applications in particular where several sonotrodes are arranged next to one another with their end faces facing one another, so that their end faces are not exactly parallel to one another.

[0003] Furthermore, the present invention relates to an apparatus for ultrasonically machining materials, comprising a sonotrode of the above type, a counter-tool with a sealing surface, and a material supply, the sealing surface of the counter-tool being arranged opposite the sealing surface of the sonotrode so that the workpiece can be guided by the material supply through the gap formed by the two opposing sealing surfaces during machining.

[0004] To process materials ultrasonically, the sonotrode of the device is activated with ultrasonic vibrations. The direction of propagation of the ultrasonic vibrations extends between the back surface of the sonotrode and the sealing surface. The ultrasonic vibrations of the sonotrode cause local heating of the material located in the gap between the sealing surface of the sonotrode and the sealing surface of the counter tool. This local heating causes the different layers of material located in the gap to fuse together, thus forming a solid connection that cannot be released without causing damage.

[0005] Various ultrasonic machining processes are known in the prior art. For example, in one variant, the material is continuously moved through a gap between the sonotrode and the counter-tool, and is machined by the sonotrode continuously or at specific intervals. Alternatively, systems are known in which the material is initially placed in the gap and is not moved for the duration of the ultrasonic machining.

[0006] Ultrasonic waves can also be used in particular to weld together several layers of material, where the individual layers of material are usually fed into the gap from different directions, since the feed rollers that feed the material into the device require a corresponding space.

[0007] Furthermore, in an effort to conserve resources, thinner and more easily damaged welded materials are now being used.Typical products produced by ultrasonic processing are, for example, tubular packaging materials, but also hygiene articles, which are often made of several layers of fiber-containing materials joined together.

[0008] Therefore, during ultrasonic machining, special care must be taken to ensure that the feeding and processing of the material does not result in any undesired destruction of the material and therefore does not impair the product quality. Sonotrodes known from the prior art often have geometrical consequences that cause the workpiece to be damaged immediately when fed into the gap between the sonotrode and the counter tool, especially when special materials such as nonwovens are involved. Furthermore, the shape of known sonotrodes can also cause material damage when the material is fed into the ultrasonic machining device at an angle to the sonotrode sealing surface. This results in material breakage during the machining process and a decrease in product quality.

[0009] These disadvantages arise in particular when several layers of material are to be welded together, which are fed from different directions into the gap between the sonotrode and the counter-tool, as some of the material rubs against the edges of the sonotrode or counter-tool and is consequently damaged.

[0010] It is known from the prior art to reduce these drawbacks by reducing the force and speed used during ultrasonic machining. However, this results in less product being produced in the same amount of time. Some materials can only be ultrasonically machined if the material is not moved during machining. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention is therefore based on the problem of providing a sonotrode or ultrasonic welding device for processing materials, which at least reduces damage to the material and at the same time does not impair the production rate. [Means for solving the problem]

[0012] According to the invention, this problem is solved by a sonotrode of the type described above, in which the sealing surface has a convexly curved inlet portion adjacent to the lateral side surface, and the sealing surface has a coating at least in part.

[0013] The convexly curved inlet portion of the sealing surface means that material introduced into the gap between the sonotrode and the counter-tool experiences less friction on the outer surface of the sonotrode and is therefore less damaged. Furthermore, a coating applied to the sealing surface in some areas reduces friction between the workpiece and the sealing surface of the sonotrode. The coating is therefore preferably applied to the area of ​​the sonotrode that comes into contact with the material.

[0014] In one embodiment, the inlet portion has a radius of curvature R e and preferably has a radius of curvature R e is at least 3 mm, preferably at least 5 mm, more preferably at least 7 mm.

[0015] The design of the convexly curved inlet section with a constant radius of curvature is advantageous from the standpoint of production technology. Furthermore, the claimed radius of curvature offers the advantage that in this case, friction between the workpiece and the sonotrode is particularly effectively reduced. At the same time, the vibration behavior of the sonotrode, and thus the ultrasonic processing results of the ultrasonic welding device, are not significantly impaired by the selected radius of curvature.

[0016] In another embodiment, the end face is smaller than the side faces and the convexly curved inlet section is adjacent to one of the two side faces. A correspondingly shaped sonotrode offers the advantage that it can process material over a large width, which width preferably corresponds to the extent of the side faces.

