Sealing tool for sealing a base into a sleeve

Abstract

The present invention relates to a sealing tool for sealing a base into a sleeve with a sonotrode and an anvil with an end face, wherein the anvil has a cavity in the end face for receiving the sleeve and base, wherein the cavity has an inner surface portion designed as a first sealing surface, the sonotrode has a portion which can be guided into the cavity in a longitudinal direction and has a circumferential surface portion designed as a second sealing surface, wherein the sonotrode and anvil can be moved to and fro relative to each other in a longitudinal direction between a starting position, in which the sonotrode is arranged outside the cavity, and a welding position, in which the sonotrode is positioned inside the cavity in such a manner that the two sealing surfaces are arranged opposite each other and a gap for receiving the sleeve and base remains between the two sealing surfaces, characterized in that an inner surface portion serving as a guide portion adjoins the first sealing surface in the longitudinal direction.

Description

[0001] Sealing tool for sealing a base into a sleeve

[0002] The present invention relates to a sealing tool for sealing a base into a sleeve. Furthermore, a method for connecting a base to a sleeve is described.

[0003] When manufacturing containers, e.g., for holding liquids or bulk materials, a shell element, the so-called sleeve, is often first cut from a sheet of material and joined together at its edges, forming the sleeve, for example, a hollow cylinder. However, other shapes, such as rectangular, square, or even kidney-shaped, are also possible.

[0004] A base is glued into the sleeve to seal it on one side. The base can be circular, for example, with the edges bent by approximately 90° so that they are aligned approximately parallel to the casing element. The edges of the base are then glued to the casing element. The sleeve with the glued-in base can then serve as a container for liquids or bulk materials, for example.

[0005] Instead of gluing the base into the sleeve, it has already been proposed in EP 1 819 506 B1 to seal the base into the sleeve using an ultrasonic tool.

[0006] For this purpose, a sonotrode and an anvil with a front face are used, with the anvil having a cavity in the front face for receiving the sleeve and the base inserted into the sleeve. The cavity has an inner surface section designed as the first sealing surface, while the sonotrode has a section that can be guided longitudinally into the cavity and a peripheral surface section designed as the second sealing surface. The cavity can completely penetrate the anvil, so that the sleeve can be guided into the cavity from one side and the base from the other side.To seal the base, the sonotrode and anvil are moved back and forth relative to each other in a longitudinal direction between a starting position, in which the sonotrode is arranged outside the cavity, and a welding position, in which the sonotrode is positioned inside the cavity such that the two sealing surfaces are arranged opposite each other and a gap remains between the two sealing surfaces to accommodate the sleeve and base. In the welding position, the sonotrode is excited with acoustic ultrasonic vibrations so that the material positioned between the first and second sealing surfaces is welded. Thermoplastic materials are generally used here. However, other materials, such as composites made of thermoplastic and elastomer materials, are also conceivable.

[0007] Particularly in containers with relatively large volumes and high-density contents, it can happen that the welded joints loosen over time and contents leak from the container. This is undesirable.

[0008] Based on the described prior art, the object of the present invention is therefore to further develop a sealing tool of the type mentioned above in such a way that a secure sealing connection between the base and the sleeve can be ensured. In this context, a method for connecting the sleeve and base is described that ensures a secure and permanent connection even under heavy loads.

[0009] With regard to the sealing tool, this task is solved by the fact that an inner surface section serving as a guide section is connected to the first sealing surface in the longitudinal direction.

[0010] This measure ensures that the base does not have to be connected to the sleeve at the outer end, but rather the sleeve extends beyond the base. This means that, following sealing, the protruding section of the sleeve can be crimped. The crimped section can then also be connected to the edge section of the base, so that it is bonded to the sleeve material on both sides. By crimping, part of the force exerted by the contents on the base is transferred via the crimped section of the sleeve, thus relieving the seal.

[0011] In a preferred embodiment, the first and / or second sealing surface forms an angle a with the longitudinal axis which is greater than 0°, preferably between 5° and 35°, particularly preferably between 7° and 20° and most preferably between 10° and 15'.

[0012] This measure ensures that the relative movement of the sonotrode relative to the anvil in the direction of the longitudinal axis can exert a welding force on the material arranged between the two sealing surfaces.

[0013] In a particularly preferred embodiment, both the first and the second sealing surface are inclined relative to the longitudinal axis.

[0014] It is particularly advantageous if the gap between the first sealing surface and the second surface, in which the rejecting material is received, has a non-uniform width. This can be achieved, for example, by designing the gap in such a way that it has a conical cross-section.

[0015] Therefore, if the first and second sealing surfaces are flat, they each form a different angle with the longitudinal axis. A particularly preferred embodiment is one in which the angle formed by the second sealing surface with the longitudinal axis is greater than the angle formed by the first sealing surface with the longitudinal axis.

