Shrink cap and method of manufacturing shrink cap

Abstract

To provide a shrink cap that effectively prevents problems of personal injury and the risk of damage to other devices.SOLUTION: The invention relates to a shrink cap (10) for receiving a temperature-dependent switch (12). The shrink cap (10) includes an open first end (18) for sliding onto the switch (12), and a closed second end (20) which is closed by a welded or embossed seam (22) that extends from a closed end face (24). The closed end face (24) is arranged in the area of the second end (20) and results from the welded or embossed seam (22). The welded or embossed seam (22) is formed such that a formed section (32) of the welded or embossed seam (22) bears against the end face (24) directly or with an interposed joining agent.SELECTED DRAWING: Figure 2B

Description

[Technical field]

[0001] The present invention relates to a shrink cap and a method for manufacturing the shrink cap.The present invention further relates to a temperature dependent switch comprising a shrink cap according to the invention. [Background technology]

[0002] A typical shrink cap and a typical method for producing such a shrink cap are disclosed in European Patent 0 857 562.

[0003] Such shrink caps are usually held in bulk, pressed onto the electrical device to be protected, such as a temperature-dependent switch, and then shrunk using hot air to create a covering that protects the device from dirt, moisture and electrical contact with other components. The connecting elements of the device, often configured as strands or cables, protrude from this covering.

[0004] Such shrink caps are usually manufactured by first cutting a section of heat shrink tubing to length from the heat shrink tubing and then forming a welded or embossed seam at one of its ends. For this purpose, the section of heat shrink tubing is pressed together at said ends and the welded or embossed seam is created, for example, by two welding stamps acting on the ends of the section of heat shrink tubing from opposite sides by pressure and heat.

[0005] Because the welded or embossed seam is formed by pressing one end of the heat shrink tubing together and joining the longitudinal halves of the heat shrink tubing that are pressed together, the welded or embossed seam is typically about twice the wall thickness of the remainder of the heat shrink tubing. This results in a relatively stiff and rigid welded or embossed seam.

[0006] The welded or embossed seam protrudes from the closed end created by the welded or embossed seam on the heat shrink tubing or shrink cap, respectively. Due to the manufacturing process, the protruding free end of a welded or embossed seam typically has a very sharp edge that remains when the shrink cap is shrunk onto the device it is protecting.

[0007] In both the assembly of the shrink-capped device and the subsequent processing of the shrink-capped device, many process steps are typically performed manually and the people performing these process steps are unable to wear protective gloves because they are required to perform very delicate motorized operations.

[0008] Due to the sharp edges of the welded or embossed seams, this type of manual work can subject people to repeated injuries, which of course is a major drawback.

[0009] Therefore, to avoid these injuries, people often grab the covered element with the connecting cable rather than grabbing the covered element with the shrink cap itself, which often weakens the connection between the connecting cable and the covered element or breaks completely during further manipulations that are required, and devices made from such elements often malfunction.

[0010] In particular, if the device is, for example, a temperature-dependent switch for protecting a coil from overheating, the switch housed in the shrink cap will be in direct contact with, for example, the coil of an electric motor. The switch is electrically connected in series with the coil and interrupts the electric circuit if the temperature of the coil exceeds a predetermined value. For this purpose, in a known manner, a bimetallic switching mechanism is arranged inside the temperature-dependent switch.

[0011] To ensure this protective function, the switch must be located inside the coil, or at least very close to it. Sharp edges on the shrink cap could cause damage to the coil, which is of course a disadvantage.

[0012] According to EP 0 857 562 the above mentioned problems are solved by re-processing the shrink cap after the welded or embossed seam has been formed, during which the welded or embossed seam is folded over with a forming punch. This bending causes the sharp free edges of the welded or embossed seam to be rolled up or folded over, in other words, so that they no longer protrude straight out from the front face of the shrink cap.

[0013] This measure effectively prevents the aforementioned personal injury problems and the risk of damage to other equipment.

