Method for producing a cable feedthrough

Abstract

The invention relates to a production method for producing a cable feedthrough and in particular for the partially automatable assembling of a moisture-tight cable feedthrough, which has a high electromagnetic shield. The method includes the following steps: a. providing a housing (2) having a bore (2a) for the cable feedthrough; b. plugging a sleeve (3) over the end portion of a connection cable (1) having a shield (5); c. exposing and stripping the connection wires (4) of the connection cable (1); d. braiding and bending over the wires of the braided shield (5) by 180 degrees; e. pushing an elastic assembly aid (7) over the bent wires of the shield (5); and, f. pressing the sleeve (3) into the housing bore (2a) into an end position.

Description

[0001] 00463214-0009 12 / 27 / 2025 PCT / DE0Ö2^|ößffi131 27- 12-2025- uQ463214-ÜÖ08

[0002] Method for producing a cable gland

[0003] The invention relates to a method for manufacturing a cable gland, and in particular to the final assembly steps before the cable gland is completed; therefore, it is referred to below as an assembly method. A cable gland is often a mass-produced item and, for cost reasons, requires at least partial automation of its manufacture. A cable gland often needs to be moisture-proof and provide high electromagnetic shielding. The assembly steps must ensure that the cable gland can be manufactured to a consistently high quality, even if some assembly steps are performed manually.

[0004] A typical application for such a cable gland is described below:

[0005] For example, a measuring device consists of a sensor, a housing, and an electrical connection cable containing power supply lines and measuring leads. The sensor receives electrical energy via the power supply lines. Depending on the physical operating principle, the sensor generates an electrical measurement signal, which is transmitted via the measuring leads to an electrical evaluation unit. It is characteristic of such systems that the connection cable must be well shielded against external electromagnetic radiation, as this would otherwise induce voltages in the measuring leads that distort the measurement signals. Furthermore, it is often necessary for the cable entry point to be hermetically sealed.

[0006] The connecting cables have a multi-layered construction, consisting of an outer plastic sheath and a metal braid as the next layer. This metal braid serves as shielding against electromagnetic interference. 00463214-0010 27.12.2025 PCT / DE0S£^|ÖS 131

[0007] 2

[0008] It often consists of interwoven bare wires, all of which are therefore in electrical contact with each other. The power supply and measuring leads are arranged within the metal braid. The braid is so densely woven that it provides the necessary shielding against external electromagnetic interference.

[0009] In practice, the following problem arises:

[0010] The denser the metal braid, the better the shielding. On the other hand, a dense metal braid also stiffens the cable. There are applications that require the most flexible cable possible, for example, with moving assemblies such as assembly robots.

[0011] The metal braid should therefore have as little impact as possible on the cable's flexibility. The aim is to make the metal braid dense enough to achieve the necessary parameters for protection against electromagnetic interference, while simultaneously ensuring the cable remains as flexible as possible.

[0012] The shielding can lose its effectiveness if the structure of the metal braid is altered. Such alterations are unavoidable at the connection point between the measuring cable and a sensor. At this point, the connecting wires are exposed, stripped, and soldered to the electrical terminals of the sensor or another measuring device. The metal braid must be removed beforehand. After connecting the leads to the sensor, the metal braid must, in most cases, be electrically connected to the sensor's metal housing. Care must be taken to ensure that the spacing between the thin wires of the metal braid remains small enough to guarantee shielding against electromagnetic radiation along this section of the cable. Furthermore, a hermetic seal must also be ensured.

[0013] The sensors or other devices with comparable requirements described above are often manufactured in large quantities. The described processes for contacting the cables with the sensor or other device are 00463214-0011 27.12.2025 PCT / DE0S£^ / |ößffi131

[0014] 27-12-2025-00463214-0011

[0015] 3

[0016] This is still mostly done by hand. Handling the metal braid, in particular, requires a certain degree of fine motor skills and care from the installer. If the installer does not carefully unravel and position the metal braid, the necessary shielding against electromagnetic interference may no longer be guaranteed. Furthermore, the wires of the metal braid can sometimes be sheared off at the edge of the housing bore when the sleeve-shaped cable gland is pressed into the housing. These installation errors are especially critical if the cable protection sleeve is not made of metal.

[0017] If electromagnetic quality control reveals that the shielding is insufficient, the sensor must be disassembled and reassembled. This results in considerable additional work and therefore significant additional costs.

[0018] Therefore, there is a need for an assembly method that allows for reliable handling of the metal mesh and thus ensures safe shielding against electromagnetic radiation. Furthermore, a good hermetic seal should be achieved.

