Device and use of the device for stripping a cable

A device for stripping cable has a support roller arrangement and a work wheel arrangement. The support roller arrangement is on a rotation base rotatable about an axis of rotation and the work wheel arrangement is on a work wheel guide. The rotation base and the work wheel guide are connected via at least one guide and the work wheel guide is displaceable relative to the rotation base in a guide direction running transversely to the axis of rotation. The support roller arrangement has at least two support rollers each mounted on the rotation base so as to be rotatable about a support roller axis and the work wheel arrangement has a rolling wheel mounted on the work wheel guide so as to be rotatable about a rolling wheel axis. A clamping region is formed around the axis of rotation and between the support rollers and the rolling wheel.

TECHNICAL FIELD

The present teaching relates to a device for stripping a cable having an outer protective sheath, the device having a support roller arrangement and a work wheel arrangement, the support roller arrangement being arranged on a rotation base of the device that is rotatable about an axis of rotation and the work wheel arrangement being arranged on a work wheel guide, the rotation base and the work wheel guide being connected to one another via at least one guide and the work wheel guide being displaceable relative to the rotation base in a guide direction running transversely to the axis of rotation, the support roller arrangement comprising at least two support rollers each mounted on the rotation base so as to be rotatable about a support roller axis and the work wheel arrangement comprising a rolling wheel mounted on the work wheel guide so as to be rotatable about a rolling wheel axis and a clamping region being formed around the axis of rotation and between the at least two support rollers and the rolling wheel, which clamping region can, by displacing the work wheel guide in the guide direction relative to the rotation base, be enlarged and reduced depending on the displacement direction. The present teaching also relates to a use of this device for stripping a cable having an outer protective sheath that is to be removed by the stripping.

BACKGROUND

Shielded cables substantially consist of a shielded wire arrangement that has one or more conductors, at least one shielding layer surrounding the wire arrangement, and an outer protective sheath. The shielding layer and the protective sheath are arranged concentrically around the wire arrangement, the shielding layer shielding the wire arrangement against electrical or magnetic fields and the protective sheath arranged around the shielding layer offering in particular mechanical protection against external influences and electrical insulation of the wire arrangement.

The shielding layer of the shielded cable is often made of a shielding braid and a shield foil surrounding the shielding braid. The protective sheath in turn surrounds the shield foil. An additional problem with stripping is the static friction between the protective sheath and the shield foil. Sometimes, the protective sheath and shield foil are even glued or welded to one another. For stripping such cables, the protective sheath and the shield foil must be processed in one operation, since the protective sheath alone cannot be removed. In such situations, the stripping is particularly difficult because a part of the shielding layer must be removed, but the shielding braid of the shielding layer must not be damaged.

To connect shielded cables, it is necessary to sever the protective sheath around the cable at a specific distance from the cable end and then pull it off the shielding layer, optionally also with a shield foil. This process is also referred to as stripping. However, the shielding layer or at least the required part of the shielding layer must remain intact, since otherwise a functioning shield is not ensured or connection of the shield, usually to an electrical reference potential, is not possible at all after the cable is connected.

The shielding layer generally consists of an extremely thin and sensitive material, for example a thin aluminum foil, a plastics material film coated with metal (shield foil), a filigree wire mesh, or a plurality of such layers. The protective sheath, on the other hand, must be made of a resistant material, for example of resistant plastics materials, such as PUR, PVC, silicone, etc., and must have corresponding thicknesses. The protective sheath is significantly thicker than the shielding layer.

The stripping of shielded cables is therefore mostly done by hand and requires dexterity and experience. Known mechanical aids, such as wire strippers or rotary cutters, also require very careful and experienced handling, since they can also easily destroy the shielding.

The installation of numerous shielded cable connections, as required in the industrial production of electric cars for example, can therefore be a time-consuming undertaking.

EP 2 693 581 A1 discloses a device for stripping shielded cables having a blade arrangement that can be rotated around the cable and the infeed of which can be changed for making a cut in the protective sheath. An electronic detection device determines when the blades come into contact with the shield, but it is usually too late when the detection device strikes because the shield or the conductor has already been cut or damaged.