[0017] If the feed direction is defined as the direction in which the material is guided in the gap between the sonotrode and the counter tool, in one particular embodiment, the side faces are arranged one after the other perpendicular to the feed direction and the end faces of the sonotrode are arranged parallel to the feed direction.

[0018] In a further embodiment, the sealing surface has a convexly curved outlet portion adjacent the other of the two side surfaces, preferably the outlet portion having a radius of curvature R a and is particularly preferably curved with a radius of curvature R a is the radius of curvature R e and the radius of curvature R e and R a are equal. This embodiment offers the advantage that, on the one hand, it is easy to manufacture from a production engineering point of view, and, on the other hand, the processed material can also be discharged from the ultrasonic processing device without further damage due to friction between the sonotrode and the material. Furthermore, it has vibration-related advantages. Furthermore, from the viewpoint of vibration engineering, similar radii of the inlet and outlet sections are advantageous, and incorrect mounting of the sonotrode can be avoided due to the symmetrical design.

[0019] In a further embodiment, the sonotrode has a pressure of 2R at its sealing face end. e ≦d≦20Re , preferably 2R e ≦d≦10R e , particularly preferably 2R e ≦d≦5R e , particularly preferably 2R e ≦d≦3R e The sonotrode has a thickness d for which the formula (1) applies. In other words, the sonotrode is designed at its sealing surface end so that in one limiting case the entire sealing surface is convexly curved, and in another limiting case the sealing surface is essentially flat, i.e., has an additional non-curved area. However, this flat area is limited to 18 times, preferably 8 times, particularly preferably 3 times, and particularly preferably 1 time the radius of the inlet part. The exact design of the sealing surface can be adapted to different applications, for example, depending on how large the area to be simultaneously processed by the sonotrode is.

[0020] In a further embodiment, the sonotrode has a recess extending at least partially across the sealing surface, with a coating disposed within the recess, the coating preferably having a thickness corresponding to the depth of the recess, such that the coated surface of the sonotrode is flush with the uncoated surface of the sonotrode.

[0021] This recess offers the advantage that the coating is more stably fixed on the sealing surface of the sonotrode, thus reducing loosening of the coating due to forces occurring during machining and increasing the service life of the sonotrode according to the invention in ultrasonic machining devices.

[0022] In a further embodiment, the recess has a continuously varying depth at its edge, so that the coating placed in the recess has a thickness that decreases toward the uncoated surface. On the one hand, this provides manufacturing advantages; on the other hand, the coating in this case can be of higher quality because there are no corners in the recess that may not be completely filled with the coating. Such insufficiently coated areas lead to faster breakdown of the coating and thus to a shorter service life of the sonotrode.

[0023] In a further embodiment, the recess extends into one side surface, preferably into both side surfaces, which ensures that the coating also completely covers or extends beyond the inlet or outlet portion and thus particularly effectively avoids friction between the workpiece or machined material and the sonotrode.

[0024] In another embodiment, the two end faces are spaced apart by a distance A s and an extension line A of the recess in a direction extending from one end face to the other end face is a For 0.5A s a ≦1A s applies, that is, in this embodiment, in the limiting case, the recess extends from one end face completely across the sealing face to the other end face, facilitating insertion of the recess and the covering.

[0025] In another embodiment, the recess does not extend completely from one of the end faces to the other, but an edge area of ​​at least one of the end faces remains, which confines the coating, which also increases the stability of the coating on the sonotrode sealing face, since forces acting on the end faces of the sonotrode cannot act directly on the coating.

[0026] In a further embodiment, the cladding is convexly curved in at least one portion. The convex curvature of the cladding, like the convex curvature of the inlet and outlet portions, has the advantage of reducing friction with the workpiece.

[0027] In a further embodiment, the coating consists of hard metals and preferably non-oxide ceramics. These materials are particularly stable and characterized by a long service life, which allows the sonotrode according to the invention to have a long service life. At the same time, friction with the workpiece can be significantly reduced.

[0028] In a further embodiment, the sealing surface has at least one groove, preferably a plurality of grooves aligned parallel to one another and extending in a direction from one side to the other.​

[0029] Such grooves are typically used to guide threads within the grooves and produce collectable or collected materials. For this purpose, one or more threads are placed between two material webs and guided through the gap between the sonotrode and the counter tool. By guiding the threads within the sonotrode grooves, ultrasonic processing of the material system occurs only in those areas of the sealing surface where no grooves are formed. This generally results in welding of the two outer layers of material, but not the threads. This can ultimately be used to collect the material.

