Shrink cap and method of making shrink cap

Abstract

A shrink cap (10) for receiving a temperature dependent switch (12). The constriction cap (10) comprises an open first end (18) for sliding onto the switch (12), and a closed second end (20) closed by a welded or embossed seam (22) extending from a closed end face (24) arranged in the region of the second end (20) and created by the welded or embossed seam (22). The welded or embossed seam (22) is shaped such that a shaped portion (32) of the welded or embossed seam (22) abuts either directly against the end face (24) or against the end face (24) by intervening cement.

Description

Field of the Invention

[0001] The present invention relates to a shrink cap and a method of manufacturing a shrink cap. The present invention also relates to a temperature-dependent switch having a shrink cap according to the present invention in a shrunk state. Background Art

[0002] A general shrink cap and a general method of manufacturing such a shrink cap are disclosed in EP 0 857 562 B1.

[0003] Such shrink caps are typically loose and are pushed onto an electrical device to be protected (such as a temperature-dependent switch), and then shrunk by using hot air to form a sheath that protects the device from dirt, moisture, and electrical contact with other components. The connecting elements of the device are typically configured as stranded wires or cables and then protrude from the sheath.

[0004] Such shrink caps are typically produced by first cutting a length of heat-shrinkable tubing from a heat-shrinkable tube, and then forming a welded or embossed seam at one of the two ends of the heat-shrinkable tubing section. For this purpose, the heat-shrinkable tubing section is squeezed together at the end, and a welded or embossed seam is formed, for example, by two welding dies that act on the end of the heat-shrinkable tubing section from opposite sides by pressure and heat.

[0005] Since the welded or embossed seam is formed by pressing one end of the heat-shrinkable tube together and joining the pressed-together longitudinal halves of the heat-shrinkable tube, the wall thickness of the welded or embossed seam is typically approximately twice the wall thickness of the rest of the heat-shrinkable tube. This results in a relatively hard and rigid welded or embossed seam.

[0006] The welded or embossed seam protrudes from the closed end face, which is formed by the welded or embossed seam on the heat-shrinkable tube or shrink cap, respectively. Due to the manufacturing process, the free protruding end along the welded or embossed seam usually has very sharp edges. When the shrink cap is shrunk onto the device to be protected, such sharp edges remain.

[0007] Many process steps are typically carried out manually, whether when assembling a device with a shrink cap or when further processing a device equipped with a shrink cap, and the personnel performing these process steps must perform very delicate manual work, so they cannot wear protective gloves.

[0008] Due to the sharp edges of the welded or embossed seam, this type of manual work repeatedly causes injury to the personnel, which is of course a major drawback.

[0009] Therefore, in order to avoid these injuries, personnel generally do not grasp the sheathed component by squeezing the shrink cap itself, but rather by grasping the connecting cable. However, this typically results in the connection between the connecting cable and the sheathed component being weakened or even completely broken during the required further operations, such that devices made from these components often exhibit malfunctions.

[0010] In particular, if the device is, for example, a temperature-dependent switch that protects a coil from overheating, the switch encapsulated in the shrink cap is in direct contact with the coil (e.g., the coil of an electric motor). The switch is electrically connected in series with the coil, and if the temperature of the coil exceeds a predetermined value, the circuit is interrupted. For this purpose, a bimetallic switch mechanism is arranged inside the temperature-dependent switch in a known manner.

[0011] In order to reliably implement this protection function, the switch needs to be arranged inside the coil or at least very close to the coil. The sharp edges of the shrink cap would thus also cause damage to the coil, which is of course also disadvantageous.

[0012] According to EP0857562B1, the above-mentioned problem is solved by reprocessing the shrink cap after a weld or embossed seam has already been formed. During this post-processing, a forming punch is used to bend the weld or embossed seam. By this bending, the free ends of the weld or embossed seam with sharp edges are rolled up or folded, such that, so to speak, the weld or embossed seam no longer protrudes from the front of the shrink cap in an upright manner.

[0013] This measure effectively prevents the above-mentioned problem of personnel injury and the risk of damage to other devices.