[0014] Nevertheless, there is still potential for improvement in the manufacture of such shrink caps. For example, as described in European Patent 0 857 562, it has been shown that shrink caps with welded or embossed seams bent more than 90° become mechanically unstable and therefore break more easily. This can lead to open areas in the shrink cap, which can result in a fundamental loss of the protective function of the shrink cap. Furthermore, this can impair the voltage or high voltage resistance of the shrink cap, which is an important property that must be guaranteed by the shrink cap, especially when used for temperature-dependent switches. Summary of the Invention [Problem to be solved by the invention]

[0015] It is therefore an object of the present invention to provide a shrink cap and a method for manufacturing such a shrink cap which makes it possible to eliminate or at least reduce the above-mentioned problems, thereby in particular reducing the risk of damage or injury which may be caused by such a shrink cap and at the same time ensuring a mechanically stable, tightly sealed and voltage-resistant shrink cap. [Means for solving the problem]

[0016] According to the invention, this object is solved by a shrink cap for sliding over a temperature-dependent switch, the shrink cap having an open first end for sliding over the switch and a closed second end closed by a welded or embossed seam extending from the closed end face, the closed end face being arranged in the region of the second end and arising from the welded or embossed seam, the welded or embossed seam being formed such that a formed portion of the welded or embossed seam abuts the end face directly or indirectly by means of an interposed bonding agent.

[0017] According to a further aspect of the present invention, the above object is achieved by a method for manufacturing a shrink cap comprising the steps of: a) providing a section of heat shrink tubing having a first opening at a first end and a second opening at a second end; b) pressing the heat shrink tubing sections together at their second ends to create a welded or embossed seam to close the second opening and create a closed end in the region of the second ends; c) forming a portion of the welded or embossed seam such that the formed portion of the welded or embossed seam abuts the end face directly or with an intervening bonding agent.

[0018] In contrast to what is proposed in EP 0 857 562, according to the present invention the welded or embossed seam is not only bent, folded or rolled over 90° or more towards the end face of the shrink cap, but is also formed so as to at least partially contact the end face. Preferably, the welded or embossed seam is folded over approximately 90° and disposed towards the end face of the shrink cap, so that at least a portion of the welded or embossed seam abuts the end face of the shrink cap either directly or indirectly by means of an intervening bonding agent.

[0019] This has several advantages: first, the shrink cap and thus the device in which it is used (e.g., a temperature-dependent switch) are made shorter. This small size is advantageous both in terms of bulk storage of the shrink cap and in terms of handling and mounting options for the shrink cap. Furthermore, it has been shown that by attaching the welded or embossed seam to the end face of the shrink cap, the risk of injury or damage is further reduced, since the sharp edges of the welded or embossed seam are completely attached to the end face of the shrink cap and do not protrude from the shrink cap at all, and therefore are barely accessible. Furthermore, it has been shown that at the end of the shrink cap, the welded or embossed seam abutting the end face of the shrink cap additionally increases the wall thickness at the end of the shrink cap, creating a kind of double or multiple wall. This not only creates additional mechanical stability. Initial tests by the applicant have also shown that this can significantly improve the high voltage resistance of the shrink cap. While conventional shrink caps exhibit a high voltage resistance of the order of 1.5-2.5 kV, the shrink cap of the present invention can achieve a high voltage resistance of 3.5 kV or more.

[0020] In this way, the above objective is completely achieved.

[0021] In a refinement, the welded or embossed seam has a free end and an end adjacent the end face, and the formed portion of the welded or embossed seam abuts the end face directly or with an intervening bonding agent and extends over the area between the free end and the end adjacent the end face.

[0022] Thus, the welded or embossed seam preferably contacts the end face of the shrink cap at least in a central portion extending between the free end and the end adjacent the end face.

[0023] In a further refinement, it is preferred that more than 50% of the area of ​​one side of the welded or embossed seam that abuts the end face abuts the end face either directly or with the aid of an intervening bonding agent.

[0024] In other words, it is preferred that the majority of the welded or embossed seam abuts the end face of the shrink cap, which further improves the mechanical stability and high voltage resistance of the shrink cap.

