Shrink cap and method of making shrink cap

Abstract

A collapsible cap (10) for sliding onto 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). In a region between the first end (18) and the end face (24), the shrink cap (10) is substantially mirror-symmetric with respect to the first plane of symmetry (30). The welded or embossed seam (22) is arranged parallel to the first plane of symmetry (30) at its end (34) adjacent the end face (24).

Description

Field of the Invention

[0001] The present invention relates to a shrink cap and a method for 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] EP 0 857 562 B1 discloses a general shrink cap and a general method for manufacturing such a shrink cap.

[0003] Such shrink caps are usually in bulk 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 usually configured as stranded wires or cables and then protrude from the sheath.

[0004] Such shrink caps are usually 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 end 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 usually 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, and the closed end face is respectively formed by the welded or embossed seam on the heat-shrinkable tube or the shrink cap. 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 still exist.

[0007] Many process steps are usually 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 operation repeatedly causes injuries to 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 the devices made from these components typically 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 EP 0 857 562 B1, 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 upright from the front of the shrink cap.

[0013] This measure effectively prevents the above-mentioned problem of personnel injuries 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, as described in EP 0 857 562 B1, whose weld or embossed seams are bent by 90° or more 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, the 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-related switch, wherein the shrink cap comprises an open first end for sliding onto the switch and a closed second end closed by a welded or embossed seam, said welded or embossed seam extending from a closed end face arranged in the region of the second end and produced by the welded or embossed seam, wherein the shrink cap is substantially mirror-symmetrical with respect to a first symmetry plane in the region between the first end and the end face, and wherein the welded or embossed seam is arranged to be offset parallel to the first symmetry plane at the end adjacent to the end face.

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

[0018] a) Providing a shrink tube section, said shrink tube section comprising a first opening at its first end and a second opening at its second end, and said shrink tube section being substantially mirror-symmetrical with respect to a first symmetry plane,

[0019] b) Squeezing together the heat-shrinkable tube section at the second end thereof and producing a welded or embossed seam to close the second opening and form a closed end face adjacent to the welded or embossed seam in the region of the second end, wherein the welded or embossed seam is produced to be offset parallel to the first symmetry plane,

[0020] c) Shaping a part of the welded or embossed seam such that at least a part of the welded or embossed seam is bent.

[0021] In other words, the welded or embossed seam is not produced at the center of the first symmetry plane of the heat-shrinkable tube section for manufacturing the shrink cap, but is offset with respect to the first symmetry plane.

[0022] This has the advantage that the welded or embossed seam can be relatively large and, after shaping, still does not project laterally beyond the edge of the shrink cap. Preferably, the welded or embossed seam is not folded or rolled up, but is only bent in one direction. Due to the offset of the welded or embossed seam, there is a relatively large space into which the welded or embossed seam can be bent. For example, if the welded or embossed seam is provided on an end face offset upward parallel to the first symmetry plane, there is a relatively large space below the welded or embossed seam into which the welded or embossed seam can be bent.

[0023] Even if the welded or embossed seam is bent exactly 90° and is longer than half of the height of the shrink cap, the welded or embossed seam still does not project laterally (i.e., in a direction transverse to the first symmetry plane) from the shrink cap. In particular, the usually sharp-edged free end of the welded or embossed seam does not project laterally from the shrink cap. Thus, subsequent cutting or shortening of the welded or embossed seam can be omitted.

[0024] All of these can be achieved by arranging the welded or embossed seam off - center or offset, even if the welded or embossed seam has a relatively large surface area. The large - 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.

[0025] Therefore, the above - mentioned object is completely solved.

[0026] In an improved embodiment, the joint surface in the end of the welded or embossed seam adjacent to the end face is offset parallel to the first symmetry plane.

[0027] The "joint surface" herein refers to the surface along which the two longitudinal halves of the heat - shrinkable tube are connected to each other, and the two longitudinal halves of the heat - shrinkable tube are squeezed together and joined when the welded or embossed seam is produced.

[0028] After the welded or embossed seam is formed, the joint surface or joint plane extends parallel to the first symmetry plane. However, since a part of the welded or embossed seam according to the present invention is subsequently shaped, the above - defined parallel offset arrangement of the joint 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.

[0029] In other improved embodiments, the joint surface inside the shrink - cap defines a boundary line, which is curved in an arc shape.

[0030] This boundary line is the start of the joint surface, which is visible from the inside, i.e., as seen through the first opening.