[0019] Various designs for cable penetrations are known from the state of the art:

[0020] A cable entry device is known, for example, from DE 19825672 A1. This document describes a cable entry device with a plug made of an elastic material, wherein the plug comprises a through-hole for receiving a cable and a groove for inserting the plug into a hole in a wall. The cable entry device further comprises a strain relief unit, with an EMC-compliant cover for the strain relief unit being provided. A shield designed as a frustoconical wire mesh surrounds a web-shaped leg of the strain relief unit and a conical section of the plug. 00463214-0012 27.12.2025 PCT / DE0S£^ / |ööffi131

[0021] ■27-

[0022] 4

[0023] A cable entry device of the aforementioned type is also known from EP 0780 924 A2. This describes a two-part cable entry device, wherein an internal locking element, which can be considered a plug made of an elastic material, consists of an elaborate meander-shaped structure that can be compressed and locked by a sliding ring.

[0024] A high-frequency (HF)-tight cable entry device is further disclosed in DE 4038690 A1. This document describes the combination of a carrier plate with a pressure plate that is detachably attached by hooking or snapping into place, wherein the cable can be clamped between the two aforementioned plates by a trough-shaped recess. This cable entry device is HF-tight, but it is not suitable for solving the problem described at the outset.

[0025] No prior art document addresses the problem described at the beginning, namely how to position a shielding braid at the cable end in such a way as to ensure reliable shielding against external electromagnetic radiation, i.e., that the shielding braid is arranged in a largely uniform structure around the cable circumference at the cable end and that the cable entry is also moisture-proof and fits tightly and centrally.

[0026] The object of the invention is therefore to create an assembly method for producing a moisture-proof cable gland that also has good shielding against electromagnetic radiation.

[0027] The problem is solved by an assembly method according to claim 1. Claims 2 to 4 describe specific embodiments of the invention.

[0028] The assembly process comprises the following steps:

[0029] The starting point is the provision of an enclosure with a bore for a cable entry. The requirement must be met that external moisture and electromagnetic radiation cannot penetrate the enclosure. 00463214-0013 27.12.2025 PCT / DE0S£^ / |ößffi131

[0030] 27-12-2025--0046S214-.0Ö13

[0031] 5

[0032] The cable can penetrate the housing through a bore or via the cable gland. For this purpose, the end of the connecting cable is pre-assembled using the following steps:

[0033] A sleeve is placed over the end section of the connecting cable. The housing is also provided with the hole into which the sleeve and cable end are to be inserted and secured.

[0034] The end section of the connecting cable is prepared as follows: The connecting wires are exposed as required and stripped at their ends, i.e., left bare metal and suitable for soldering or screwing onto a device or component, e.g., a sensor. The connecting wires are enclosed in a plastic tube. This plastic tube is surrounded by a wire braid, which serves to electromagnetically shield the connecting wires, particularly the measuring leads. It should be emphasized that the plastic tube is not strictly necessary to implement the invention. Rather, the wire braid can also be arranged directly over the connecting wires.

[0035] - In the next step, the wire mesh is unraveled with a suitable tool, e.g. a thin screwdriver, and bent back 180 degrees.

[0036] In the next step, a ring-shaped mounting aid made of a firm and stable rubber or plastic with elastic properties is manually slid a few millimeters over the bent wire mesh. The inner diameter of the mounting aid is dimensioned so that it tightly grips the bent wire mesh. The mounting aid can have a circular or rectangular cross-section. This completes the pre-assembly.

[0037] These work steps are still done manually.

[0038] In the next step, the sleeve is pressed into the housing bore using a pressing device:

[0039] - First, the mounting aid rests against the outer edge of the bore. It is for the 00463214-0014 27.12.2025 PCT / DE0S£^ / |ößffi131

[0040] 27= 12”2025”:004'63214”0014

[0041] 6

[0042] The expert clearly stated that the housing bore is smaller than the outer diameter of the mounting aid.

[0043] - When the sleeve is pressed in, the ring-shaped mounting aid, which rests against the housing wall, is moved backward along the bent wire braid of the shielding and the connecting cable on the sleeve. This ensures that the wires of the wire braid are held taut against the outer diameter of the sleeve and cannot spread out when they pass the edge of the bore. This prevents laterally protruding wires of the wire braid from being sheared or torn off at the edge of the bore.

[0044] The sleeve has a circumferential stop on its outer circumference. The sleeve is inserted into the bore until it reaches this stop. In this final position, the mounting aid acts as a sealing element. To facilitate the sliding of the mounting aid over the wire mesh, a drop of silicone oil can optionally be added.

[0045] This step achieves two effects simultaneously:

[0046] Effect 1:

[0047] The mounting aid ensures that the wire mesh is pressed down evenly and smoothly, thus preventing the otherwise very irregularly protruding individual wires of the wire mesh from being positioned in a way that would negatively affect its shielding performance when pressed into the bore. It also prevents the wires from shifting relative to each other in such a way that they could potentially be sheared off at the sharp edge of the housing bore.

[0048] Effect 2:

[0049] The mounting aid remains on the cable sleeve and acts as a seal in the final state of assembly.