[0025] It is particularly preferred that the welded or embossed seam completely abuts the end face, either directly or indirectly by means of an intervening bonding agent.

[0026] The welded or embossed seam is preferably bent 90° and placed on one side relative to the end face of the shrink cap. Preferably, the welded or embossed seam does not protrude beyond the outer edge or circumference of the shrink cap. In this way, the greatest 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 reduced to a minimum.

[0027] In a further refinement, a formed portion of the welded or embossed seam is pressed against the end face.

[0028] This preferably results in a seamless, essentially wrinkle-free welded or embossed seam that is affixed to the end face of the shrink cap. Preferably, part or all of the welded or embossed seam is thermoformed or hot-formed by heating with external hot air and / or a thermoforming die and then pressed onto the end face of the shrink cap, resulting in a very compact shrink cap, which has a high level of stability and high voltage resistance, especially in the area of ​​the end face.

[0029] In a further refinement, the formed part of the welded or embossed seam is fixed to the end face by means of a material lock.

[0030] For example, after a welded or embossed seam is manufactured and formed, a formed portion of the welded or embossed seam is glued or welded to the end face of the shrink cap, thereby additionally securing the formed portion of the welded or embossed seam to the end face so that it remains permanently attached to the end face.

[0031] In a further refinement, the end face of the shrink cap is convexly curved. Particularly preferably, the end face is curved when viewed in a longitudinal section of the shrink cap.

[0032] This further minimizes the risk of injury and damage caused by shrink caps. Additionally, the shape is particularly suitable for receiving temperature dependent switches, which are typically cylindrical or round.

[0033] In a further refinement, a formed portion of the welded or embossed seam extends substantially parallel to the convexly curved end face.

[0034] Thus, the formed portion of the welded or embossed seam rests against the front surface of the shrink cap like a second wall, further improving the compactness, mechanical stability, high voltage resistance and rigidity of the shrink cap.

[0035] In a further refinement, the shrink cap in the region between the first end and the second end is substantially mirror symmetrical with respect to the first plane of symmetry, and the welded or embossed seam at the end adjacent to the end face is positioned offset with respect to the first plane of symmetry.

[0036] In other words, the welded or embossed seam is not produced in the center of the plane of symmetry of the heat shrink tubing section on which the shrink cap is formed, but is off-center with respect to this first plane of symmetry, which has the advantage that the welded or embossed seam can be relatively large and does not protrude laterally beyond the edge of the shrink cap after it has been bent and affixed to the end surface. The welded or embossed seam, even if it is placed with one side completely against the end face of the shrink cap, does not protrude laterally beyond the end face, i.e. transverse to the first plane of symmetry. Thus, the free, usually sharp-edged, end of the welded or embossed seam does not protrude laterally beyond the end face of the shrink cap. Subsequent cutting or shortening of the welded or embossed seam is therefore omitted.

[0037] All of this is possible by locating the welded or embossed seam off-center or offset, even though the welded or embossed seam has a relatively large surface area. The large area configuration of the welded or embossed seam enhances the adhesion of the seam and facilitates handling when manufacturing the welded or embossed seam.

[0038] The interface plane of the welded or embossed seam at the end of the welded or embossed seam adjacent the end face is preferably offset parallel to the first plane of symmetry.

[0039] "Joint surface" here refers to the surface where the two longitudinal halves of the heat shrink tubing that are pressed together and joined when the welded or embossed seam is made are connected to one another. This joint surface extends parallel to the first plane of symmetry after the welded or embossed seam is produced. However, because a portion of the welded or embossed seam is formed in accordance with the present invention and is disposed relative to an end face of the shrink cap, the foregoing definition of "only" the parallel offset arrangement of the faying surfaces refers to the end of the welded or embossed seam that is adjacent to or disposed on the end face.

[0040] In a further refinement, the end face has a height measured perpendicular to the first plane of symmetry and the welded or embossed seam is offset parallel to the first plane of symmetry by at least 1 / 10 of the height, preferably at least 1 / 5 of the height, at the end adjacent the end face.