[0031] In other improved embodiments, 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 at least 1 / 10 of the height, preferably at least 1 / 5 of the height, at its end adjacent to the end face.

[0032] Particularly preferably, the height of the welded or embossed seam measured orthogonally to the first symmetry plane is greater than half of the height of the end face, and the height is measured from the end of the welded or embossed seam adjacent to the end face to the free end of the welded or embossed seam.

[0033] This enables the welded or embossed seam to have a height measured orthogonally to the first symmetry plane greater than half of the height of the end face in its final formed state, so that it still does not protrude laterally beyond the end face.

[0034] In other improved embodiments, the welded or embossed seam is shaped such that the shaped part of the welded or embossed seam directly abuts against the end face or abuts against the end face through an intervening bonding agent.

[0035] Thus, compared to that proposed in EP 0 857 562 B1, the welded or embossed seam is not only bent, folded or rolled 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 approximately 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 via an intervening bonding agent against the end face of the shrink cap.

[0036] This has several advantages: Firstly, the shrink cap and thus also the device to which the shrink cap is applied (e.g., a temperature-dependent switch) are further shortened. This smaller size is advantageous both in terms of bulk storage of the shrink caps and in terms of handling and installation options for the shrink caps. Additionally, it has been shown that by applying the welded or embossed seam to the end face of the shrink cap, the risk of damage and injury is further reduced, since the sharp edges of the welded or embossed seam can be fully applied to the end face of the shrink cap such that the said sharp edges no longer protrude from the shrink cap at all and are thus hardly accessible. Furthermore, it has been shown that this creates a double or multi-layer wall at this end of the shrink cap, since the welded or embossed seam abutting 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 caps according to the invention can achieve a high-voltage resistance of 3.5 kV or more.

[0037] In an improved embodiment, the welded or embossed seam comprises a free end and an end adjacent to the end face, wherein the shaped part of the welded or embossed seam that abuts directly against the end face or via an intervening bonding agent against the end face extends over the region between the free end and the end adjacent to the end face.

[0038] Thus, preferably, the welded or embossed seam contacts the end face of the shrink cap at least via a central part extending between the free end and the end adjacent to the end face.

[0039] In other improved embodiments, preferably, more than 50% of the area of the side of the welded or embossed seam abutting against the end face abuts directly against the end face or via an intervening bonding agent against the end face.

[0040] In other words, preferably, most of the welded or embossed seam abuts against the end face of the shrink cap. This further improves the mechanical stability and high-voltage resistance of the shrink cap.

[0041] Particularly preferably, the welded or embossed seam abuts completely against the end face directly or indirectly via an intervening bonding agent.

[0042] Preferably, the welded or embossed seam is bent by 90° and one side is placed against 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-pressure resistance are ensured. At the same time, the risk of injury and damage caused by the shrink cap is minimized.

[0043] In other improvement solutions, the formed part of the welded or embossed seam is pressed against the end face.

[0044] Preferably, this results in a seamless and substantially wrinkle-free welded or embossed seam applied to the end face of the shrink cap. Preferably, the part or the whole of the welded or embossed seam is thermoformed or heat-formed by heating (either hot air from the outside 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, especially in the area of the end face.

[0045] In other improvement solutions, the formed part of the welded or embossed seam is fixed to the end face in a material-locking manner.

[0046] For example, after the welded or embossed seam has been produced and formed, 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 because the formed part is additionally fixed to the end face.

[0047] In other improvement solutions, the end face of the shrink cap is curved convexly. Particularly preferably, when viewed from the longitudinal section of the shrink cap, the end face is curved.

[0048] This additionally minimizes the risk of injury and damage caused by the shrink cap. In addition, this shape is particularly suitable for receiving temperature-related switches, which are usually cylindrical or circular.

[0049] In other improvement solutions, the formed part of the welded or embossed seam extends substantially parallel to the convexly curved end face.

[0050] Therefore, the formed part of the welded or embossed seam closely adheres to the front part 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.

[0051] As described above, the above improvement solutions and the improvement solutions defined in the claims not only relate to the shrink cap itself, but also to temperature-related switches having such a shrink cap. Similarly, these improvement solutions also relate to methods for manufacturing shrink caps according to the present invention. In particular, this results in the following additional improvement solutions for the manufacturing method according to the present invention:

[0052] In an improved embodiment, 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.