[0014] However, there is still potential for improvement in the manufacture of such shrink caps. For example, it has been shown that shrink caps whose weld or embossed seams are bent by 90° or more, as described in EP 0 857 562 B1, become mechanically unstable and may thus be more prone to breakage. This in turn results in an open area in the shrink cap, and thus the protective function of the shrink cap may be fundamentally lost. In addition, this may damage the voltage resistance or high-voltage resistance of the shrink cap, which are important properties that the shrink cap must guarantee, especially when used for temperature-dependent switches. Summary of the Invention

[0015] Therefore, an object of the present invention is to provide a shrink cap and a method for manufacturing such a shrink cap, by means of which the above-mentioned problems can be eliminated or at least reduced. Thus, in particular, the aim is to reduce the risk of damage or injury that such a shrink cap may cause, while ensuring the mechanical stability, tightness, and high-voltage resistance of the shrink cap.

[0016] According to the present invention, this object is solved by a shrink cap for sliding onto a temperature-dependent switch, wherein the shrink cap includes an open first end for sliding onto the switch and a closed second end closed by a welded or embossed seam, the welded or embossed seam extending from a closed end face arranged in the region of the second end and generated by the welded or embossed seam, wherein the welded or embossed seam is shaped such that a shaped portion of the welded or embossed seam abuts directly or indirectly against the end face via an intervening bonding agent.

[0017] According to other aspects of the present invention, the above object is solved by a method for manufacturing a shrink cap, the method having the following steps:

[0018] a) Providing a heat-shrinkable tube section, the heat-shrinkable tube section including a first opening at its first end and a second opening at its second end,

[0019] b) Squeezing together the shrink tube section at the second end of the shrink tube section and generating a welded or embossed seam to close the second opening and form a closed end face in the region of the second end,

[0020] Characterized in that it further has the following steps:

[0021] c) Shaping a portion of the welded or embossed seam such that the shaped portion of the welded or embossed seam abuts directly against the end face or abuts against the end face via an intervening bonding agent.

[0022] Compared with that proposed in EP 0 857 562 B1, according to the present invention, the welded or embossed seam not only bends, folds or rolls up at an angle of 90° or more towards the end face of the shrink cap, but is also shaped such that it at least partially contacts the end face. Preferably, the welded or embossed seam is folded at about 90° and placed against the end face of the shrink cap such that at least a part of the welded or embossed seam abuts directly or indirectly against the end face of the shrink cap via an intervening bonding agent.

[0023] This has several advantages: First, the shrink cap and thus also the device to which the shrink cap is applied (e.g., a temperature-related switch) are further shortened. This smaller size is advantageous both in terms of bulk storage of the shrink cap and in terms of handling and installation options for the shrink cap. In addition, it has been shown that by applying the welded or embossed seam to the end face of the shrink cap, the risk of injury and damage is further reduced because the sharp edges of the welded or embossed seam can be fully applied to the end face of the shrink cap such that the sharp edges no longer protrude from the shrink cap at all and are thus hardly accessible. In addition, it has been shown that this creates a double or multi-layer wall at this end of the shrink cap because the welded or embossed seam against this end additionally increases the wall thickness of the shrink cap at this end. This in turn not only creates further mechanical stability. Preliminary tests by the applicant have also shown that this can greatly improve the high-voltage resistance of the shrink cap. While conventional shrink caps show a high-voltage resistance in the range of 1.5 kV - 2.5 kV, the shrink cap according to the invention can achieve a high-voltage resistance of 3.5 kV or higher.

[0024] Therefore, the above object is fully solved.

[0025] In an improved embodiment, the welded or embossed seam includes a free end and an end adjacent to the end face, wherein the formed part of the welded or embossed seam that directly abuts the end face or abuts the end face through an intervening bonding agent extends over the region between the free end and the end adjacent to the end face.

[0026] Therefore, preferably, the welded or embossed seam contacts the end face of the shrink cap at least through a central portion extending between the free end and the end adjacent to the end face.

[0027] In other improved embodiments, preferably, more than 50% of the area of the side of the welded or embossed seam that abuts the end face directly abuts the end face or abuts the end face through an intervening bonding agent.

[0028] In other words, preferably, most of the welded or embossed seam abuts the end face of the shrink cap. This further improves the mechanical stability and high-voltage resistance of the shrink cap.

[0029] Particularly preferably, the welded or embossed seam abuts the end face completely directly or indirectly through an intervening bonding agent.

[0030] Preferably, the welded or embossed seam is bent 90° and placed with one side abutting the end face of the shrink cap. Preferably, the welded or embossed seam does not protrude beyond the outer edge or outer circumference of the shrink cap. In this way, the maximum possible mechanical stability and high-voltage resistance are ensured. At the same time, the risk of injury and damage caused by the shrink cap is minimized.