[0041] This allows the welded or embossed seam, when attached to the end face, to have a height, measured perpendicular to the first plane of symmetry, that is greater than half the height of the end face, thereby not protruding laterally beyond the end face.

[0042] As mentioned above, the improvements mentioned above and those defined in the claims do not only relate to the shrink-cap itself, but also to the temperature-dependent switch comprising such a shrink-cap. Likewise, these improvements relate to the method for manufacturing the shrink-cap according to the invention. This in particular leads to the following further improvements in the manufacturing method according to the invention:

[0043] In a further refinement, in step c), a portion of the welded or embossed seam is formed such that more than 50% of the area of ​​one side of the welded or embossed seam abutting the end face abuts the end face directly or with an intervening bonding agent.

[0044] In a further refinement, in step c), a portion of the welded or embossed seam is formed such that it completely abuts the end face, either directly or indirectly by means of an intervening bonding agent.

[0045] In a further refinement, in step c) or after step c), a portion of the welded or embossed seam is pressed against the end face. Before or during this pressing step, the welded or embossed seam is preferably heated so that it can be more easily formed.

[0046] In a further refinement, a part of the welded or embossed seam is fixed to the end face in a material locking manner in step c) or after step c).

[0047] In a further refinement, a portion of the welded or embossed seam is formed in step c) such that the formed portion extends substantially parallel to the end face.

[0048] In a further refinement, the welded or embossed seam produces an offset parallel to the first plane of symmetry of the shrink tube portion in step b).

[0049] In a further refinement, in step b) the welded or embossed seam is generated offset from a first plane of symmetry of the shrink tube portion, and the welded or embossed seam generated in step b) is essentially mirror symmetric with respect to a second plane of symmetry offset parallel to the first plane of symmetry.

[0050] In a further refinement, the welded or embossed seam produced in step b) is generated offset from a first plane of symmetry of the shrink tube portion, and the welded or embossed seam produced in step b) is substantially mirror symmetrical with respect to a second plane of symmetry, the second plane of symmetry being offset from the first plane of symmetry by at least 1 / 10 of the height, preferably by at least 1 / 5 of the height, measured orthogonally to the first plane of symmetry.

[0051] In a further refinement, the welded or embossed seam is formed in step c) in such a way that the free end of the welded or embossed seam does not protrude beyond the end face in a direction perpendicular to the first plane of symmetry.

[0052] It is understood that the features mentioned above and those to be described below can be used not only in the combinations indicated in each case, but also in other combinations or by themselves, without departing from the scope of the invention. [Brief description of the drawings]

[0053] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. [Figure 1] 1 is a schematic diagram of a prior art shrink cap in several views; [Figure 2A] FIG. 2 is a side view of a shrink cap according to a first embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view of the shrink cap shown in FIG. 2A. [Figure 3A] FIG. 11 is a side view of a shrink cap according to a second embodiment of the present invention. [Figure 3B] FIG. 3B is a cross-sectional view of the shrink cap shown in FIG. 3A. [Figure 4] 11A-11C are side and plan views from the front of a shrink cap according to a third embodiment, where the shrink cap is shown in an intermediate state occurring during manufacture; [Figure 5A] FIG. 13 is a side view of a shrink cap according to a third embodiment, the shrink cap here shown in a completed final state. [Figure 5B] FIG. 5B is a cross-sectional view of the shrink cap shown in FIG. 5A. [Figure 6] 5A-5C are several schematic manufacturing steps for producing a shrink cap according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] 1 shows various schematic views of a prior art shrink cap, generally designated 10.

[0055] 1 can also be considered as an intermediate state during the manufacture of a shrink cap 10 according to the invention. In other words, a shrink cap 10 according to the invention, which will be described in more detail below, is initially manufactured in a conventional manner, but is further manufactured in a manner that differs from shrink caps known from the prior art.