[0016] In a further preferred embodiment, the first sealing surface and / or the second sealing surface have a recess extending in the longitudinal direction. This measure allows the sleeve, which consists of a web-like material fastened together at its edges, to overlap at its edges, which improves the strength of the sleeve.

[0017] Because the edge areas overlap, the sleeve is somewhat thicker in this area than in all other areas. According to this embodiment, a corresponding recess should be provided in which the overlapping areas of the sleeve lie.

[0018] This recess can be formed either in the first sealing surface of the sonotrode or in the second sealing surface of the anvil. Alternatively, both the first sealing surface and the second sealing surface can have a corresponding recess, so that during the welding process, the bead formed due to the overlap lies partly in the recess of the first sealing surface and partly in the recess of the second sealing surface.

[0019] In a further preferred embodiment, it is provided that the sonotrode has a sonotrode end face which adjoins the first sealing surface and is oriented perpendicular to the longitudinal axis, in which a channel opening is arranged, via which a vacuum can be applied to a base which is adjacent to the sonotrode end face.

[0020] This design has the advantage that the base can be transported with the help of the sonotrode to the location where the points are welded to the sleeve. The base is placed on the sonotrode face so that the edges of the base, which are bent at almost 90° to the base surface, rest against the first sealing surface.

[0021] In order to ensure that the soil remains in its position during the movement of the sonotrode and in particular when the soil is immersed in the sleeve, a channel opening is provided in the sonotrode end face in this embodiment, through which air can be sucked in, with the result that a soil resting on the sonotrode end face is sucked in and thus held in place.

[0022] In a further preferred embodiment, it is provided that the cavity of the anvil has an inner surface section serving as a holding section for the sleeve, in which a channel opening is arranged, via which a vacuum can be applied to a sleeve resting on the holding section.

[0023] This measure also facilitates the positioning of the sleeve on the inner surface of the anvil. Because air can be extracted through the channel in the anvil, which opens in the holding section, the sleeve is sucked in and held firmly to the holding section of the attachment. In a preferred embodiment, the holding section adjoins the first sealing surface, so that the first sealing surface is arranged longitudinally between the holding section and the guide surface.

[0024] In a further embodiment, the cavity has longitudinally adjacent inner surface sections with different inner diameters. This measure allows individual inner surface sections to be used to guide and hold the sleeve, while another inner surface section, namely the second sealing surface, is used for welding.

[0025] In a further preferred embodiment, it is provided that the cavity of the anvil has an expanding cross-section on its side facing the sonotrode.

[0026] This facilitates threading the sonotrode into the anvil cavity. If, contrary to expectations, the sonotrode is not perfectly positioned relative to the anvil, it will then encounter the outwardly widening section of the inner surfaces as it moves from the starting position to the welding position, and will then be guided into its desired position.

[0027] In a further preferred embodiment, the anvil is mounted in a floating manner in a plane perpendicular to the longitudinal direction. This floating mounting allows the anvil to deflect, to a limited extent, forces applied in the plane perpendicular to the longitudinal direction.

[0028] It is particularly advantageous if the anvil is constructed in two parts, with the two parts arranged side by side in the longitudinal direction. Preferably, the part of the anvil having the second sealing surface is mounted in a floating manner in a plane perpendicular to the longitudinal direction. In a preferred embodiment, the holding section is not provided on the same part of the anvil to which the first sealing surface is attached.

[0029] In a further preferred embodiment, at least the part of the anvil having the second sealing surface consists of two detachable members arranged side by side in a plane perpendicular to the longitudinal direction. This measure allows at least one member to be moved away from the other member after sealing the lid in the sleeve, ensuring easier removal of the processed material.

[0030] The tools described can be used in a procedure with the following steps:

[0031] A) Providing a sealing tool as just described, B) Positioning the sleeve within the cavity so that one section of the sleeve rests against the guide surface and another section of the sleeve rests against the first sealing surface,

[0032] C) Positioning the base on the sonotrode so that edge sections of the base are in contact with the second sealing surface and

[0033] D) Positioning the sealing tool in the welding position and stimulating the sonotrode with an ultrasonic vibration.

[0034] Thus, the base is not positioned directly at the end of the sleeve and connected to it, but slightly further inside, so that another section of the sleeve is connected to the outside of the sealing surface, which is not welded to any part of the base.

[0035] This has the advantage that, in a subsequent step, the outer section of the sleeve—that is, the section of the sleeve that was in contact with the guide section of the anvil during the welding process in step D)—can be bent over so that it rests against the edge section of the base. In this position, the edge section is encompassed by the sleeve on both sides. The bent section of the sleeve can then also be connected to the edge section of the base.