[0031] In other improved embodiments, the formed part of the welded or embossed seam is pressed against the end face.

[0032] Preferably, this results in a seamless, substantially wrinkle-free welded or embossed seam being applied to the end face of the shrink cap. Preferably, the part or the entire welded or embossed seam is thermoformed or heat-formed by heating (whether from external hot air and / or a thermoforming die), and then pressed against the end face of the shrink cap. This results in a very compact shrink cap that includes a high level of stability and high pressure resistance, particularly in the region of the end face.

[0033] In other improvements, the formed part of the welded or embossed seam is fixed to the end face in a material-locking manner.

[0034] For example, after the welded or embossed seam has been produced and formed, the formed part of the welded or embossed seam is glued or welded to the end face of the shrink cap using the formed part. This ensures that the formed part of the welded or embossed seam remains permanently attached to the end face, as the formed part is additionally fixed to the end face.

[0035] In other improvements, the end face of the shrink cap is curved convexly. Particularly preferably, the end face is curved when viewed in the longitudinal section of the shrink cap.

[0036] This additionally minimizes the risk of injury and damage caused by the shrink cap. Furthermore, this shape is particularly suitable for receiving temperature-dependent switches, which are typically cylindrical or circular.

[0037] In other improvements, the formed part of the welded or embossed seam extends substantially parallel to the convexly curved end face.

[0038] Thus, the formed part of the welded or embossed seam clings to the front of the shrink cap, similar to a second wall. This also further improves the compactness, mechanical stability, high pressure resistance, and rigidity of the shrink cap.

[0039] In other improvements, the shrink cap in the region between the first end and the second end is substantially mirror-symmetrical with respect to a first symmetry plane, wherein the welded or embossed seam at its end adjacent to the end face is arranged offset from the first symmetry plane.

[0040] In other words, the welded or embossed seam is not produced in the center of the first symmetry plane of the heat-shrinkable tube section of the shrink cap, but is offset relative to this first symmetry plane. This has the advantage that the welded or embossed seam can be relatively large and, after the shrink cap has been bent and applied to the end face, still does not project laterally beyond the edge of the shrink cap. Even if the welded or embossed seam is placed completely against the end face of the shrink cap by one of its sides, the welded or embossed seam still does not project laterally (i.e., in a direction transverse to the first symmetry plane) beyond the end face. Thus, the usually sharp-edged free end of the welded or embossed seam does not project laterally from the end face of the shrink cap. Consequently, subsequent cutting or shortening of the welded or embossed seam can be omitted.

[0041] All of this can be achieved by arranging the welded or embossed seam offset or displaced, even if the welded or embossed seam has a relatively large surface area. The large-surface-area design of the welded or embossed seam increases the tightness of the seam and facilitates handling during the production of the welded or embossed seam.

[0042] Preferably, the joining surface in the end of the welded or embossed seam adjacent to the end face is offset parallel to the first symmetry plane.

[0043] The "joining surface" herein refers to the surface along which the two longitudinal halves of the heat-shrinkable tube are joined to each other, and the two longitudinal halves of the heat-shrinkable tube are pressed together and joined when the welded or embossed seam is produced. After the welded or embossed seam is produced, this joining surface or joining plane extends parallel to the first symmetry plane. However, since a part of the welded or embossed seam according to the invention is subsequently shaped and placed against the end face of the shrink cap, the above-defined parallel offset arrangement of the joining surface "only" refers to the end of the welded or embossed seam adjacent to the end face or the end arranged on the end face.

[0044] In other improvement schemes, the end face has a height measured orthogonally to the first symmetry plane, wherein the welded or embossed seam is arranged to be offset parallel to the first symmetry plane by at least 1 / 10 of the height, preferably at least 1 / 5 of the height, at its end adjacent to the end face.

[0045] This enables the welded or embossed seam to have a height measured orthogonally to the first symmetry plane in the state where it is applied to the end face, and the height is greater than half of the height of the end face, and thus still does not project laterally beyond the end face.

[0046] As described above, the above-described improvement solutions and the improvement solutions defined in the claims relate not only to the shrink cap itself, but also to a temperature-related switch having such a shrink cap. Similarly, these improvement solutions also relate to a method of manufacturing a shrink cap according to the present invention. In particular, this results in the following further improvement solutions of the manufacturing method according to the present invention:

[0047] In further improvement solutions, in step c), the portion of the welded or embossed seam is shaped such that more than 50% of the area on one side of the abutting end face of the welded or embossed seam directly abuts the end face or abuts the end face through an intervening bonding agent.