[0030] In one embodiment, the at least one groove is arranged exclusively within the sheath. This offers the advantage that sonotrodes of standard shapes can be manufactured and only the sheath has to be adapted to the respective application. The formation of the groove in the sheath also offers the advantage that the surface of the groove is also covered, and therefore no damage can occur to the material within or even at the edges of the groove.

[0031] In another embodiment, grooves are introduced directly into the sealing surface of the sonotrode and coated with a thin film coating to reduce wear on the material and on the sonotrode.

[0032] Furthermore, the problem underlying the present invention is solved by an apparatus for ultrasonically processing materials, which comprises a sonotrode according to one of the above-mentioned embodiments, a counter-tool having a sealing surface arranged opposite the sealing surface of the sonotrode so that the workpiece can be guided through the gap formed by the two opposing sealing surfaces during processing, and a material supply part by means of which the material can be guided through the gap.

[0033] In a further embodiment, the material supply is designed such that the material or at least a portion of the material is guided through the inlet portion, which can prevent damage to the material supplied through the inlet portion, particularly when ultrasonically machining multiple layers of material supplied from different directions into the gap between the sonotrode and the counter-tool.

[0034] Further advantages, features and possible applications will become apparent from the following description of two embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 shows a three-dimensional schematic diagram of a sonotrode according to one embodiment of the present invention. [Figure 1a] FIG. 1a shows a cross-sectional view of the sonotrode of the embodiment of the invention shown in FIG. [Figure 1b] FIG. 1b is a schematic enlarged view of the sealing face end of the sonotrode shown in FIG. [Figure 2] FIG. 2 shows a cross-section of a sonotrode with a coating according to one embodiment of the present invention. [Figure 3] FIG. 3 shows a cross-sectional view of a sonotrode with a coating according to a further embodiment of the invention. [Figure 4] FIG. 4 shows a schematic diagram of an ultrasonic machining device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] 1, 1a and 1b, the sonotrode 1 has on its sealing surface 2 a convexly curved inlet portion 7 and a convexly curved outlet portion 8. The convexly curved inlet portion 7 is adjacent to a side surface 3 of the sonotrode 1, while the convexly curved outlet portion 8 is adjacent to the other side surface 4 of the sonotrode 1. Both the convexly curved inlet portion 7 and the convexly curved outlet portion 8 each have a constant radius of curvature R of 7.5 mm. e and R aIn alternative embodiments, the inlet and outlet sections may be curved with different radii of curvature.

[0037] The side surfaces 3, 4 connect two end surfaces 5, 6 of the sonotrode 1, which form the lateral sides of the sonotrode 1, which in turn connect the rear surface of the sonotrode 1 to the sealing surface 2 of the sonotrode 1. As shown in Figure 1, the end surfaces 5, 6 are also smaller than the side surfaces 3, 4.

[0038] The sonotrode 1 has an inlet section 7 with a radius of curvature R at its sealing face end. e It has a thickness d equal to three times the thickness of the

[0039] The above-described structure is also present in the embodiment of the sonotrode shown in Figures 2 and 3. Figures 2 and 3 therefore show only a portion of the sonotrode.

[0040] In the sonotrode 1 according to the embodiment of the invention shown in Figure 2, the sealing surface 2 has a recess 21 in which a coating 9 is arranged. The coating 9 has a thickness corresponding to the depth of the recess 21, such that the coated surface 22 of the sonotrode 1 is flush with the uncoated surface 23 of the sonotrode 1.

[0041] Furthermore, the recess 21 has a portion at its edge where the depth changes continuously, so that the coating 9 disposed in the recess 21 has a thickness that decreases toward the uncoated surface 23. Furthermore, the coating 4 is also convexly curved and made of a non-oxide ceramic.

[0042] However, in the embodiment shown in FIG. 3, the recess 21 extends into both sides 3 , 4 of the sonotrode 1 .

[0043] In the schematic diagram of an ultrasonic machining device shown in Figure 4, a sonotrode 1 according to the invention is shown together with a counter tool 11. A workpiece system 10 is guided in the gap formed between the sealing surface 2 of the sonotrode 1 and the sealing surface of the counter tool 11. In this case, the workpiece system 10 consists of two material layers 12, 13 and a threaded section 14 arranged between the two material layers 12, 13. To guide the threaded section 14, the sealing surface 2 of the sonotrode 1 has a number of grooves extending in the direction from one side surface 3 to the other side surface 4.