WO 2019/243193 A1 shows a device for stripping a shielded cable with a support roller arrangement having a plurality of support wheels, and a work wheel arrangement having a rolling wheel. When the device is used, the cable is clamped between the support roller arrangement and the work wheel arrangement, and both arrangements rotate around the stationary cable. The work wheel arrangement is displaceable transversely to the axis of rotation so that the rolling wheel, due to rotation, can penetrate the outer protective sheath of the cable and can cut said outer protective sheath along the circumference. In addition, the work wheel arrangement can also comprise a cutting wheel or a cutting blade that support the severing of the protective sheath. A disadvantage of this device is that the rolling wheel can cause deformation or even damage to the sensitive shielding layer, or a part thereof, in the case of softer cables. This has been found in particular in the case of cables whose shielding layer is surrounded by a shield foil that likewise has to be severed during stripping. For severing such a shield foil, corresponding pressure forces must be applied to the shield foil by the rolling wheel, which can deform or damage the underlying parts of the shielding layer, for example a shielding braid.

SUMMARY

It is one object of the present teaching to provide devices and methods by means of which stripping of cables, in particular shielded cables, can be carried out easily and reliably without adversely affecting a shielding layer by the stripping, in particular by deforming or damaging it.

According to the present teaching, this object is achieved by a device of the type mentioned at the outset, in which a plurality of perforation elements are arranged on the rolling wheel on a radially outer rolling contour such that they are distributed over the circumference, which perforation elements protrude radially by a length from the rolling contour. By means of the rolling wheel, on the one hand, the protective sheath, which is usually made of a plastics material, is effectively severed in that the rolling wheel rolling over on the cable sheath along a cutting region wears down the material of the cable sheath until finally the cable sheath no longer withstands the pressure of the rolling wheel and said rolling wheel can radially penetrate and sever the cable sheath. By contrast, the rolling wheel cannot penetrate a harder and more solid shielding layer in the cable and said layer therefore remains undamaged. On the other hand, the radially projecting perforation elements ensure that the local pressure of the rolling wheel on the shielding layer, in particular on a shielding braid of a shielding layer, remains low, thereby preventing any disadvantageous deformation or even damage to the shielding layer. Moreover, the perforation elements also ensure that any shield foil that is present is perforated and can then easily be removed from the cable along the perforation. In this case, the perforation elements penetrate only slightly into an underlying shielding braid, so that said shielding braid is not damaged. The pressure force of the rolling wheel required for this can be easily generated and controlled by corresponding adjusting means, for example by springs or corresponding actuating drives.

In an advantageous manner, the length and/or position of the guide are adjustable, for example, by means of limiting elements and/or adjusting screws. This allows the device to be easily adapted to different cable thicknesses.

In order to support the severing of the protective sheath of the cable, the work wheel arrangement additionally comprises a cutting wheel that is mounted on the work wheel guide so as to be rotatable about a cutting wheel axis, which cutting wheel has a radially outer cutting edge or a cutting blade arranged on the work wheel guide. In this case, the clamping region is formed between the at least two support rollers, the rolling wheel and the cutting wheel. The cutting wheel actively cuts into the protective sheath and thus facilitates the radial penetration of the rolling wheel into the protective sheath.

It is advantageous in this case if the radially outer rolling contour of the rolling wheel is arranged closer to the axis of rotation than the radially outer edge of the cutting edge of the cutting wheel. It can thus be achieved that the cutting edge of the cutting wheel does not come into contact with the shielding layer, in particular with a shielding braid of the shielding layer, during the stripping process and cannot damage said shielding layer.

In order for the perforation elements to reliably perforate a shield foil, but not to penetrate too far into a shielding braid of a shielding layer, it is preferably provided that the length of the perforation elements is between 0.02 mm and 0.5 mm.

In order to be able to use the rolling wheel for different cables and to achieve the most uniform possible perforation patterns along the circumference, it is advantageously provided that two perforation elements adjacent in the circumferential direction are arranged spaced apart from one another in the circumferential direction by a perforation increment, the perforation increment being in a range

[Un,Un+1],
n being a natural number between 2 and 15, preferably between 2 and 10, and U indicating a circumferential length on a radius about the axis of rotation on which the perforation elements are to produce perforations when the device is used. The perforation increment is preferably selected as centrally as possible in this range.

If the work wheel guide has an eccentric weight distribution with respect to the axis of rotation, as a result of which a centrifugal force acts on the work wheel guide when the rotation base with the work wheel guide arranged on the rotation base via the guides rotates about the axis of rotation, the required pressing force for severing the protective sheath can be brought about in a simple manner by the acting centrifugal force. This can be influenced and controlled easily and reliably by the weight distribution and/or the rotational speed. In this case, no adjusting means, such as tension springs or actuating drives, are required to generate the pressure force.