[0048] In further improvement solutions, in step c), the portion of the welded or embossed seam is shaped such that the welded or embossed seam directly and completely abuts the end face or completely abuts the end face through an intervening bonding agent.

[0049] In further improvement solutions, in step c) or after step c), the portion of the welded or embossed seam is pressed against the end face. Preferably, before or during this pressing process, the welded or embossed seam is heated so that the welded or embossed seam can be more easily formed.

[0050] In further improvement solutions, in step c) or after step c), the portion of the welded or embossed seam is fixed to the end face in a material-locking manner.

[0051] In further improvement solutions, in step c), the portion of the welded or embossed seam is shaped such that the shaped portion extends substantially parallel to the end face.

[0052] In further improvement solutions, in step b), the welded or embossed seam is produced offset parallel to the first symmetry plane of the shrink tube section.

[0053] In further improvement solutions, the welded or embossed seam produced in step b) is offset from the first symmetry plane of the shrink tube section such that the welded or embossed seam produced in step b) is substantially mirror-symmetrical with respect to a second symmetry plane, the second symmetry plane being offset parallel to the first symmetry plane.

[0054] In further improvement solutions, the welded or embossed seam produced in step b) is offset from the first symmetry plane of the shrink tube section such that the welded or embossed seam produced in step b) is substantially mirror-symmetrical with respect to a second symmetry plane, the second symmetry plane being offset from the first symmetry plane by at least 1 / 10 of the height measured orthogonally to the first symmetry plane, preferably offset by at least 1 / 5 of the height.

[0055] In further improvement solutions, in step c), the welded or embossed seam is shaped such that the free end of the welded or embossed seam does not project beyond the end face in a direction orthogonal to the first symmetry plane.

[0056] It should be understood that, without departing from the scope of the present invention, the above features and the features to be explained below can be used not only in the combinations indicated in each case, but also in other combinations or individually. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Embodiments of the present invention are shown in the drawings and are explained in more detail in the following description. The drawings show:

[0058] Figure 1 Schematic views of several views of a shrink cap of the prior art;

[0059] Figure 2A A side view of a shrink cap according to a first embodiment of the present invention;

[0060] Figure 2B is Figure 2A A cross-sectional view of the shown shrink cap;

[0061] Figure 3A A side view of a shrink cap according to a second embodiment of the present invention;

[0062] Figure 3B is Figure 3A A cross-sectional view of the shown shrink cap;

[0063] Figure 4 A side view of a shrink cap according to a third embodiment and a top view from the front of the self-shrinking cap, where the shrink cap is shown here in an intermediate state occurring during the production process;

[0064] Figure 5A A side view of a shrink cap according to a third embodiment, where the shrink cap is shown here in its final completed state;

[0065] Figure 5B is Figure 5A A cross-sectional view of the shown shrink cap; and

[0066] Figure 6 Schematically shows several process steps for manufacturing a shrink cap according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0067] Figure 1 Shrink caps according to the prior art are shown in various schematic views. The shrink cap as a whole is denoted by the reference numeral 10.

[0068] Figure 1The shrink cap 10 shown can also be regarded as an intermediate state during the manufacturing process of the shrink cap 10 according to the present invention. In other words, the shrink cap 10 according to the present invention (which will be explained in more detail hereinafter) is initially produced in a conventional manner, but is further processed in a different way compared to shrink caps previously known from the prior art.

[0069] In particular, the shrink cap 10 is used to receive a temperature-dependent switch 12, the external connection 14 of which is shown in a simplified form herein as a stranded wire. Such a temperature-dependent switch 12 is used to monitor an electrical device. In particular, they are used to cut off the power supply of the electrical device to be monitored in case of overheating. For this purpose, the switch 12 includes a temperature-dependent switching mechanism, which is usually installed inside the switch housing and includes a bimetallic part. This bimetallic part changes its shape when the response temperature is exceeded, whereby the switching mechanism moves from its closed position to its open position. Then, the circuit in which the switch 12 is installed is disconnected. If the device to be monitored cools down again below the so-called reset temperature of the bimetallic part, this will in turn cause the bimetallic part to quickly return to its initial position, thus causing the switch to return to its closed position. In this way, the temperature-dependent switching behavior of the switch 12 is achieved.

[0070] In particular, the shrink cap 10 according to the present invention is used to provide external protection and electrical shielding for the switch 12. The shrink cap 10 is placed on the switch 12 and attached to or shrunk onto the switch 12 such that the shrink cap 10 surrounds the switch 12 on all sides in the final state.