[0036] Further advantages, features, and possible applications will become clear from the following description of some preferred embodiments and the associated figures. They show:

[0037] Figure 1 is an exploded view of a first embodiment of the invention,

[0038] Figure 2 is a sectional view of the embodiment of Figure 1,

[0039] Figure 3 is a detailed enlargement of the view in Figure 2,

[0040] Figure 4 is a copy of the view of Figure 3 with the sleeve and base drawn in, and Figure 5 is an exploded view of a second embodiment of the invention.

[0041] Figure 1 shows an exploded view of a first embodiment of a sealing tool according to the invention. The sealing tool is designed to seal a base into a sleeve. The sealing tool comprises a sonotrode 1 and an anvil 2, 3. In this embodiment, the anvil 2, 3 is formed in two parts and comprises a first part 2 and a second part 3, which can be screwed together.

[0042] The anvil 2, 3 has a cavity that extends completely through the anvil. The sonotrode 1 has a sonotrode end face 8, which is delimited by a second sealing surface 7, which forms a peripheral surface section of the sonotrode. Adjacent to the second sealing surface 7 is a cylindrical peripheral surface section 6, which in turn is connected to another cylindrical peripheral surface section 4 via a constricted section 5.

[0043] The sonotrode end face 8 has a plurality of vacuum bores 9 through which a base, which is to be sealed into a sleeve by means of the sealing tool, can be sucked in and thus held.

[0044] In the embodiment shown, the sonotrode 1 is rotationally symmetrical about its longitudinal axis. The sonotrode 1 can be moved back and forth relative to the anvil 2, 3 in the longitudinal direction, i.e., along the longitudinal axis, between a starting position, in which the sonotrode is arranged outside the cavity, and a welding position, in which the sonotrode is arranged inside the cavity.

[0045] Figure 2 shows a sectional view of the embodiment of Figure 1 in the welding position. One of the vacuum bores 9 is visible, which is connected to a central bore 10 through which air can be extracted. In the welding position, the sonotrode 1 and the anvil 2, 3 are arranged such that they do not touch each other.

[0046] Figure 3 shows an enlarged detail of Figure 2. It can be seen that the cavity of the anvil part 3 has an inner surface section designed as the first sealing surface 11. In the welding position, the sonotrode 1 is positioned within the cavity such that the two sealing surfaces, i.e., the first sealing surface 11 of the anvil part 3 and the second sealing surface 7 of the sonotrode 1, are arranged opposite one another, leaving a gap between the two sealing surfaces to accommodate the sleeve and base.

[0047] In the longitudinal direction, an inner surface section of the anvil, serving as a guide section 13, adjoins the first sealing surface 11. In the starting position, the guide section 13 is arranged closer to the sonotrode 1 than the first sealing surface 11. As will be described in more detail below, the guide section 13 is used to guide a section of the sleeve that protrudes above the base. The sonotrode 1 has an outer surface section 6 adjoining the second sealing surface 7, which, in the welding position, is positioned opposite the guide section 13 and at a distance from it.

[0048] In the longitudinal direction, on the opposite side of the first sealing surface 11, a holding section 12 is provided, which is essentially hollow-cylindrical in shape and has an inner diameter approximately corresponding to the outer diameter of the sleeve. Adjoining the holding section 12 is a further inner surface section 14, which has a larger inner diameter than the holding section 12.

[0049] The first sealing surface 11 forms an angle with the longitudinal axis that is greater than 0° and ideally between 10° and 15°. Likewise, the second sealing surface 7 forms an angle with the longitudinal axis that is greater than 0° and ideally between 10° and 15°. In the embodiment shown, the angle formed by the second sealing surface with the longitudinal axis is greater than the angle formed by the first sealing surface with the longitudinal axis. The difference between the enclosed angles in the embodiment shown is only 1°. The different angles mean that the gap width between the first sealing surface 11 and the second sealing surface 7 is not constant.

[0050] The functionality of the involved inner and outer surface sections is clearly illustrated in Figure 4, which essentially corresponds to the representation in Figure 3, but additionally schematically shows a base element 15 and a sleeve 17. In the example shown, the base element 15 is circular and rests against the sonotrode end face. The outer ring section 16 of the base element 15 is bent over and rests against the second sealing surface 7.

[0051] The sleeve 17 rests against the inner contour of the anvil 2, 3. In the welding position shown in the figure, when the sonotrode 1 is subjected to an ultrasonic vibration, the outer ring section 16, which rests against the second sealing surface 7, and the section of the sleeve 17 that rests against the first sealing surface 11 are fused together. Due to the different angles that the first and second sealing surfaces 7 and 11 form with the longitudinal axis, molten material will arrange itself in a wedge shape within the gap between the two sealing surfaces and thereby press the base 15 and sleeve 17 into the correct position. It can be seen that the sleeve 17 has been inserted into the anvil such that a section 18 of the sleeve 17 protrudes beyond the first sealing surface 11.In order that the section 18 is oriented approximately parallel to the longitudinal axis and thus approximately perpendicular to the base 15, the guide section 13 is provided, against which the section 18 of the sleeve 17 rests.