The device is used for stripping a cable having an outer protective sheath, the end of the cable to be stripped being clamped in the clamping region between the rolling wheel of the work wheel arrangement and the at least two support rollers of the support roller arrangement by applying a pressure force, the unit formed of the work wheel arrangement and the support roller arrangement rotating around the cable by rotation of the rotation base, and the rolling wheel and the at least two support rollers rolling over on the cable, and the work wheel guide having the work wheel arrangement being displaced in the guide direction toward the axis of rotation, so that the rolling wheel radially penetrates the protective sheath of the cable in a cutting region produced by the roller contour and severs the protective sheath of the cable along the circumference. The displacement of the work wheel guide having the work wheel arrangement advantageously takes place by means of the pressure force that is preferably brought about by an acting centrifugal force.

During stripping, it is preferably provided that the rolling wheel radially penetrates the protective sheath of the cable until the rolling contour reaches a shielding layer in the cable. If the shielding layer comprises a shielding braid and a shield foil surrounding the shielding braid, the rolling wheel preferably radially penetrates the cable during stripping until the rolling contour reaches the shield foil in the cable, whereby the shield foil is perforated over the circumference thereof by the perforation elements of the rolling wheel. In this way, stripping and at the same time perforating of the shield foil can be achieved, which shield foil can then be easily pulled off along the perforation with the protective sheath removed.

In order to be able to monitor the stripping process easily, it can be provided that the shielding braid of the cable to be stripped is electrically contacted by means of an electrical test contact, the test contact being electrically connected to the rolling wheel, and a measuring device and an electrical continuity check being used to check whether the rolling wheel comes into contact with the shielding braid during stripping and the stripping process is ended in the event that contact is identified. For the electrical continuity check, for example, a required electrical voltage can be applied between the test contact and the rolling wheel.

For quality assurance of the stripping process, it can also be provided that the shielding braid of the cable to be stripped is electrically contacted by means of an electrical test contact, and the test contact is electrically connected to the cutting wheel or the cutting blade, and a measuring device and an electrical continuity check are used to check whether the cutting wheel or the cutting blade comes into contact with the shielding braid during stripping. In this way, cables in which the cutting wheel or the cutting blade were in contact with the shielding braid during stripping can be eliminated.

DETAILED DESCRIPTION

The device for stripping a cable4shown by way of example inFIGS.1and2has a preferably plate-shaped rotation base2which is rotatable about an axis of rotation1and on the front of which there is arranged a support roller arrangement20consisting of a plurality of support rollers3, for example a pair of support rollers3as in the embodiment shown. Each support roller3is mounted rotatably about a support roller axis3′ on the rotation base2. In the use of the device, the rotation base2rotates about the axis of rotation1. For this purpose, the rotation base2is driven to rotate in a predetermined direction of rotation about the axis of rotation1.

The rotation base2can be connected, for example, via a shaft19to a drive (not shown), for example a motor or a combination of a motor and a transmission, that drives the rotation base2.

The support roller axes3′ of the support rollers3are preferably arranged parallel to the axis of rotation1of the rotation base2and have a radial distance A (e.g.FIG.3) to the axis of rotation1, which radial distance is selected in relation to the diameter of a cable4to be stripped in such a way that the cable4arranged on the support rollers3is oriented centrally relative to the axis of rotation1, i.e., the longitudinal axis of the cable4coincides with the axis of rotation1. The diameters of the support rollers3and their radial distances A do not necessarily have to be the same. Optionally, the radial distance A of the support rollers3on the rotation base2can be adjusted in order to be able to adjust the device to cables4of different diameters. However, the rotation base2can also be changed to adapt to different cables4. During the stripping of the cable4, however, the position of the support rollers3remains unchanged in relation to the rotating rotation base2, the support rollers3moving with the rotating rotation base2around the cable4and rolling on the outer sheath thereof.

A preferably plate-shaped work wheel guide5is arranged on the rotation base2and is displaceable relative to the rotation base2in a guide direction6running transversely, preferably perpendicularly, to the axis of rotation1. The work wheel guide5can for example be connected to the rotation base2via one or more guides7. A guide7can be designed as a linear guide, as shown inFIGS.1and2. A linear guide can be designed as a slot guide in which sliding bodies are displaceably arranged in guide slots. However, guides7of any other design can also be used. Optionally, the length of the guides7can also be adjusted and/or limited, for example via adjustable limiting elements (such as adjusting screws), in order to restrict the possible range of movement of the work wheel guide5relative to the rotation base2. Usable guides7and corresponding limiting elements are sufficiently known to a person skilled in the art and therefore do not have to be described in more detail. When designing the guides7, sufficient precision of movement must be ensured.

The rotation base2can optionally be provided with a central recess21into which the end of the cable4can protrude or through which the cable4can protrude so that the space required by the rotating parts can be minimized. The recess21is only indicated schematically inFIG.1, but it can also be made significantly deeper and can also be continuous through the rotation base2. In the latter case, the drive of the rotation base2is to be designed in a suitable manner.