[0056] The shrink cap 10 is used in particular to receive a temperature-dependent switch 12, the outer connection 14 of which is shown here in simplified form as a twisted wire. Such temperature-dependent switches 12 are used to monitor electrical devices. In particular, they are used for this purpose to de-energize the electrical device to be monitored in the event of overheating. Here, the switch 12 is usually installed inside the switch housing and comprises a temperature-dependent switching mechanism consisting of a bimetallic part. This bimetallic part changes its shape when a response temperature is exceeded, whereby the switching mechanism is moved from its closed position to its open position. The electrical circuit in which the switch 12 is installed is then opened. If the device to be monitored is then cooled again below the so-called reset temperature of the bimetallic part, this in turn snaps back into its initial position, whereby the switch is returned to its closed position. In this way, the temperature-dependent switching behavior of the switch 12 is realized.

[0057] The shrink cap 10 according to the present invention functions, inter alia, to provide external protection and electrical shielding for the switch 12. The shrink cap 10 is placed over the switch 12, attached to the switch 12, or shrunk onto the switch 12 so that in the final state, the shrink cap 10 surrounds the switch 12 on all sides.

[0058] However, it is understood that the shrink cap 10 according to the invention is in principle also suitable for receiving other devices and is not limited to receiving a temperature dependent switch as shown in the present case.

[0059] Shrink cap 10, the cross section of which is shown at 16, has a first end 18 slid onto switch 12 and then shrunk onto switch 12 using hot air so that only outer connection portion 14 protrudes from the sheath thus formed. First end 18 is thus configured as an open end including a first opening 19.

[0060] A second end 20 of the shrink cap 10 opposite the first end 18 is closed. Here, the shrink cap 10 comprises a welded or embossed seam 22 provided in the region of the second end 20. By means of 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 comprises, in the region of its second end 20, a closed end surface 24, which adjoins the welded or embossed seam 22.

[0061] Due to the manufacturing process, the welded or embossed seam 22 is configured as a fold or edge that projects straight out from the end surface 24 of the shrink cap 10. This fold or edge is relatively rigid or inflexible and has a relatively sharp edge 28 at its front free end 26.

[0062] The free front edge 28 of the face side of the welded or embossed seam 22 is curved in the shape of a circular arc when viewed from above (see the upper center part of FIG. 1 ). This is also due to the manufacturing process, in which the shrink cap 10 is produced in the region of its second end 20 by pressing them together and then welding or embossing the initially still open end (opening 21) to produce the welded or embossed seam 22, as will be explained in more detail below.

[0063] At 16, the shrink cap 10 is illustrated as being oval or elliptical in cross section. However, the shrink cap 10 may be approximately circular when viewed in cross section. The starting material used for the shrink cap 10 in the form of heat shrink tubing is typically circular or round in cross section, i.e., generally cylindrical.

[0064] The end surface 24 of the shrink cap 10 resulting from the welded or embossed seam 22 is configured to be convex, as can be seen particularly from the plan view from above at the top center of FIG. 1 and the side view at the bottom of FIG. 1. It is understood that the shape of the end surface 24 shown here is shown diagrammatically. In reality, this end surface 24 is usually convexly curved, but is usually not exactly round and regular as shown in this figure. However, as mentioned above, the manufacturing process results in an arc-like rounding or curvature of the end surface 24. Depending on the shape of the switch 12 onto which the shrink cap 10 is to be shrunk, the end surface 24 may be angled or substantially flat, and the welded or embossed seam 22 may extend along a straight line. However, to accommodate a substantially circular switch 12, a circular or curved welded or embossed seam 22 is advantageous.

[0065] FIG. 1 shows the state of the shrink cap 10 after the welded or embossed seam 22 has been produced. This state corresponds to the final state of the majority of shrink caps used in the prior art to accommodate temperature-dependent switches. In this state, the shrink cap 10 is essentially mirror symmetrical with respect to a first plane of symmetry, indicated by the reference numeral 30 in FIG. 1. The term "essentially mirror symmetrical" is used in this case to indicate that in practice there is no absolutely exact mirror symmetry. In principle, however, this mirror symmetry exists and slight deviations, usually in the range of millimeters or tenths, which occur in practice due to the manufacturing process, can be neglected.