[0071] However, it should be understood that the shrink cap 10 according to the present invention is also suitable in principle for receiving other devices and is not limited to receiving a temperature-dependent switch as shown in this example.

[0072] The cross-section of the shrink cap 10 is as shown in 16. The shrink cap 10 is slid onto the switch 12 using the first end 18 of the shrink cap 10 and then shrunk onto the switch using hot air such that only the external connection 14 protrudes from the resulting sheath. Therefore, the first end 18 is configured as an open end including a first opening 19.

[0073] The second end 20 of the shrink cap 10 opposite the first end 18 is closed. Herein, the shrink cap 10 includes a welded or embossed seam 22 provided in the region of the second end 20. Through this welded or embossed seam 22, the shrink cap 10 is completely closed in the region of its second end 20. Due to the welded or embossed seam 22, the shrink cap 10 includes a closed end face 24 in the region of its second end 20, which closed end face 24 is adjacent to the welded or embossed seam 22.

[0074] Due to manufacturing processes, the welded or embossed seam 22 is configured as a pleat or edge that projects straight out from the end face 24 of the shrink cap 10. This pleat or edge is relatively rigid or non-flexible and includes a relatively sharp edge 28 at its free end 26 at the front.

[0075] When viewed from above, the free front edge 28 on the front face of the welded or embossed seam 22 is curved into an arcuate shape (see Figure 1 the upper middle part). This is also due to manufacturing processes, since the shrink cap 10 (as will be explained in detail below) is produced in the region of its second end 20 by pressing together the initially still open ends (opening 21) of a cylindrical shrink tube and then welding or embossing to produce the welded or embossed seam 22.

[0076] At 16, the cross-section of the shrink cap 10 is shown as elliptical or oval. However, when viewed in cross-section, the shrink cap 10 can also be approximately circular. The cross-section of the starting material in the form of a heat-shrink tube for the shrink cap 10 is usually round or circular, i.e., cylindrical overall.

[0077] The end face 24 of the shrink cap 10 formed by the welded or embossed seam 22 is configured to be convex, as can be seen especially from Figure 1 the top view from above in the upper middle part of Figure 1 and the side view in the lower part of

[0078] Figure 1 It should be understood that the shape of the end face 24 shown herein is schematically illustrated. In practice, this end face 24 is usually curved into a convex shape, but is usually not as completely circular and regular as shown in this figure. However, due to manufacturing processes, as described above, this arcuate roundness or curvature of the end face 24 is produced. Depending on the shape of the switch 12 onto which the shrink cap 10 is to be shrunk, the end face 24 can also be angled or substantially flat, and the welded or embossed seam 22 can extend along a straight line. However, a circular or curved welded or embossed seam 22 is advantageous for receiving a switch 12 that is mainly circular. Figure 1 The state of the shrink cap 10 after the welded or embossed seam 22 has been produced is shown. This state corresponds to the final state of the vast majority of shrink caps in the prior art for encapsulating temperature-related switches. In this state, the shrink cap 10 is substantially mirror-symmetrical with respect to a first symmetry plane, which is denoted by the reference numeral 30 in

[0079] If the shrink cap 10 used in the prior art is used in the state shown in Figure 1 and is not further processed, due to the relatively sharp edges 28 at the end face 26 of the welded or embossed seam 22, there is a relatively high risk of injury to personnel, as well as a risk of damage to the components of the machine on which the temperature-related switch 12 and its shrink cap 10 are installed.

[0080] Therefore, according to the present invention, the shrink cap 10 is further processed starting from the Figure 1 shown intermediate state. Herein, the welded or embossed seam 22 is formed such that at least the formed part 32 of the welded or embossed seam 22 contacts the end face 24 of the shrink cap 10. In other words, the welded or embossed seam 22 is bent by about 90° or a slightly larger angle and is placed at least partially against the end face 24. The formed part 32 of the welded or embossed seam 22 placed against the end face 24 of the shrink cap 10 abuts directly or indirectly against the end face 24 through an intervening bonding agent.

[0081] In Figure 2A , Figure 2B , Figure 3A and Figure 3B , the final completed states of two different embodiments of the shrink cap 10 according to the present invention are shown. Figure 2A and Figure 3A each show the shrink cap 10 in a side view. Figure 2B and Figure 3B each show the shrink cap 10 in a longitudinal cross-sectional view. In each case, the cross-section is perpendicular to the first symmetry plane 30 represented by the dashed line in Figure 1 .