A work wheel arrangement10is arranged on the work wheel guide5, the work wheel arrangement10comprising at least one rolling wheel8. In an advantageous embodiment, the work wheel arrangement10additionally also comprises a cutting wheel9. In a preferred embodiment, the work wheel arrangement10comprises a rolling wheel8and a cutting wheel9. Such an embodiment is shown inFIGS.1and2.

As a result of said embodiment of the device, a clamping region24is formed around the axis of rotation1and between the at least two support rollers3and the rolling wheel8, and optionally the cutting wheel9, which clamping region can, by displacing the work wheel guide5in the guide direction6relative to the rotation base2, be enlarged and reduced depending on the displacement direction. The cable4to be stripped is arranged in said clamping region24and clamped between the at least two support rollers3and the rolling wheel8, and optionally the cutting wheel9, when the device is used. As a result of the rotation of the rotation base2, the support roller arrangement20with the support rollers3and the work wheel guide5with the rolling wheel8, and optionally the cutting wheel9, rotate around the clamping region24. If a cable4is arranged and clamped in the clamping region24, the support rollers3and the rolling wheel8, and optionally the cutting wheel9, roll over on the outer sheath of the cable4. The cable4does not also rotate here.

The rolling wheel8and cutting wheel9(if present) are arranged so as to be rotatably mounted on the work wheel guide5and for this purpose have a rolling wheel axis8′ and cutting wheel axis9′, preferably arranged parallel to the axis of rotation1. With respect to the axis of rotation1(and the resulting position of the cable4in the device), the work wheel arrangement10is arranged in the guide direction6on the side opposite the support rollers3, so that the cable4resting on the support rollers3can be clamped between the support rollers3and the work wheel arrangement10by displacing the work wheel arrangement10in the guide direction6. In the embodiment according toFIG.1, the cable4is clamped between the support rollers3and the rolling wheel8and the cutting wheel9of the work wheel arrangement10. When the rotation base2now rotates about the axis of rotation1, the support rollers3, the rolling wheel8, and the cutting wheel9(if present) roll over on the sheath of the cable4, i.e. on its protective sheath14, along a cutting region15in the circumferential direction.

It should be noted that the cutting region15does not have to be a cutting line, but rather generally identifies a region extending in the axial direction of the cable4in which the protective sheath14of the cable is to be severed. As will be explained in the following, the action of the rolling wheel8on the cable4also extends in the axial direction laterally beyond the region of direct contact between the rolling wheel8and protective sheath14, so that the rolling wheel8and the cutting wheel9can also be arranged in the axial direction slightly offset to one another laterally (as shown inFIG.2). The axial region that is affected by the action of the rolling wheel8is referred to as the cutting region15in connection with the present teaching.

The cable4can also be secured in a fixed (i.e. not rotating with the rotating parts of the device) clamping device22, which is only indicated schematically inFIG.2. The clamping device22can be arranged very close to the work wheel guide5, in order to press the cable4into its round cross-sectional shape and to hold it therein during processing. This is particularly advantageous with softer cables4. If necessary, the free end of the cable4can also be held with a corresponding inner clamping device22′ (this is also indicated schematically inFIG.2), wherein the inner clamping device22′ can be mounted on the rotation base2, for example by means of a ball bearing (not shown). Thus, the inner clamping device can be stationary during the rotation of the moving parts and can center the cable4. The inner clamping device22′ can then also be used, for example, to pull the separated part of the protective sheath44off the cable4after processing.

At the end of the work wheel guide5that is in relation to the axis of rotation1and in the guide direction6opposite the work wheel arrangement10, a weight16is provided in the embodiment according toFIGS.1and2that gives the work wheel guide5an eccentric weight distribution with respect to the axis of rotation1. The eccentric weight distribution can also be ensured without additional weight16solely by the shape of the work wheel guide5.