[0052] The section 18 of the sleeve is flanged, i.e. bent, in a further processing step and also sealed with the annular section 16 of the base, so that the bent annular section 16 of the base 15 is enclosed on both sides by the sleeve 17.

[0053] Although not shown in this embodiment, the inner surface of the anvil can have a substantially longitudinally extending recess in which a weld seam of the sleeve can be accommodated. The sleeve is often made from a rectangular sheet of material, with opposite edges of the rectangular blank being glued or welded together. Since the material is somewhat thicker at the weld seam, the weld seam can then be inserted into the correspondingly provided recess.

[0054] Figure 5 shows an exploded view of a second embodiment of the invention. This differs from the embodiment shown in Figure 1 only in that the shape of the sonotrode end face 8' of the sonotrode 1' is not circular, but essentially rectangular. The inner contour of the anvil 2', 3' was adapted accordingly. This tool is intended for sealing rectangular bases into corresponding sleeves.

[0055] List of reference symbols

[0056] 1, 1' sonotrode

[0057] 2, 2', 3, 3' anvil 4, 6 circumferential surface section

[0058] Section 5

[0059] 7 Sealing area

[0060] 8, 8' sonotrode face

[0061] 9 vacuum holes 10 central hole

[0062] 11 first seal area

[0063] 12 stopping section

[0064] 13 Guide section

[0065] 14 Inner surface section 15 Floor

[0066] Section 16

[0067] 17 Sleeve

[0068] Section 18

Claims

P a t e n t a n s p r ü c h e 1. Sealing tool for sealing a base into a sleeve, comprising a sonotrode and an anvil with an end face, wherein the anvil has a cavity in its end face for receiving the sleeve and base, the cavity having an inner surface section designed as a first sealing surface, the sonotrode having a section that can be guided longitudinally into the cavity and a circumferential surface section designed as a second sealing surface, wherein the sonotrode and anvil can be moved back and forth relative to each other in a longitudinal direction between a starting position in which the sonotrode is arranged outside the cavity and a welding position in which the sonotrode is positioned inside the cavity such that the two sealing surfaces are arranged opposite each other and a gap for receiving the sleeve and base remains between the two sealing surfaces, characterized in thatthat an inner surface section serving as a guide section adjoins the first sealing surface in the longitudinal direction.

2. Sealing tool according to claim 1, characterized in that the first and / or second sealing surface encloses an angle α with the longitudinal axis which is greater than 0°, preferably between 5° and 35°, particularly preferably between 7° and 20° and best between 10° and 15°.

3. Sealing tool according to claim 1 or 2, characterized in that the first and the second sealing surface each enclose an angle α with the longitudinal axis which is greater than 0°, wherein the first and the second sealing surface enclose unequal angles with the longitudinal axis, so that the gap has a conical cross-section, wherein preferably the angle which the second sealing surface encloses with the longitudinal axis is greater than the angle which the first sealing surface encloses with the longitudinal axis.

4. Sealing tool according to one of claims 1 to 3, characterized in that the first sealing surface and / or the second sealing surface have a longitudinally extending recess.

5. Sealing tool according to one of claims 1 to 4, characterized in that the sonotrode has a sonotrode end face adjoining the first sealing surface and oriented perpendicular to the longitudinal axis, in which a channel opening is arranged. is, via which a vacuum can be applied to a surface adjacent to the sonotrod end face.

6. Sealing tool according to one of claims 1 to 5, characterized in that the cavity of the anvil has an inner surface section serving as a holding section for the sleeve, in which a channel opening is arranged through which a vacuum can be applied to a sleeve adjoining the holding section.

7. Sealing tool according to one of claims 1 to 6, characterized in that the cavity has longitudinally adjacent inner surface sections with different inner diameters.

8. Sealing tool according to one of claims 1 to 7, characterized in that the cavity of the anvil has an expanding cross-section on its side facing the sonotrode.

9. Sealing tool according to one of claims 1 to 8, characterized in that the anvil is floatingly mounted in a plane perpendicular to the longitudinal direction.

10. Sealing tool according to one of claims 1 to 9, characterized in that the anvil is formed in two parts, wherein the two parts are arranged next to each other in the longitudinal direction, wherein preferably the part of the anvil which has the second sealing surface is floatingly mounted in a plane perpendicular to the longitudinal direction.

11. Sealing tool according to claim 10, characterized in that at least the part of the anvil which has the second sealing surface consists of two detachable links which are arranged next to each other in a plane perpendicular to the longitudinal direction.

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