[0053] In other improved embodiments, 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 by at least 1 / 5 of the height.

[0054] In other improved embodiments, in step c), a portion of the welded or embossed seam is shaped such that the shaped portion of the welded or embossed seam abuts directly against the end face or abuts against the end face through an intervening bonding agent.

[0055] In other improved embodiments, the welded or embossed seam includes a free end and an end adjacent to the end face, wherein the shaped portion of the welded or embossed seam that abuts directly against the end face or abuts against the end face through an intervening bonding agent extends over an area between the free end and the end adjacent to the end face.

[0056] In other improved embodiments, in step c), a portion of the welded or embossed seam is shaped such that more than 50% of the area on the side of the welded or embossed seam that abuts against the end face abuts directly against the end face or abuts against the end face through an intervening bonding agent.

[0057] In other improved embodiments, in step c), a portion of the welded or embossed seam is shaped such that the welded or embossed seam abuts directly and completely against the end face or abuts completely against the end face through an intervening bonding agent.

[0058] In other improved embodiments, in step c) or after step c), a portion of the welded or embossed seam is pressed against the end face.

[0059] In other improved embodiments, in step c) or after step c), a portion of the welded or embossed seam is fixed to the end face in a material-locking manner.

[0060] In other improved embodiments, the end face is curved convexly.

[0061] In other improved embodiments, in step c), a portion of the welded or embossed seam is shaped such that the shaped portion extends substantially parallel to the end face curved convexly.

[0062] In other improved embodiments, 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.

[0063] 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

[0064] Embodiments of the present invention are shown in the drawings and are explained in more detail in the following description. The drawings show:

[0065] Figure 1 is a schematic view in several views of an intermediate state during production of a shrink cap according to the present invention;

[0066] Figure 2A is a side view of a shrink cap according to a first embodiment of the present invention;

[0067] Figure 2B is Figure 2A a cross-sectional view of the shrink cap shown;

[0068] Figure 3A is a side view of a shrink cap according to a second embodiment of the present invention;

[0069] Figure 3B is Figure 3A a cross-sectional view of the shrink cap shown;

[0070] Figure 4 Schematically shows several process steps for manufacturing a shrink cap according to the present invention. DETAILED DESCRIPTION

[0071] Figure 1 Intermediate states achieved during the manufacture of a shrink cap according to the present invention are shown in various schematic views. The shrink cap is generally designated by the reference numeral 10 in the drawings.

[0072] In particular, the shrink cap 10 is intended to receive a temperature-dependent switch 12, the external connection 14 of which is shown herein in simplified form as a stranded wire. Such temperature-dependent switches 12 are used to monitor electrical equipment. In particular, they are used to switch off the electrical equipment to be monitored in the event of overheating. For this purpose, the switch 12 includes a temperature-dependent switching mechanism which is usually installed inside a 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 equipment to be monitored cools down again below the so-called reset temperature of the bimetallic part, this in turn causes 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.

[0073] 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 in the final state, the shrink cap 10 surrounds the switch 12 on all sides.

[0074] 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 temperature-related switches as shown in this example.

[0075] 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. Thus, the first end 18 is configured as an open end including a first opening 19.

[0076] The second end 20 of the shrink cap 10 opposite the first end 18 is closed. Here, 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, and the closed end face 24 is adjacent to the welded or embossed seam 22.

[0077] Due to manufacturing processes, the welded or embossed seam 22 is configured as a fold or edge protruding straight from the end face 24 of the shrink cap 10. This fold or edge is relatively rigid or non-flexible and includes a relatively sharp edge 28 at its free end 26 at the front.

[0078] Figure 1 The state of the shrink cap 10 after the formation of the welded or embossed seam 22 (before the welded or embossed seam 22 is formed) is shown. In this state, the shrink cap 10 is substantially mirror-symmetrical with respect to a first symmetry plane 30 in the region between the first end 18 and the second end 20. Preferably, the shrink cap 10 is substantially mirror-symmetrical with respect to this first symmetry plane 30 except for the welded or embossed seam 22. In this case, the phrase "substantially mirror-symmetrical" is used to mean that in practice there is usually no absolutely precise mirror symmetry. However, in principle, this mirror symmetry does exist, and the minor deviations (usually in the range of millimeters or tenths) that occur in practice due to manufacturing processes can be ignored.