[0082] As can be seen from FIGS. 2 and 3, the shrink cap 10 according to the present invention, now in its final state, is no longer mirror-symmetrical about the first symmetry plane 30 as a whole. However, the left part of the shrink cap 10 is still substantially mirror-symmetrical about the first symmetry plane 30. In other words, except for the welded or embossed seam 22, the completed shrink cap 10 is substantially mirror-symmetrical about the first symmetry plane 30.

[0083] In Figure 2A and Figure 2BIn the first embodiment shown, the welded or embossed seam 22 is folded and partially glued to the end face 24 of the shrink cap 10. In the region of the end 34 of the welded or embossed seam 22 adjacent to the end face 24, a smaller bead can be produced by folding the welded or embossed seam 22, which projects slightly forward from the end face 24. However, generally, by folding the welded or embossed seam 22 and placing it against the end face 24, the effective length of the shrink cap 10 is significantly shortened. In addition, the sharp edge 28 of the welded or embossed seam 22 no longer projects from the front of the shrink cap 10. Therefore, the risk of injury and damage is greatly reduced. In addition, in the region of the folded welded or embossed seam 22, the shrink cap 10 has improved high-pressure resistance, because the welded or embossed seam 22 forms another layer in this part 32, and it can be said that through this another layer, the wall thickness of the shrink cap increases, and thus the high-pressure resistance of the shrink cap also increases.

[0084] In Figure 3A and Figure 3B the second embodiment shown, the welded or embossed seam 22 is applied to the end face 24 of the shrink cap almost completely or at least in a larger part than according to the first embodiment (see Figure 2A and Figure 2B ). Preferably, the welded or embossed seam 22 is pressed against the end face 24. This preferably produces a seamless and substantially wrinkle-free welded or embossed seam 22 applied to the end face 24 of the shrink cap 10. The forming of the welded or embossed seam 22 of this type is preferably carried out under the action of heat, as will be explained in detail below.

[0085] According to the intended use, it is preferred that the part 32 of the welded or embossed seam 22 applied to the end face 24 can be applied to the end face loosely or connected to the end face by an additional welding or bonding process.

[0086] Particularly preferably, according to Figure 3A and Figure 3B the second embodiment shown, the formed part 32 of the welded or embossed seam 22 causes at least most of the bottom side 36 (i.e., by more than 50% of the area) to rest on the end face 24, and at least most of the bottom side 36 is folded onto the end face 24.

[0087] Since in Figure 1 the initial state shown, the welded or embossed seam 22 can project far from the end face 24 according to its size, folding and positioning the welded or embossed seam 22 can cause the welded or embossed seam 22 to project downward or laterally from the shrink cap 10, as can be seen from Figure 3BIt can be seen specifically. In order to completely avoid the risk of damage and / or injury, it is advantageous to cut the welded or embossed seam 22 to a certain length, or to cut off the welded or embossed seam 22 in the region of the end face 26 of the welded or embossed seam 22. However, this may have the disadvantage of causing leakage, which can damage the complete enclosure of the shrink cap 10 in the region of the second end 20. For example, cracks or holes may occur in the welded or embossed seam 22, and impurities may enter the interior of the shrink cap 10 through the cracks or holes. It goes without saying that this is a fundamental disadvantage.

[0088] According to Figure 4 、 Figure 5A and Figure 5B In the third embodiment of the shrink cap 10 shown, the welded or embossed seam 22 can be arranged to be offset parallel to the first symmetry plane 30 described above. In other words, the welded or embossed seam 22 is not produced at the center of the shrink cap 10, but is highly offset relative to the symmetry plane 30. Figure 4 Fig. shows an intermediate state of the shrink cap 10 after the welded or embossed seam 22 has been produced (before the welded or embossed seam 22 is formed). In this state, the shrink cap 10 according to the third embodiment is thus substantially mirror-symmetrical with respect to the first symmetry plane 30 only in the region between the first end 18 and the second end 20. Due to the offset arrangement of the welded or embossed seam 22, the shrink cap 10 is not substantially mirror-symmetrical with respect to the first symmetry plane 30 as a whole.

