DE102017221115B3 - Method and device for stripping a cable - Google Patents

Abstract

For stripping a conductor having a lead core and a surrounding sheath of a softenable material, a portion of the sheath is removed from the lead core, in which the sheath is heated in the region of the subsection so that the material of the sheath merely softens. Subsequently, the section is mechanically removed by a stripping tool.

Description

The invention relates to a method and an apparatus for stripping a line.

In the assembly of electrical lines, it is regularly necessary to remove an insulating jacket in an end region of a line core. The insulating jacket is typically extruded on the lead core and therefore typically has high adhesion to the lead core. This adhesion between the sheath and the core must be overcome during stripping. In some applications - depending on the material of the shell or the material pairing between the shell and the outermost layer of the core or in dependence on the specific structure of the line - a stripping difficult, so a reliable automatic stripping is not always guaranteed.

Specifically, problems arise when the line is a shielded line and the outermost layer of the line core is formed by a shield, especially when formed by a helical or braid shield. In both cases, the shield is generally formed by a plurality of individual wires, which are either helically arranged running around the core line or also intertwined with each other. In this case, the sheath material can penetrate between the individual wires, whereby the adhesion is increased. In the case of such shielded lines, stripping problems occur, in particular when polyurethane (PU) is used as the jacket material. Especially in this case, the material of the jacket literally sticks to the lead core, especially to the shielding.

From the DE 10 2015 112 320 B3 discloses a method for stripping, in which a portion of an insulating sleeve first softened by means of a heated separating jaw and then separated from the separating jaw.

From the DE 25 05 750 A1 is a method for stripping a stripline to remove, which has insulating films bonded by an adhesive. For stripping the insulating films and thus the adhesive are heated in stripped area, so that the insulating films can be removed.

From the DE 39 15 286 A1 is to remove a device for automatically processing wire lines, in which stripped wire ends are severed by means of electrodes in a welding operation and secured against splitting.

According to the DE 11 35 537 A For example, instead of heating the insulation, it is suggested to use swelling agents to soften the insulation before separation.

According to the DD 1 03 104 A1 heated stripping jaws are provided for stripping.

Proceeding from this, the present invention seeks to provide a simple and reliable stripping in provided with a shield (sheath) lines.

The object is achieved by a method for stripping a line, wherein the line is designed as a sheathed cable with a line core and a surrounding sheath. The jacket has an inner side oriented towards the core and a side facing away from the core. The material of the jacket is generally softenable under the influence of temperature. During stripping, a portion of the jacket is removed from the lead core. For this purpose, the jacket is heated in the region of the partial section, in such a way that the material of the jacket is merely softened in the partial section. In a subsequent immediately following process step, the subsection is then mechanically removed by a stripping tool.

The stripping process is thus designed as a two-stage process, in which first the subsection is heated and then mechanically removed, in particular stripped off.

This embodiment is based on the consideration that the adhesion between the shell and the core line is done by a kind of bonding between the inside of the shell and the outer layer of the core line. Especially if the outermost layer is a metallic shield, this bonding is not a classic chemical bond between the two materials of the shell and the shield, but merely a so-called adhesion bonding on purely physical processes. This is based on the fact that great bonding forces are formed between surfaces which lie very close together and in particular smooth surfaces, which lead to the high adhesion which is unfavorable for the stripping.

The targeted heating of the material of the shell at least on the inside of the material of the jacket is softened. Softening is generally understood to reduce the hardness of the material as compared to the unheated state. Preferably, the solid state still remains. Alternatively, the material can also change to a highly viscous state, but retaining the shape. By the Warming is caused by a movement on molecular or atomic motion. As a result, the binding forces are reduced, which leads to a significantly reduced adhesion in the heated section between the jacket and core core.

In the subsequent second process step, the partial section is then mechanically removed in a conventional manner. Due to the reduced adhesion, a reliable and safe, in particular automated, stripping, especially within a cable assembly plant, is made possible by this two-stage process.

The conductor may be a wire, that is to say a conductor provided with core insulation as a conductor core. The line core itself preferably has a line structure consisting of a plurality of individual components, such as cores, electrical data lines with and without shielding, optical components, etc.

According to the invention, the line is a shielded line in which the line core has a shield as an outermost layer oriented to the jacket. This is in particular formed from a multiplicity of individual wires which form a braided shield or a helical shield in particular. The above-explained two-stage stripping process leads in particular to such shielded lines to a significantly improved stripping.

The heating of the section can be done for example by hot air or by electromagnetic radiation, such as infrared radiation and in particular from the outside. Furthermore, a resistance heating can take place, either from the outside or by an internal electrically conductive component of the line is energized.