When the rotation base2rotates about the axis of rotation1with the work wheel guide5arranged thereon via the linear guides7, a centrifugal force Fzfacts on the work wheel guide5in the guide direction6on account of the eccentric weight distribution, so that the work wheel guide5having the work wheel arrangement10is pressed against the outer surface of the cable4(or against the counterforce applied by the support rollers3). The pressure force of the working arrangement10against the cable4can thus be controlled structurally via the design of the weight distribution of the work wheel guide5, for example by means of the weight16, and procedurally via the rotational speed. If necessary, the weight16can be designed to be exchangeable or changeable in order to vary the pressure force. The work wheel guide5can optionally be pretensioned by means of tensioning means, such as springs, into the “open” position, in which the support rollers3and the work wheel arrangement10are farthest apart from each other, the work wheel arrangement10then only coming into contact with the protective sheath14of the cable4when the rotation base2of the device rotates sufficiently quickly and the work wheel guide5, due to the centrifugal force Fzf, acts sufficiently strongly against the force applied by the tensioning means. Alternatively or additionally, the drive of the rotating parts can be controlled in such a way that the weight16is arranged at the top at a standstill, so that the work wheel arrangement10is automatically pressed downwards (i.e., into the open position) by its own weight.

However, the pressure force can also be applied by corresponding actuators, such as a spring or an actuating drive. In this case also, no eccentric weight distribution of the work wheel guide5is required. A combination of an actuating drive and the effect of a centrifugal force Fzfis also conceivable.

In connection with the present disclosure, the “front side” is the side of the device on which the cable4to be stripped is to be arranged, i.e. the side shown inFIG.1or the right side inFIG.2. The term is only used for understanding and orientation and is not to be interpreted restrictively. In particular, it would also be possible to “reverse” the arrangement of rotation base2and work wheel guide5, so that the work wheel guide5with the elements arranged thereon is arranged opposite the front side, i.e., “behind” the rotation base2, the cable4then being inserted through a central opening provided in the rotation base2in order to come into contact with the work wheel arrangement10and support roller arrangement20. If necessary, the work wheel arrangement10can also be arranged in the axial direction between the rotation base2and the work wheel guide5, or it can be arranged in a protected manner in an interior of the work wheel guide5. Implementation of the design changes required for such alternative embodiments is within the ability of an ordinary person skilled in the art.

As shown inFIG.4, the cable4consists substantially of a conductor11or a plurality of conductors11which are arranged in a wire arrangement12forming the core of the cable4. The individual conductors11can be electrically insulated from one another or towards the outside, it being possible for further layers to be provided depending on the cable type, for example in order to separate individual conductor bundles from one another in the wire arrangement12. A shielding layer13, for example a thin metal foil, for example made of aluminum or copper, or a filigree shielding braid25made of metal wire, is provided around the wire arrangement12. If necessary, the shielding layer13can also consist of a plurality of such layers. Such shielding layers13are sufficiently known in the technical field in a wide range of embodiments and therefore do not have to be described in more detail in this case. Since the shielding layer13usually consists of comparatively costly material(s), the manufacturers endeavor to make this layer as thin as possible. The shielding layer13is therefore usually very sensitive, in particular to mechanical loads. The protective sheath14is arranged as the outermost layer of the cable4around the shielding layer13, protects the unit formed of the wire arrangement12and shielding layer13against external influences, and serves as electrical insulation of the cable4.

The shielding layer13can also comprise a shield foil26that surrounds a shielding braid25or a metal foil (or both). The shield foil26is usually embodied as a plastics material film, usually as a plastics material film that is metal-coated (either by vapor deposition of a metal layer on the plastics material foil or by laminating a metal foil with a plastics material film).

For stripping the cable4, the protective sheath14is to be removed along an axial region of the cable4, usually in the region of the axial free end of the cable4. If the shielding layer13also comprises a shield foil26, the shield foil26is also to be removed in order to expose the shielding braid25or the metal foil (or both) in this region for electrical contacting. The shielding braid25or the metal foil (or both) should not be deformed too much or even damaged during this process.

The rolling wheel8and the cutting wheel9have different cross sections in a plane parallel to their axis of rotation8′,9′, as indicated inFIG.3by hatching. In particular, the cutting wheel9forms a radially circumferential, radially outer cutting edge17, while the rolling wheel8has a blunter edge geometry radially on the outside than the cutting wheel9, this edge geometry being referred to as a rolling contour18in connection with the present disclosure. The rolling contour18of the rolling wheel8is designed in dependence of the material parameters of the protective sheaths14to be cut and in dependence of the adjusted or adjustable pressure forces in such a way that the rolling wheel8does not penetrate the material of the protective sheath14in a cutting manner but only presses the material and displaces it a little. In contrast to this, in connection with the present teaching, a “cutting blade” is viewed as a contour which, under these conditions, penetrates the material of the protective sheath14in a cutting manner. The cutting wheel9therefore tapers at the radial end to the cutting edge17, while the rolling wheel8at the radial end has an axial width as the rolling contour18, which axial width is adjusted to the material parameters of the protective sheath14.