[0044] One of the layers of material 12 is guided over the inlet portion 7 of the sealing surface 2 of the sonotrode 1. The other layer of material 13 is guided over the sealing surface of the cylindrical counter-tool 11. In this way, damage to the system of the workpiece by the ultrasonic machining device is prevented. The present disclosure also includes the following inventions. The first aspect is A sonotrode (1) for ultrasonically machining a material (10), comprising: The sonotrode (1) a sealing surface (2) intended to come into contact with the workpiece (10); A back surface facing the sealing surface (2); a circumferential lateral side surface connecting the sealing surface (2) with the back surface, The lateral side surface has two side surfaces (3, 4) arranged substantially parallel to each other and two end surfaces (5, 6) arranged substantially parallel to each other, The sealing surface (2) has a convexly curved inlet portion (7) adjacent to the lateral side, The sealing surface (2) is a sonotrode (1) characterized in that it has a coating (9) at least in part. The second aspect is The inlet portion (7) has a radius of curvature R e and preferably has a radius of curvature R e is at least 3 mm, and preferably said radius of curvature R e is at least 5 mm, and particularly preferably the radius of curvature R e is at least 7 mm. The third aspect is The sonotrode (1) of the first or second aspect is characterized in that the end faces (5, 6) are smaller than both of the side faces (3, 4) and the convexly curved inlet portion (7) is adjacent to one of the side faces (3) of both of the side faces (3, 4). The fourth aspect is The sealing surface (2) has a convexly curved outlet portion (8) adjacent to the other side (4) of the two side surfaces (3, 4), and preferably the outlet portion (8) has a radius of curvature R a and particularly preferably has a radius of curvature R a is the radius of curvature R e and preferably the radius of curvature Re and most preferably the radius of curvature R e and the radius of curvature R a In a third aspect, the sonotrode (1) is characterized in that: The fifth aspect is The sonotrode (1) preferably has a sealing surface end (20) of 2R e ≦d≦20R e , preferably 2R e ≦d≦10R e , particularly preferably 2R e ≦d≦5R e , particularly preferably 2R e ≦d≦3R e The sonotrode (1) according to any one of the first to fourth aspects, characterized in that it has a thickness d to which the following formula applies: The sixth aspect is The sonotrode (1) of any one of the first to fifth aspects is characterized in that the sonotrode (1) has a recess (21) extending over at least a portion of the sealing surface (2), a coating (9) is arranged in the recess (21), and the coating (9) preferably has a thickness corresponding to the depth of the recess (21) so that the coated surface (22) of the sonotrode (1) is flush with the uncoated surface (23) of the sonotrode (1). A seventh aspect is A sonotrode (1) in a sixth aspect, characterized in that the recess (21) has a portion whose depth changes continuously at its edge so that the coating (9) placed in the recess (21) has a thickness that decreases in the direction of the uncoated surface (23). The eighth aspect is A sonotrode (1) according to the sixth or seventh aspect, characterized in that the recess (21) extends to one side surface (3, 4) and preferably to both side surfaces (3, 4). A ninth aspect is The two end faces (5, 6) are spaced apart by an interval A s and the extension line A of the recess (21) in the direction extending from one end face (5) to the other end face (6) is A About 0.5A s <A A A ≦ 1 s The sonotrode (1) according to any one of the sixth to eighth aspects is characterized in that the following is applied. A tenth aspect is The sonotrode (1) according to any one of the first to ninth aspects, wherein the coating (9) is convexly curved in at least a portion thereof. An eleventh aspect is The sonotrode (1) according to any one of the first to tenth aspects, characterized in that the coating (9) is made of a hard metal and preferably a non-oxide ceramic. A twelfth aspect is The sonotrode (1) according to any one of the first to eleventh aspects, characterized in that the sealing surface (2) has at least one groove, preferably a plurality of grooves arranged parallel to one another and extending in a direction from one side surface (3) to the other side surface (4). A thirteenth aspect is A sonotrode (1) according to a twelfth embodiment, characterized in that at least one groove is arranged exclusively in the coating (9). A fourteenth aspect is 1. An apparatus for ultrasonically machining a material, comprising: The ultrasonic processing device comprises: A sonotrode (1) according to any one of the first to thirteenth aspects; a counter tool (11) having a sealing surface opposite to the sealing surface (2) of the sonotrode (1), the sealing surface being arranged so that the workpiece (10) can be guided through a gap (15) formed by the two opposing sealing surfaces during machining; and a material supply section capable of guiding the workpiece (10) through the gap (15). A fifteenth aspect is The device according to a fourteenth aspect, characterized in that the material supply section is designed so that the workpiece (10) is guided over the inlet section (7). [Explanation of symbols]