[0066] The shrink cap 10 used in the prior art, if used in the condition shown in FIG. 1 and not further processed, poses a relatively high risk of injury to persons and a risk of damage to the part of the machine in which the temperature dependent switch 12 is housed along with the shrink cap 10, due to the relatively sharp edges 28 at the end faces 26 of the welded or embossed seams 22.

[0067] Thus, in accordance with the present invention, shrink cap 10 is further processed starting from the intermediate state shown in Fig. 1, where welded or embossed seam 22 is formed such that at least a formed portion 32 of welded or embossed seam 22 is in contact with end surface 24 of shrink cap 10. In other words, welded or embossed seam 22 is bent at about 90° or slightly more and placed at least partially against end surface 24. The formed portion 32 of welded or embossed seam 22 placed against end surface 24 of shrink cap 10 is adjacent to end surface 24, either directly or via an intervening bonding agent.

[0068] In Figures 2A, 2B, 3A and 3B two different embodiments of the shrink cap 10 according to the invention are shown in their final state. Figures 2A and 3A show a side view of the shrink cap 10. Figures 2B and 3B show a longitudinal section of the shrink cap 10. The sections are perpendicular to a first plane of symmetry 30 shown in dashed line in Figure 1.

[0069] As can be seen from FIGS. 2 and 3, the shrink cap 10 according to the invention, in its final state, is not generally mirror symmetrical with respect to the first plane of symmetry 30. As shown in FIG. However, the left portion of the shrink cap 10 is still mirror symmetrical with respect to the first plane of symmetry 30. In other words, apart from the welded or embossed seam 22, the completed shrink cap 10 is essentially mirror symmetrical with respect to the first plane of symmetry 30.

[0070] In the first embodiment shown in Figures 2A and 2B, the welded or embossed seam 22 is partially folded over and 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, the folding back of the welded or embossed seam 22 may result in a small bead that protrudes slightly forward from the end face 24. Overall, however, the effective length of the shrink cap 10 is significantly shortened by the folded arrangement of the welded or embossed seam 22 against the end face 24. Furthermore, the sharp edges 28 of the welded or embossed seam 22 no longer protrude from the front of the shrink cap 10. The risk of injury and damage is therefore significantly reduced. Furthermore, in the area of ​​the folded welded or embossed seam 22, the high voltage resistance of the shrink cap 10 is improved, since the welded or embossed seam 22 forms, as it were, an additional layer in this portion 32, thereby increasing the wall thickness and therefore also the high voltage resistance of the shrink cap.

[0071] In the second embodiment shown in Figures 3A and 3B, the welded or embossed seam 22 is applied almost completely or at least partially to a greater extent to the end face 24 of the shrink cap than in the second embodiment (see Figures 2A and 2B). The welded or embossed seam 22 is preferably pressed against the end face 24, which preferably results in a seamless and essentially wrinkle-free welded or embossed seam 22 being applied to the end face 24 of the shrink cap 10. The formation of the aforementioned type of welded or embossed seam 22 is preferably carried out under the influence of heat, as will be explained in more detail below.

[0072] Depending on the intended application, the portion 32 of the welded or embossed seam 22 that is affixed to the end surface 24 is preferably either loosely affixed to the end surface or connected to the end surface by an additional welding or bonding process.

[0073] It is particularly preferred that the shaped portion 32 of the welded or embossed seam 22 according to the second embodiment shown in Figures 3A and 3B has at least a majority (i.e., greater than 50% area) of the bottom surface 36 folded over the end surface 24 positioned in contact with the end surface 24.

[0074] Depending on its size, the welded or embossed seam 22 may protrude considerably from the end face 24 in the initial state shown in FIG. 1 and may protrude downwards or laterally from the shrink cap 10 when the welded or embossed seam 22 is folded and placed, as can be seen in particular in FIG. 3B. To completely avoid any risk of injury or damage, it is advantageous to cut the welded or embossed seam 22 to length or in the region of the end face edge 26. However, this method has the disadvantage that leakages occur, which impair the perfect sealing of the shrink cap 10 in the region of the second end 20. For example, cracks or holes may appear in the welded or embossed seam 22, through which impurities can penetrate into the interior of the shrink cap 10. Needless to say, this is a fundamental drawback.