The continuous load of the “rolling” of the protective sheath14carried out by the rolling wheel8having the rolling contour18rotating around the cable4impairs the quality of the material of the protective sheath14in the cutting region15and “wears down” the material. As a result, the rolling wheel8radially penetrates the protective sheath14by displacing the material of the protective sheath14. If a cutting wheel9is additionally provided, the protective sheath14can also be easily severed by the cutting wheel9due to this “rolling,” which supports the stripping. However, the protective sheath14can also be severed solely by the rolling wheel8.

Since the shielding layer13is made of a different material (generally metal) than the protective sheath14(generally plastics material), the pressure of the rolling contour18rolling on the shielding layer13only causes a lower deformation than is the case with the material of the protective sheath14. As soon as the rolling contour18thus reaches the region of the shielding layer13, the rolling wheel8presses in less deeply. Ideally, the further movement of the work wheel guide5with the rolling wheel8in the guide direction6is stopped when the rolling contour18reaches the shielding layer13. This can be achieved by suitably designing the rotational speed of the rotation base2and/or the eccentric weight distribution of the work wheel guide5.

If the work wheel arrangement10comprises a cutting wheel9, it is advantageous if the cutting wheel9, which of course moves with the rolling wheel8as part of the work wheel arrangement10, does not come into contact with the shielding layer13. The shielding layer13therefore cannot be cut by the cutting wheel8and cannot become damaged as a result.

For this purpose, it can be provided that the outer radial edge of the rolling contour18is arranged a little closer to the axis of rotation1than the outer radial edge of the cutting edge17. This is shown inFIG.3. The difference between the (larger) distance D between the cutting edge17and the axis of rotation1and the (smaller) distance d between the rolling contour18and the axis of rotation1is very small and can, for example, be between 5% and 50%, preferably between 10 and 20% of the layer thickness of the protective sheath14to be severed. For example, the difference (D-d) can be between approximately 50 μm and 200 μm, in particular approximately 100 μm.

The difference (D-d) can be set by design in different ways. In an embodiment that is very easy to manufacture, for example, the rolling wheel8and the cutting wheel9can each have different outer radii, the outer radius R of the rolling wheel8being larger than the outer radius r of the cutting wheel9, as shown inFIG.3. This makes it possible to arrange the axes of rotation8′,9′ of the rolling wheel8and the cutting wheel9at the same radial distance from the axis of rotation1, which is structurally advantageous. In another possible embodiment, the axes of rotation8′,9′ of the rolling wheel8and of the cutting wheel9can lie on different diameters. In this case, the outer radii r, R can also be the same.

Possible radii, distances, and contours are shown schematically and clearly inFIG.3. The cable4arranged coaxially on the axis of rotation1is kept in position between the two support rollers3and the work wheel arrangement10formed of the rolling wheel8and cutting wheel9pressing against the support rollers3on account of the acting pressure force, for example the centrifugal force Fzf, while the rollers or wheels rotate around the cable4due to the rotation of the rotation base2. In the process, the rolling wheel8rolls and displaces the material of the protective sheath14and thus very quickly leads to targeted material fatigue so that the material can be cut at this point by the “subsequent” cutting wheel9. The rolling wheel8then radially penetrates this cut and displaces and wears down the material even more.

As soon as the rolling wheel8has reached the material of the shielding layer13, a further displacement and penetration into the material is prevented due to the higher strength of the shielding layer13and wire arrangement12, and the rolling wheel8rolls over on the surface of the shielding layer13without further penetrating the cable4and prevents the shielding layer13from coming into contact with the cutting wheel9. This position is shown inFIG.3by the dashed outline of the rolling wheel8and cutting wheel9. It is shown in a highly exaggerated manner that the cutting wheel9does not touch the shielding layer13. The drive of the device can then be switched off, the cable4removed, and the separated part of the protective sheath14can be pulled off.

The design of the rolling contour18, in particular the axial width and the geometry at the radial end of the rolling wheel8, is either known or can simply be carried out by corresponding tests with cables4to be stripped.

In particular in the case of cables4having a shield foil26in the shielding layer13, a high pressure force of the rolling wheel8on the cable4can be necessary in order to bring about severing of the shield foil26. In this case, for example, the rolling wheel8would have to penetrate the cable4until the shield foil26is severed by a cutting wheel9. However, this could be accompanied by greater deformation or even damage to the other parts of the shielding layer13, in particular of a shielding braid25, which is to be avoided. In order to provide a remedy for this problem, perforation elements27are provided distributed over the circumference of the rolling wheel8on the rolling contour18of the rolling wheel8and protrude radially by a predefined radial length L from the radially outer rolling contour18of the rolling wheel8. This is shown on the basis of advantageous embodiments inFIGS.5-8.