[0050] Thus, the assembly aid has a dual function:

[0051] During assembly, it smooths and fixes the shielding wires, and in the final state, the assembly aid acts as a seal. 00463214-0015 27.12.2025 PCT / DE0S£^ / |ößffi131

[0052]

[0053] 27-12-20215-W463214-W1'

[0054] 7

[0055] The invention is explained in more detail with reference to schematic drawings:

[0056] Fig. 1 shows a housing with a bore and a cable with a shield and a sleeve attached to it.

[0057] Fig. 2 shows an undesirable assembly situation where the wires of a bent shielding braid could be sheared off during assembly.

[0058] Fig. 3 shows a mounting position where the shielding braid is bent over and the mounting aid has not yet been slid on.

[0059] Fig. 4 shows a mounting position in which the mounting aid has already been pushed a few millimeters over the shielding braid by hand.

[0060] Fig. 5 shows a mounting position in which the sleeve is already partially inserted into the housing bore and the mounting aid is shifted in the direction of the arrow.

[0061] Fig. 6 shows the final state of the assembly.

[0062] Fig. 7 shows a compilation of all phases of assembly.

[0063] Fig. 8 shows an enlarged perspective view of the assembled cable without housing.

[0064] Reference numeral list

[0065] 1 connection cable

[0066] 2 cases

[0067] 2a Housing bore

[0068] 3 Sleeve

[0069] 4 connecting wires

[0070] 5 wire mesh for electromagnetic shielding

[0071] 6. Plastic tubing over the wire mesh

[0072] 7. Mounting aid made of rubber or elastic plastic

[0073] Fig. 1 shows a housing (2) with a housing bore (2a) and a connecting cable (1) with a wire braid (5) for electromagnetic shielding, wherein a sleeve (3) is pushed onto the connecting cable (1). 00463214-0016 27.12.2025 PCT / DE0S£^ / |ößffi131

[0074] 8

[0075] Figure 2 illustrates a step in the process where the wire mesh (5) has been bent by hand by 180 degrees. The enlarged view shows that the elastic wires protrude in various directions after bending. This illustration also shows that individual wires can shear off when the sleeve (3) is inserted further into the housing bore (2a). The sheared-off wires are then missing, preventing a secure seal and a tight fit of the sleeve in the bore.

[0076] Fig. 3 shows a mounting position in which the wire mesh (5) for electromagnetic shielding is already bent over as in Fig. 2 and a mounting aid (7) with a circular cross-section is provided.

[0077] Fig. 4 shows a mounting position into which the mounting aid (7) was pushed by hand a few millimeters over the wire mesh (5).

[0078] Fig. 5 shows an assembly position in which the sleeve (3) has already been partially pressed into the housing bore (2a) by means of a pressing device. It is shown that the assembly aid (7) rests against the upper edge of the housing bore (2a). During this pressing process, the assembly aid (7) is moved until it reaches a shoulder on the sleeve (3). Depending on requirements, a groove may be provided into which the assembly aid (7) snaps. It is left to the expert to decide whether to additionally use a suitable lubricant to prevent excessive friction.

[0079] Fig. 6 shows the final position in which the sleeve (3) is completely received in the housing bore (2a) and thus the above-described object of the invention is fulfilled.

[0080] Figure 7 A - D schematically shows the assembly process in different phases.

[0081] Fig. 8 shows a perspective view of the assembled cable without the housing. The uniformly bent wire braid (5) is visible. It should be emphasized that this very uniform distribution of the 00463214-0017 27.12.2025 PCT / DE0S£^ / |ößffi131 was achieved with the aid of the assembly aid (7).

[0082] 27" 12-Ä02S~Qß4 214" 0017

[0083] 9

[0084] The wires of the wire mesh (5) were reached. This also ensures a concentric fit of the sleeve (3) and good electrical contact with the wall of the housing bore (2a) if the housing is made of metal.

Claims

00463214-0019 12 / 27 / 2025 PCT / D E0g)£^ / |ÖQffi 131 27-12-2025-004S32 14-001 9 10 Claims 1. A method for producing a cable gland, wherein the method comprises the following steps: a. Providing a housing (2) with a bore (2a) for cable entry, b. Fitting a sleeve (3) over the end section of a connecting cable (1) having a shield (5), c. Expose and strip the connecting wires (4) of the connecting cable (1), d. Unwind and bend the wires of the braided shield (5) by 180 degrees, e. Slide a tightly fitting elastic mounting aid (7) a few millimeters over the bent wires of the shielding (5), f. Pressing the sleeve (3) into the housing bore (2a) until it reaches a final position.

2. Method according to claim 1, wherein after step d a lubricant is applied to the wires of the shield (5).

3. Method according to claim 1, wherein the cross-section of the assembly aid (7) is rectangular.

4. Method according to claim 1, wherein the cross-section of the assembly aid (7) is circular.

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