The heating is carried out inductively according to the invention by an in-line component is heated inductively, thereby heating the jacket. The inductive heating leads to a targeted heat input, especially at the interface between the jacket and the core. Inductive heating leads to targeted heating of the shielding, especially when using shielded lines, so that the surface areas are immediately heated towards the inside of the jacket. The softening of the jacket material therefore takes place purposefully in the region of the adhesive seat between the core and the jacket material.

Conveniently, the heating is controlled so that on the inside of the shell, a temperature increase in the range of at least 20 K and at most of 250 K is reached. The temperature is generally chosen so that the material is merely softened but not chemically decomposed or liquefied. Except for softening, the mantle essentially retains its integrity and shape. In particular, it still has sufficient hardness in the part to be stripped, so that it can still be removed mechanically in the subsequent step.

Preferably, the temperature increase is at least 50 K. The maximum temperature increase is preferably still at the highest 150 K.

In an expedient development of the jacket is heated and softened only in the area of the inside. The outside therefore experiences no or at least no significant increase in temperature. This is particularly possible in connection with the inductive heating, since heat is introduced specifically on the inside. In this case, in particular, the poor heat conduction of the material of the shell is exploited.

The outside of the shell is therefore preferably not softened. An outer annular portion, for example half or even one third of the wall thickness of the shell, therefore preferably retains - at least substantially - its original hardness. After heating, therefore, the jacket has an outer harder annular skirt portion and an inner softer annular skirt portion. As a result, the removal of the subsection is supported in the subsequent mechanical stripping.

Overall, the heating is preferably controlled such that no temperature increase takes place on the outside of the jacket or at most a temperature increase which is less than 40 K and preferably less than 20 K or less than 10K.

In addition, the jacket is preferably also heated only in the area of the partial section. It is thus considered in the longitudinal direction of the line only at a defined end portion, the heating. The areas of the jacket adjacent to the portion to be stripped are not heated. At most, a transition region is still heated by the heat conduction within the material.

The stripping tool is, as already mentioned, preferably a conventional stripping tool. This usually has a cutting element which cuts into the jacket, so that the part to be stripped is separable. The stripping tool cuts in particular to the entire circumference in the mantle.

Conveniently, the stripping tool does not fully intersect the shell in the radial direction, i. the depth of cut of the stripping tool is less than the thickness of the shell. By this measure, a violation of the outermost layer of the core line, in particular the shield is reliably prevented. Due to the softened jacket material, however, a simple removal of the line section is made possible at the same time. A remaining material bridge at the interface between the core and the cladding can be easily removed.

Conveniently, the removal of the subsection is performed by the stripping tool itself, i. this and the conduit are relative to each other in the longitudinal direction of the conduit e.g. moved with retracted cutting element, so that the cutting element subtracts the separated portion of the jacket from the core line.

The softenable material of the shell is generally preferably made of a thermoplastic material. In this case, all conventional insulating materials, which are used for conductor coats, are used. Specifically, the material of the jacket is a polyurethane (PU).

The object is further achieved by a device for stripping a line. In this case, the device has a heating station with a control device and with a receptacle for a part of the line, wherein the control device is set up such that during operation the jacket is heated in a partial section, so that only a softening of the material of the partial section takes place. Furthermore, the device comprises a stripping station which is arranged downstream of the heating station and which has a stripping tool for mechanical stripping of the heated section.

The heating station preferably has a heating power of greater than 500 watts. Preferably, the heating power is in a range of greater than 1 kW and especially up to 30 kW. The maximum heating power is typically measured according to the diameter of the line to be stripped. For most applications, the upper limit of heating power is 15 kW. The heating power is generally sized large enough to achieve a sufficiently fast stripping work cycle, so that the heating station can be integrated into a conventional cable assembly line as an additional processing station, such that the heating station carries out the heating of the section in the same work cycle, which is predetermined for example by a cutting station or by the subsequent stripping station.

The heating station has an induction coil for inductive heating of the section. The induction coil, in turn, expediently comprises a waveguide, which, in an expedient configuration, continues to flow through a cooling medium during operation. The induction coil or the waveguide is therefore connected via a connection with a coolant supply in order to enable a desired active cooling of the induction coil during operation. This active cooling is particularly advantageous for induction coils with high heat output.

By means of the induction coil, high-frequency magnetic fields are generally generated which induce a current flow in the electrically conductive component, in particular in the shielding. This (induction) current typically moves over the shield wires in a circle around a longitudinal axis of the line. As a result of the electrical resistance heats up the shield and therefore minimizes the liability exactly at the desired location.