FIGS.5and6show an embodiment of a rolling wheel8having perforation elements27, the perforation elements27being an integral part of the rolling wheel8, i.e., being formed integrally with the rolling wheel8. For this purpose, the rolling wheel8can be injection-molded, for example from plastics material (such as PEEK (polyether ether ketone) or a filled or fiber-reinforced plastics material), and then can be reworked, in particular to ensure the desired length L. However, the rolling wheel8can also be made of metal (steel or stainless steel), and the perforation elements27can be machined by means of a cutting production method. Other known production methods for producing the perforation elements27, such as a wire erosion method or spark erosion method, are also conceivable here.

In the embodiment according toFIGS.7and8, the rolling wheel8is made of plastics material (such as PEEK (polyether ether ketone) or a filled or fiber-reinforced plastics material) or metal (steel or stainless steel), with needles being inserted into the rolling contour18as perforation elements27. The needles are produced, for example, from steel or stainless steel. The needles can have a diameter of 0.1 mm to 0.5 mm. In order to achieve a precise length L of the perforation elements27, the needles used can be ground to the desired length L after insertion.

The shape of the protruding perforation elements27can be tapered, for example in a conical or pyramid-shaped manner, but can also be prismatic or cylindrical.

The length L with which the perforation elements27project radially from the rolling contour18is preferably between 0.02 mm and 0.5 mm. It can thus be achieved that the perforation elements27perforate a shield foil26, typically having thicknesses of 10 to 100 μm, but do not damage other underlying parts of the shielding layer13, in particular a shielding braid25. No large radial pressure forces are required for the perforation, which significantly reduces or entirely prevents the risk of undesirable deformations and damage to a shielding braid25or other parts of the shielding layer13. If no shield foil26is present, the perforation elements27penetrate a shielding braid25without deforming it significantly or disadvantageously.

By means of a rolling wheel8having perforation elements27, on the one hand, the protective sheath14can be simply and reliably cut through as described above. If the rolling wheel8reaches the shielding layer13, any shield foil26that is possibly present is perforated over the entire circumference of the cable4with few revolutions of the rolling wheel8. Thereafter, the protective sheath14separated off can be easily removed with the shield foil26, the shield foil26being torn off cleanly at the perforation. In this way, the stripping can be achieved with lower pressure forces and penetration depths of the rolling contour18into the cable4, whereby deformations of sensitive parts of the shielding layer13, such as a shielding braid25, can be avoided.

The distance in the circumferential direction between two adjacent perforation elements27on the rolling wheel8(perforation increment P) is preferably selected such that, with repeated circling of the cable4during stripping, the perforation of the shield foil26produced does not result in excessively large gaps between perforations30or in perforations30(accumulations of perforations) that are too close to one another. Both can lead to an unclean separation of the shield foil26, which can lead to the formation of tabs and to a frayed separation point. This can impair the quality of the stripped cable4and further use thereof.

InFIG.9, for example, an accumulation of perforations30, produced by the perforation elements27, on a shield foil26(shown here unwound for illustration) is shown. An accumulation31of perforations30and larger gaps32between perforations30can be seen over the circumferential length U of the shield foil26. For better understanding, the perforations30are shown inFIG.9with different geometric figures, each geometric figure corresponding to a circling of the cable4with the rolling wheel8. Said accumulations31and gaps32result from an unfavorably selected perforation increment P on the rolling wheel8. The perforation increment P is understood to mean the arc length between two adjacent perforation elements27on the rolling wheel8.

To avoid such accumulations31or gaps32, the perforation increment P is selected in the range

[Un,Un+1],
where n is a natural number. U designates the circumferential length on the radius around the axis of rotation1in the region of the cable4on which the perforations30are to be produced. Usually, this is the radius on which the shield foil26to be perforated is located. n is advantageously selected in such a way that, in the case of the expected number of times the cable4is to be circled with the rolling wheel8for perforation, the distance between adjacent perforations30in the circumferential direction is not less than 1 to 3 mm, because also a perforation increment P that is too small can lead to unclean separation. For conventional cables4, the natural number n is between 2 and 15, preferably between 2 and 10. If the perforation increment P is selected approximately in the center of this range, this results in a continuous application range of the rolling wheel8for different cable diameters in a certain diameter range, and it is possible to avoid accumulations31and/or gaps32.

A targeted perforation pattern with perforations30on a shield foil26without such accumulations31and/or gaps32is shown inFIG.10for comparison.

However, it is of course also possible to use different rolling wheels8for different cables4, or also for different cable diameter ranges, wherein the perforation increment P of the perforation elements27of the rolling wheel8is adapted to the particular cable4.