[0045] 1 Sonotrode 2 Sonotrode sealing surface 3. Aspects 4 Sides 5 End face 6 End face 7 Entrance section 8 Exit part 9 Covering 10 materials 11 Counter Tools 12 material layers 13 Material layer 14 Thread section 15 Gap 20 Sealed end of sonotrode 21 Recess 22 Covered surface 23 Uncoated surface

Claims

1. A sonotrode (1) for ultrasonically processing a material (10), comprising: The sonotrode (1) a sealing surface (2) intended to come into contact with the workpiece (10); a back surface facing the sealing surface (2); a circumferential lateral side surface connecting the sealing surface (2) with the back surface, The lateral side surface has two side surfaces (3, 4) arranged substantially parallel to one another and two end surfaces (5, 6) arranged substantially parallel to one another, The sealing surface (2) has a convexly curved inlet portion (7) adjacent to the lateral side, The sealing surface (2) has a coating (9) at least in part, The sonotrode (1) has a recess (21) extending over at least a portion of the sealing surface (2), and a coating (9) is arranged in the recess (21).

2. The inlet portion (7) has a radius of curvature R ｅ 2. The sonotrode (1) according to claim 1, characterized in that it is curved at .

3. A sonotrode (1) according to claim 2, characterized in that the radius of curvature R e is at least 3 mm.

4. 4. The sonotrode (1) according to claim 1, wherein the end faces (5, 6) are smaller than both of the side faces (3, 4) and the convexly curved inlet portion (7) is adjacent to one of the side faces (3, 4).

5. 3. The sonotrode (1) according to claim 2, characterized in that the sealing surface (2) has a convexly curved outlet portion (8) adjacent to the other side (4) of the two side surfaces (3, 4).

6. A sonotrode (1) as claimed in claim 5, wherein the outlet portion (8) is curved with a radius of curvature R a , which differs from the radius of curvature R e by no more than 50%.

7. The sonotrode (1) has a sealing surface end (20) of 2R ｅ 5. Sonotrode (1) according to any one of claims 1 to 4, characterized in that it has a thickness d, for which the formula ≦d≦20Re applies.

8. A sonotrode (1) as described in any one of claims 1 to 7, characterized in that the coating (9) has a thickness corresponding to the depth of the recess (21) so that the coated surface (22) of the sonotrode (1) is flush with the uncoated surface (23) of the sonotrode (1).

9. 9. The sonotrode (1) according to claim 8, characterized in that the recess (21) has a portion whose depth changes continuously at its edge so that the coating (9) arranged in the recess (21) has a thickness that decreases in the direction of the uncoated surface (23).

10. 8. Sonotrode (1) according to claim 6 or 7, characterized in that the recess (21) extends to one of the lateral surfaces (3, 4).

11. The two end faces (5, 6) are spaced apart by a distance A ｓ and an extension line A of the recess (21) in a direction extending from one end face (5) to the other end face (6) is Ａ About 0.5A ｓ <A Ａ ≦1 A ｓ A sonotrode (1) according to any one of claims 1 to 10, characterized in that:

12. Sonotrode (1) according to any one of claims 1 to 11, characterized in that the covering (9) is convexly curved in at least one part.

13. Sonotrode (1) according to any one of claims 1 to 12, characterized in that the coating (9) consists of a hard metal.

14. 14. Sonotrode (1) according to any one of claims 1 to 13, characterized in that the sealing surface (2) has at least one groove extending in a direction from one side surface (3) towards the other side surface (4).

15. 15. Sonotrode (1) according to claim 14, characterized in that at least one groove is arranged exclusively in the coating (9).

16. 1. An apparatus for ultrasonically machining a material, comprising: The ultrasonic processing device comprises: A sonotrode (1) according to any one of claims 1 to 15, a counter tool (11) having a sealing surface opposite to the sealing surface (2) of the sonotrode (1), the sealing surface being arranged so that the workpiece (10) can be guided through a gap (15) formed by the two opposing sealing surfaces during machining; and a material supply section capable of guiding the workpiece (10) through the gap (15).

17. 17. Apparatus according to claim 16, characterized in that the material supply is designed in such a way that the workpiece (10) is guided over the inlet section (7).

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