[0089] Figure 4 The right side of shows a top view of the shrink cap 10 passing through the first opening 19 from the front. Here, the welded or embossed seam 22 can be regarded as a line offset parallel to the first symmetry plane 30. This line is formed by the joining surface 68 along which the two longitudinal halves of the heat-shrinkable tube are joined, and the two longitudinal halves of the heat-shrinkable tube are pressed together and joined when the welded or embossed seam 22 is produced. When the welded or embossed seam 22 is produced according to the third embodiment schematically shown in Figure 4 , this joining surface 68 extends parallel to the first symmetry plane 30. In other words, the joining surface 68 lies in the second symmetry plane 70, the welded or embossed seam 22 is substantially mirror-symmetrical with respect to the second symmetry plane 70, and the second symmetry plane 70 is parallel to the first symmetry plane 30.

[0090] If starting from the intermediate state shown in Figure 4 , the welded or embossed seam 22 is now formed, and is either only partially applied to the end face 24 according to the first embodiment, or is completely applied according to the second embodiment, then the sharp edge 28 of the welded or embossed seam 22 no longer protrudes laterally or downward from the shrink cap 10 (see Figure 5A and Figure 5B) No further rework is required, such as shortening the welded or embossed seam. The risk of injury or damage is minimized.

[0091] In Figure 5A and Figure 5B In the final state of the shrink cap 10 shown, the welded or embossed seam 22 is indeed fully or nearly fully folded. However, it should be understood that the end or starting portion 34 of the welded or embossed seam 22 adjacent to the end face 24 remains offset parallel to the first symmetry plane 30 as described. Thus, this end or starting portion 34 particularly represents the inner boundary line of the welded or embossed seam 22, at which the welded or embossed seam 22 starts, or into which the welded or embossed seam merges into the end face 24 of the shrink cap 10.

[0092] According to Figure 4 、 Figure 5A and Figure 5B In the third embodiment shown, the end portion 34 of the welded or embossed seam 22 adjacent to the end face 24 is preferably offset from the first symmetry plane 30 by a height h 1 of at least 1 / 10, further preferably offset by a height h 1 of at least 1 / 5, particularly preferably offset by more than 1 / 3 of the height h 1 The height h 1 represents the dimension of the shrink cap 10 measured orthogonally to the first symmetry plane 30 in the region of the first end 18. The offset is indicated by the reference numeral X in the right - hand portion of Figure 4 .

[0093] Figure 6 Schematically illustrates a method of producing the shrink cap 10 according to the invention from a heat - shrinkable tube 38.

[0094] First, a shorter heat - shrinkable tube section 40 is cut from the heat - shrinkable tube 38. The heat - shrinkable tube section 40 has opposite open ends 18, 20, and each open end includes an opening 19, 21. Then, these heat - shrinkable tube sections 40 are slid one by one onto a forming part 42 located on a turntable 44.

[0095] After being pushed onto the forming part 42, the turntable 44 rotates 90° in the direction of the arrow 46 shown in Figure 6 (here clockwise), so that the corresponding heat - shrinkable tube section 40 reaches the welding position 48.

[0096] At the welding position 48, the heat - shrinkable tube section 40 is heated and pre - formed by hot air represented by 50, where two welding dies 52 act simultaneously on the second end 20 of the heat - shrinkable tube section 40. This closes the second opening 21 of the heat - shrinkable tube section 40 and produces the welded or embossed seam 22.

[0097] Figure 6 One of the two welding stamps 52 is schematically shown therein. At 54, the position where the welding stamp 52 engages with the heat-shrinkable tube section 40 is also shown. Generally, the welding stamps 52 emerge from above and below, thereby pressing the ends of the heat-shrinkable tube together, where a welded or embossed seam 22 as shown in Figure 1 or Figure 4 is produced by heating.

[0098] The shrink cap 10 now has the intermediate state as shown in Figure 1 or Figure 4 .

[0099] The turntable 44 now rotates another 90° in the direction of arrow 46, such that the shrink cap 10 reaches the forming position 56. Here, the welded or embossed seam 22 is preferably reheated by hot air 58 in order to make the welded or embossed seam 22 easier to form. At the same time, the forming or extrusion punch 60 presses against the welded or embossed seam 22 from the front, in order to bend the welded or embossed seam 22 and apply or extrude the welded or embossed seam 22 against the end face 24 of the shrink cap 10.

[0100] At Figure 6 's right side, the forming or extrusion punch 60 is schematically shown in a top view and a side view, wherein the side view includes a heater 62, which can be used instead of the hot air 58 to heat the welded or embossed seam 22 with high accuracy before or during forming.