[0079] However, the shrink cap 10 is not substantially mirror-symmetrical with respect to the first symmetry plane 30 overall. The welded or embossed seam 22 is arranged offset parallel to this first symmetry plane 30. More specifically, in Figure 1In the state shown, the welded or embossed seam 22 is substantially mirror-symmetrical with respect to a second symmetry plane 70, which is parallel to and spaced apart from the first symmetry plane 30.

[0080] In other words, the welded or embossed seam 22 does not occur at the center of the shrink cap 10, but is highly offset with respect to the symmetry plane 30.

[0081] Figure 1 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. 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, the joining surface 68 extends parallel to the first symmetry plane 30. 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.

[0082] When viewed from above, the free front edge 28 of the front side of the welded or embossed seam 22 is curved in an arcuate shape (see Figure 1 the upper middle part of ). This is also due to the manufacturing process, 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.

[0083] 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-shrinkable tube for the shrink cap 10 is usually circular or round, i.e., cylindrical overall.

[0084] 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 in particular from Figure 1 the top view from above in the upper middle part of and Figure 1It can be seen from the side view of the lower part of []. It should be understood that the shape of the end face 24 shown herein is schematically shown. In practice, the end face 24 is usually curved convexly, but usually not completely circular and regular as shown in this figure. However, due to the manufacturing process, as described above, such an arc roundness or curvature of the end face 24 is produced. Depending on the shape of the switch 12 onto which the shrinkage 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 substantially circular switch 12.

[0085] The shrinkage cap 10 is used in the Figure 1 shown state and without further processing, there will be a relatively high risk of injury to personnel due to the relatively sharp edge 28 at the end face 26 of the welded or embossed seam 22, as well as a risk of damage to the components of the machine on which the temperature-related switch 12 and its shrinkage cap 10 are installed.

[0086] Therefore, according to the present invention, the shrinkage cap 10 is further processed starting from the Figure 1 shown intermediate state. Herein, the welded or embossed seam 22 can be formed such that at least the formed part 32 of the welded or embossed seam 22 contacts the end face 24 of the shrinkage cap 10. In other words, the welded or embossed seam 22 can be bent by about 90° or a slightly larger angle and 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 shrinkage cap 10 can directly or indirectly against the end face 24 through an intervening bonding agent. In principle, it is advantageous to rest against the end face 24, but it is not absolutely necessary according to the present invention. For example, the welded or embossed seam 22 can also be "only" bent by 90° without being applied to the end face 24 of the shrinkage cap 10 (i.e., not in contact with the end face 24 of the shrinkage cap 10).

[0087] If starting from the Figure 1 shown intermediate state, the welded or embossed seam 22 is bent by 90° and / or is partially or completely applied to the end face 24, then the sharp edge 28 of the welded or embossed seam 22 will no longer project laterally or downward from the shrinkage cap 10 due to the upwardly offset welded or embossed seam 22 (see Figure 3A and Figure 3B ). In addition, no further rework is required, such as shortening the welded or embossed seam. The risk of injury or damage is reduced to a minimum.

[0088] In Figure 2A , Figure 2B , Figure 3A and Figure 3BIn it, 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 shows the shrink cap 10 in a side view. Figure 2B And Figure 3B Each shows 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 In it.

[0089] In Figure 2A And Figure 2B In 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, and the bead 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 the other layer, the wall thickness of the shrink cap increases, so the high-pressure resistance of the shrink cap also increases.

[0090] In Figure 3A And Figure 3B In 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.

[0091] According to the intended use, preferably, 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.

[0092] Particularly preferably, according to Figure 3A And Figure 3B In 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., more than 50% of the area) to rest against the end face 24, and at least most of the bottom side 36 is folded onto the end face 24.

[0093] However, in principle, the welded or embossed seam 22 does not necessarily have to contact the end face 24, but can also be bent downwards by 90° or less, without touching the end face 24.

[0094] The end 34 of the welded or embossed seam 22 adjacent to the end face 24 is preferably offset by a height h from the first symmetry plane 30 1 by at least 1 / 10, further preferably by at least 1 / 5, particularly preferably 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. In 1 it, the offset is denoted by the reference sign X. Figure 1 In

[0095] Figure 4 schematically illustrates a method of producing the shrink cap 10 according to the invention from a heat - shrinkable tube 38.

[0096] First, a shorter heat - shrinkable tube section 40 is cut from the heat - shrinkable tube 38, the heat - shrinkable tube section 40 having opposite open ends 18, 20, each open end including 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.