[0075] According to a third embodiment of the shrink cap 10 shown in Figures 4, 5A and 5B, the welded or embossed seam 22 is arranged offset parallel to the above-mentioned first plane of symmetry 30. In other words, the welded or embossed seam 22 is not generated in the center of the shrink cap 10, but is offset in height relative to the plane of symmetry 30. Figure 4 shows an intermediate state of the shrink cap 10 after the welded or embossed seam 22 has been generated (before the welded or embossed seam 22 is formed). In this state, the shrink cap 10 according to the third embodiment is therefore essentially mirror symmetrical with respect to the first plane of symmetry 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 as a whole is not essentially mirror symmetrical with respect to the first plane of symmetry 30.

[0076] The right part of FIG. 4 shows the shrink cap 10 in a top view from the front through the first opening 19. Here, the welded or embossed seam 22 can be seen as a linear offset parallel to the first plane of symmetry 30. This line is formed by a joining surface 68 along which the two longitudinal halves of the heat shrink tube that are pressed together and joined are joined when the welded or embossed seam 22 is produced. This joining surface 68 extends parallel to the first plane of symmetry 30 when producing the welded or embossed seam 22 according to the third embodiment shown diagrammatically in FIG. 4. In other words, the joining surface 68 lies in a second plane of symmetry 70 to which the welded or embossed seam 22 is essentially mirror symmetric and parallel to the first plane of symmetry 30.

[0077] Now, starting from the intermediate state shown in Fig. 4, when the welded or embossed seam 22 is formed and only partially affixed to the end surface 24 according to the first embodiment or entirely affixed thereto according to the second embodiment, the sharp edges 28 of the welded or embossed seam 22 no longer protrude sideways or downwards from the shrink cap 10 (see Figs. 5A and 5B). No additional work, such as shortening the welded or embossed seam, is required. The risk of injury or damage is minimized.

[0078] 5A and 5B, the welded or embossed seam 22 has in fact been folded over in its entirety or almost its entirety. However, it will be understood that the end or beginning 34 of the welded or embossed seam 22 adjacent the end face 24 is still offset parallel to the described first plane of symmetry 30. This end or beginning 34 therefore means in particular the inner boundary of the welded or embossed seam 22, where the welded or embossed seam 22 begins or where the welded or embossed seam meets the end face 24 of the shrink cap 10.

[0079] According to a third embodiment shown in figures 4, 5A and 5B, the end 34 of the welded or embossed seam 22 adjacent to the end face 24 is offset from the first plane of symmetry 30 by preferably at least 1 / 10 of the height h1, more preferably at least 1 / 5 of the height h1 and especially preferably at least 1 / 3 of the height h1. Said height h1 means the dimension of the shrink cap 10 measured perpendicular to the first plane of symmetry 30 in the region of the first end 18. Said offset is indicated by the symbol x in the right part of figure 4.

[0080] FIG. 6 illustrates generally how the shrink cap 10 according to the present invention may be manufactured from heat shrink tubing 38.

[0081] First, short heat shrink tubing sections 40 having opposing open ends 18, 20, each end containing an opening 19, 21, are cut from the heat shrink tubing 38. These heat shrink tubing sections 40 are then slid, one after the other, onto a profile 42 placed on a turntable 44.

[0082] After the heat shrink tubing portions 40 are pressed onto the profile 42, the turntable 44 is rotated 90° in the direction of the arrow 46 shown in FIG. 6 (here, clockwise) so that each heat shrink tubing portion 40 reaches the welding position 48.

[0083] At the welding position 48, the heat shrink tubing section 40 is heated and preformed by hot air, indicated at 50, and two welding punches 52 simultaneously act on the second end 20 of the heat shrink tubing section 40, thereby closing the second opening 21 in the heat shrink tubing section 40 and creating the welded or embossed seam 22.