[0101] The forming or extrusion punch 60 includes a forming area 64, which has an arcuate side surface and is preferably adapted to the curvature of the end face 24 of the shrink cap 10.

[0102] As described above, in this process step, the welded or embossed seam 22 can additionally be connected to the end face 24, i.e., the welded or embossed seam 22 can additionally be welded or glued to the end face 24. Alternatively, the welded or embossed seam 22 is "merely" applied or extruded against the end face 24.

[0103] Finally, the turntable 44 rotates another 90° in the direction of arrow 46, such that the completed shrink cap 10 reaches the ejection position 66 and is ejected, for example, by compressed air. Then, the shrink cap 10 produced in this way can be stored, for example, as bulk material until it is used for encapsulating a temperature-related switch.

[0104] It should be understood that these drawings only schematically represent the shrink cap 10 and its manufacture, and various other geometric or manufacturing modifications can be made without departing from the scope of the present invention defined by the appended claims.

Claims

1. A shrink cap (10) configured to receive a temperature-dependent switch (12) and comprising an open first end (18) and a second end (20) closed by a welded or embossed seam (22) extending from a closed end face (24), wherein the closed end face (24) is produced by the welded or embossed seam (22), in, The welded or embossed seam (22) is shaped so that a shaped portion (32) of the welded or embossed seam (22) abuts against the end face (24) directly or by a bonding agent interposed between the welded or embossed seam (22) and the end face (24).

2. The shrink cap according to claim 1, wherein: The welded or embossed seam (22) comprises a free end (26) and an end (34) adjoining the end face (24), wherein the shaped portion (32) of the welded or embossed seam (22) abutting against the end face (24) directly or via the intervening bonding agent extends over the area between the free end (26) and the end (34).

3. The shrink cap according to claim 1, wherein: More than 50% of the area of ​​the side (36) of the welded or embossed seam (22) that abuts against the end surface (24) abuts against the end surface (24) directly or through the intervening bonding agent.

4. The shrink cap according to claim 1, wherein: The welded or embossed seam (22) bears against the end face (24) directly or with the intervening bonding agent.

5. The shrink cap according to claim 1, wherein: The shaped portion (32) of the welded or embossed seam (22) is pressed against the end face (24).

6. The shrink cap according to claim 1, wherein: The shaped portion (32) of the welded or embossed seam (22) is fixed to the end face (24) in a material-locking manner.

7. The shrink cap according to claim 1, wherein: The end surface (24) is curved into a convex shape.

8. The shrink cap according to claim 7, wherein: The shaped portion (32) of the welded or embossed seam (22) extends parallel to the convexly curved end surface (24).

9. The shrink cap according to claim 1, wherein: The shrink cap (10) in the region between the first end (18) and the second end (20) is substantially mirror-symmetrical with respect to a first plane of symmetry (30), and wherein the welded or embossed seam (22) at the end (34) adjoining the end face (24) is arranged offset parallel to the first plane of symmetry (30).

10. The shrink cap according to claim 9, wherein: The joining surface (68) of the welded or embossed seam (22) in the end (34) of the welded or embossed seam (22) adjacent to the end surface (24) is offset parallel to the first plane of symmetry (30).

11. The shrink cap according to claim 9, wherein: The end face (24) has a height (h1) measured orthogonally to the first symmetry plane (30), and wherein the welded or embossed seam (22) is arranged offset parallel to the first symmetry plane (30) by at least 1 / 10 of the height (h1) at its end (34) adjacent to the end face (24).

12. The shrink cap according to claim 11, wherein: The height (h2) of the welded or embossed seam (22) measured orthogonally to the first symmetry plane (30) is greater than half the height (h1) of the end surface (24), and the height (h2) is measured from the end (34) of the welded or embossed seam (22) adjacent to the end surface (24) to the free end (26) of the welded or embossed seam (22).

13. A temperature-dependent switch (12) comprising a shrink cap (10) according to any one of claims 1 to 12.

14. A method of manufacturing a shrink cap (10), the method comprising: a) providing a heat shrink tubing section (40) comprising a first opening (19) at a first end (18) and a second opening (21) at a second end (20); b) pressing the heat shrink tubing sections (40) together at their second ends (20) and producing a welded or embossed seam (22) to close the second opening (21) and to form a closed end face (24) in the region of the second end (20), and c) shaping a portion (32) of the welded or embossed seam (22) such that the shaped portion (32) of the welded or embossed seam (22) abuts against the end face (24) directly or via an intervening bonding agent.

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