For quality monitoring of the stripping process, an electrical continuity check can also be used, as explained with reference toFIG.11.FIG.11shows only the cable4, but not the other parts of the device, for example as shown inFIGS.1and2. For the continuity check, a shielding braid25of the cable4is electrically contacted by means of a test contact40. The test contact40can be embodied as an electrically conductive blade or brush and contacts the shielding braid25in the region of the axial end of the cable4. However, the test contact40can also be embodied as a plate that is axially spaced apart from the cable end and is arranged in the region of the shielding braid25. The resulting air gap between the plate and the shielding braid25can be bridged by supplying ionized air, so that a sufficient electrical connection results between the plate and the shielding braid25. The test contact40is electrically connected to the cutting wheel9via a test line41. For this purpose, the cutting edge9must be electrically conductive. An electrical connection between the test contact40and the cutting wheel9can then be identified via a measuring device42, for example by applying a test voltage and measuring a current. In the case of a detected electrical connection, the cutting wheel9would have had undesired contact with the shielding braid25, which is recognized in this way and allows further use of the cable to be prevented.

A second test contact45(dashed inFIG.11) can also be provided, and, as described above, should also contact the shielding braid25. This second test contact45is connected to the first test contact40via a second test line44. In this way, an electrical continuity check between the first test contact40and the second test contact45can be carried out via a second measuring device43in order to ensure that the first test contact40contacts the shielding braid25. The sequence of the check can be carried out in such a way that the first and second test contacts40,45and a continuity check are first used to determine whether the first test contact40electrically contacts the shielding braid25and then the first test contact40is used to continuously check whether the cutting wheel9touches the shielding braid25.

With such a continuity check, it is also possible to recognize if the rolling wheel8reaches the shielding braid25or the shield foil26. If the rolling wheel8is designed to be electrically conductive, it is possible, as explained above, to use a test contact on the shielding braid25that is electrically connected to the rolling wheel8to determine that the perforation elements27of the rolling wheel8penetrate the shielding braid25. If this is determined, the stripping process of the cable4can be stopped. If a shield foil26is also present in the cable4, it is thus ensured at the same time that the shield foil26was also perforated in the desired manner by the perforation elements27.

Due to the simple and stable construction, the device according to the present teaching can be operated at high speeds, for example between 100 rpm and 5000 rpm. The process of stripping a cable4can thus be carried out very quickly, with only a few seconds being required for a stripping process. It is also not necessary to measure the severing of the protective sheath14with complex and error-prone devices, since severing the desired parts of the shielding layer13is in any case ruled out with the device according to the present teaching.

InFIG.3, the rolling wheel8and the cutting wheel9are shown spaced relatively far apart for reasons of clarity. However, in order to securely clamp the cable4between the work wheel arrangement10and the support rollers3, it is preferred to arrange the rolling wheel8and the cutting wheel9close to one another, it being possible for the circumferential contours of the two wheels to optionally also overlap if the wheel profiles allow this. Wheel profiles of the rolling wheel8and cutting wheel9which allow overlapping are shown inFIG.2, for example. This arrangement makes use of the property of the rolling wheel8, which deforms and wears down the material of the protective sheath14not only in direct contact, but also in a specific region laterally of this contact.

In the embodiment according toFIG.12, the work wheel arrangement10has only one rolling wheel8having the perforation elements27, which rolling wheel rolls over on the cable4in such a way that it presses against the protective sheath14and fatigues the sheath material until it can no longer offer sufficient resistance to penetration by the rolling wheel8. The rolling wheel8penetrates further and further into the material of the protective sheath14until it has reached the shielding layer13and the perforation elements27perforate a shield foil26(if present).

FIG.13shows a further alternative embodiment of the work wheel arrangement10.FIG.13shows that not only wheels can be used in the work wheel arrangement10, but that it can also comprise other, non-rolling elements. In particular,FIG.13shows a rolling wheel8which has perforation elements27and which is combined with an “off-center” cutting blade23. The arrangement of the cutting blade23is selected such that, when the device is functioning properly, said cutting blade cannot come into contact with parts of the shielding layer13that must not be damaged. In this case, the cutting blade23is arranged on the work wheel guide5in a stationary (but possibly adjustable) manner when the device is used. The cutting blade23is arranged in such a way that, when the work wheel guide5is moved in the guide direction6, the cutting blade23cannot touch the shielding layer13or certain parts thereof. Due to the known geometry of the cable4, this is easy to accomplish. The cutting blade23supports the severing of the protective sheath14with the rolling wheel8.