[0084] One of these two welding stamps 52 is shown diagrammatically in Figure 6. Also shown at 54 is the position where the welding stamp 52 engages the heat shrink tubing section 40. Generally, the welding stamp 52 comes from above and below, thereby pressing the heat shrink tubing ends together, and the welded or embossed seam 22, as shown in Figure 1 or Figure 4, is created by heating.

[0085] Here, shrink cap 10 has the intermediate state shown in FIG. 1 or FIG.

[0086] Now, the turntable 44 is rotated another 90° in the direction of the arrow 46 so that the shrink cap 10 reaches the forming position 56. Here, the welded or embossed seam 22 is preferably heated again by hot air 58 to facilitate its formation. At the same time, a forming or pressing punch 60 is pressed against the welded or embossed seam 22 from the front to bend the seam 22 and press it against the end surface 24 of the shrink cap 10.

[0087] A forming or pressing punch 60 is shown diagrammatically on the right hand side of FIG. 6 in both a top view and a side view, the side view including a heater 62 that can be used in place of hot air 58 to precisely heat the welded or embossed seam 22 before or during forming.

[0088] The forming or press punch 60 includes a forming area 64 having arcuate flanks that preferably conform to the curvature of the end face 24 of the shrink cap 10 .

[0089] As already mentioned, the welded or embossed seam 22 may be additionally connected, i.e., additionally welded or glued, to the end surface 24 during this manufacturing process, or the seam 22 may be "only" pressed against or against the end surface 24.

[0090] Finally, the turntable 44 again rotates 90° in the direction of the arrow 46, so that the finished shrink cap 10 reaches an ejection position 66 where it is ejected, for example by compressed air. The shrink caps 10 thus produced can be stored as bulk material until they are used, for example to house a temperature dependent switch.

[0091] It will be appreciated that the present drawings merely illustrate the shrink cap 10 and its manufacture in a schematic manner, and that various further geometric or manufacturing modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. an open first end (18) configured to receive a temperature dependent switch; a second end (20) closed by a welded or embossed seam (22) extending from a closed end surface (24); The closed end (24) results from a welded or embossed seam (22); A shrink cap (10) in which a welded or embossed seam (22) is formed such that a formed portion (32) of the welded or embossed seam (22) abuts the end face (24) directly or with a bonding agent interposed between the welded or embossed seam (22) and the end face (24).

2. 2. The shrink cap of claim 1, wherein the welded or embossed seam (22) has a free end (26) and an end (34) adjacent the end face (24), and the formed portion (32) of the welded or embossed seam (22) that abuts the end face (24) directly or with an interposed bonding agent extends over an area between the free end (26) and the end (34).

3. 2. The shrink cap of claim 1, wherein greater than 50 percent of the area of ​​one side (36) of the welded or embossed seam (22) that abuts the end surface (24) abuts the end surface (24) either directly or with an intervening bonding agent.

4. 2. The shrink cap of claim 1, wherein the welded or embossed seam (22) fully abuts against the end surface (24), either directly or with the intervening adhesive.

5. The shrink cap of claim 1, wherein the formed portion (32) of the welded or embossed seam (22) is pressed against the end surface (24).

6. 2. The shrink cap of claim 1, wherein the formed portion (32) of the welded or embossed seam (22) is secured to the end surface (24) in a material-locking manner.

7. 2. The shrink cap of claim 1, wherein said end surface (24) is convexly curved.

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

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

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

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

12. 12. The shrink cap of claim 11, wherein a height (h2) of the welded or embossed seam (22), measured perpendicular to the first plane of symmetry (30), as measured from an end (34) of the welded or embossed seam (22) adjacent an end face (24) to a free end (26) of the welded or embossed seam (22) is greater than half the height (h1) of the end face (24).

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

14. A method of manufacturing a shrink cap (10), comprising the steps of: a) providing a heat shrink tubing section (40) having 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) to create a welded or embossed seam (22) to close the second opening (21) and form a closed end surface (24) in the region of the second ends (20); c) forming a portion (32) of the welded or embossed seam (22) such that the formed portion (32) of the welded or embossed seam (22) abuts the end surface (24) either directly or with an intervening bonding agent.

Images