[0097] After being pushed onto the forming part 42, the turntable 44 rotates 90° in the direction of the arrow 46 (here clockwise) as shown in Figure 4 so that the corresponding heat - shrinkable tube section 40 reaches the welding position 48.

[0098] At the welding position 48, the heat - shrinkable tube section 40 is heated and pre - formed by hot air denoted by 50, where two welding dies 52 act on the second end 20 of the heat - shrinkable tube section 40 simultaneously. This closes the second opening 21 of the heat - shrinkable tube section 40 and produces the welded or embossed seam 22.

[0099] Figure 4 One of the two welding dies 52 is schematically shown in. At 54, the position where the welding die 52 engages with the heat - shrinkable tube section 40 is also shown. Generally, the welding die 52 appears from above and below, thus 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.

[0100] The shrink cap 10 now has the intermediate state as shown in Figure 1 .

[0101] The turntable 44 now rotates another 90° in the direction of arrow 46 so 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 pressing punch 60 presses against the welded or embossed seam 22 from the front in order to bend the welded or embossed seam 22 and, if necessary, to apply or press the welded or embossed seam 22 against the end face 24 of the shrink cap 10.

[0102] On the Figure 4 right side of which is schematically shown in a top view and a side view the forming or pressing punch 60, wherein the side view includes a heater 62 which can be used instead of the hot air 58 for heating the welded or embossed seam 22 with high accuracy before or during forming.

[0103] The forming or pressing punch 60 includes a forming area 64 which has an arcuate side face and is preferably adapted to the curvature of the end face 24 of the shrink cap 10.

[0104] 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.

[0105] Finally, the turntable 44 rotates another 90° in the direction of arrow 46 so that the finished 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-dependent switch.

[0106] It should be understood that these figures only schematically represent the shrink cap 10 and its manufacture and that various other geometric or manufacturing modifications can be made without departing from the scope of the invention as 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 is produced by the welded or embossed seam (22), wherein the shrink cap (10) in the region between the first end (18) and the end face (24) is substantially mirror-symmetrical about a first symmetry plane (30), in, The end (34) of the welded or embossed seam (22) adjacent to the end surface (24) is arranged offset parallel to the first plane of symmetry (30).

2. The shrink cap according to claim 1, 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 is offset parallel to the first plane of symmetry (30).

3. The shrink cap according to claim 2, wherein: The engagement surface (68) inside the shrink cap (10) defines a boundary line that is curved in an arc shape.

4. The shrink cap according to claim 1, 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 to be offset parallel to the first symmetry plane (30) by at least 1 / 10 of the height (h1) at an end (34) adjacent to the end face (24).

5. The shrink cap according to claim 4, 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).

6. The shrink cap according to claim 1, wherein: 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).

7. The shrink cap according to claim 6, wherein: The free end (26) of the welded or embossed seam (22) does not protrude laterally from the shrink cap (10) in a direction orthogonal to the first plane of symmetry (30).

8. The shrink cap according to claim 6, wherein: The welded or embossed seam (22) comprises a free end (26), wherein the shaped portion (32) of the welded or embossed seam (22) which abuts against the end face (24) directly or with the intervening bonding agent extends over the area between the free end (26) and the end (34) adjacent to the end face (24).

9. The shrink cap according to claim 6, in, 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, or The welded or embossed seam (22) is directly and completely against the end surface (24) or is completely against the end surface (24) through the intervening bonding agent.

10. The shrink cap according to claim 6, wherein: The shaped portion (32) of the welded or embossed seam (22) is pressed against the end face (24).

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

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

13. The shrink cap according to claim 6, wherein: The end face (24) is convexly curved, and wherein the shaped portion (32) of the welded or embossed seam (22) extends parallel to the convexly curved end face (24).

14. A temperature-dependent switch comprising a shrink cap according to any one of claims 1-13.

15. A method of manufacturing a shrink cap (10), the method comprising: a) providing a heat shrink tubing segment (40), the heat shrink tubing segment comprising a first opening (19) at a first end (18) and a second opening (21) at a second end (20), and the heat shrink tubing segment being substantially mirror-symmetrical with respect to a first plane of symmetry (30), b) pressing the heat shrink tubing sections (40) together at the second end (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), wherein the welded or embossed seam (22) is produced offset parallel to the first plane of symmetry (30), 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) is bent.

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