A prerequisite for the circulating current flowing induction current is that the individual individual wires of the shield closely abut each other, otherwise there is too high contact resistance between the individual wires and no current can flow. Due to the extruded jacket, the individual wires are pressed together with high contact pressure, so that the generation of the circular induction current is possible.

In order to achieve effective heating, the coil is expediently set at a frequency in the range of greater than 100 kHz and preferably up to, for example, a maximum of 10 MHz or even a maximum of 5 MHz. The choice of frequency depends on the properties of the electrical component to be heated, such as choice of material and thickness.

The particular advantage of this inductive heating is the fact that it forms only in the region of the induction coil, so that selective heating is achieved only in a localized area.

In addition to the improved process reliability in a cable assembly plant, the advantage is further achieved that the subsequent conventional stripping is mechanically less stressed, so that their life is increased.

Furthermore, due to the simplified stripping in the cable and cable assembly more degrees of freedom in the design of the line structure, which affects both the constructive side of the line structure and the choice of material. It must therefore be taken less consideration for a low adhesive fit between the jacket and core and core and higher adhesion values can be taken into account, which then favorably affect, for example, a pull-out strength of the line during assembly, for example in plugs.

• 1 eine Querschnittsdarstellung einer Leitung,
• 2A eine vereinfachte Ansicht einer Heizstation zum Erwärmen eines abzuisolierenden Teilabschnitts der Leitung sowie
• 2B eine Abisolierstation, die nachfolgend zu der Heizstation angeordnet ist.

An embodiment of the invention will be explained in more detail with reference to FIGS. These show, in partially simplified schematic representations:

• 1 a cross-sectional view of a line,
• 2A a simplified view of a heating station for heating a stripped portion of the line as well as
• 2 B a stripping station located downstream of the heating station.

The in the 1 illustrated line 2 is formed as a so-called sheathed cable, which has an outer sheath 4 having a lead core 6 surrounds. The lead core has an outermost layer concentric with the mantle 4 arranged shielding 8th on, which is formed in particular in a manner not shown here as a braid or helical shield with a plurality of individual wires. The shield 8th again encloses a kind of soul soul. In the embodiment, several electrical wires are 10 shown. In principle, this line core can have different design variants. The line core has, for example, data cores which are arranged in pairs or in groups of four, shielded or unshielded. In addition, further transmission elements can be arranged as power cores (power wires) as well as optical transmission elements etc. Inside the shield 8th may also be included sub-lines, which in turn are surrounded by a sub-line jacket.

The coat 4 generally consists of a softenable, in particular thermoplastic material and especially of polyurethane. The coat 4 has an inward shielding 8th oriented inside 12 and an outer, the lead core 6 opposite outside 14 on.

The administration 2 generally extends in a longitudinal direction and is typically stored by the meter on a cable drum. As part of a confectioning typically several finishing steps such as cutting to length, stripping and abutment of contact elements, such as crimp contact elements performed.

In the 2A . 2 B are two workstations, namely a heating station 16 as well as a stripping station 18 shown. These are formed within a confectioning path as two successive stations.

First, the heating station 16 a usually cut to length, so tailored to the desired Längenmaß line 2 supplied one end ahead. The heating station 16 has a recording for this purpose 20 on, which is a tail of the pipe 2 receives. The heating station 16 also has an induction coil 22 on the record 20 is arranged around. The induction coil 22 itself in turn has at least one wound waveguide 24 on, in its operation inside a coolant K for cooling the induction coil 22 leads. The at least one waveguide 24 is connected via a connection to a coolant supply in a manner not shown here.

The heating station 16 is still a control device 26 assigned. This is optionally a control device 26 the heating station itself or to a higher-level control device that controls the entire confectioning process. Using the heating station 16 is generally a subsection 28 , namely an end portion of the shell, heated by inductive heating.

The following stripping station 18 serves for the mechanical separation of the heated section 28 , The administration 2 is therefore immediately after heating in the heating station 16 the stripping station 18 fed before the heated section 28 again cools and hardens. The stripping station 18 generally has a stripping tool 30 which typically has cutting elements, such as V or form blades, into the shell 4 cut in and create a circumferential cut. However, the knife penetrate only partially into the mantle 4 one, so only cut through a part of it, so that the underlying shield 8th not hurt.

The two-stage stripping process is as follows: First, the line with the stripped portion 28 in the recording 20 introduced. Subsequently, the subsection 28 inductively heated. Usually, a connection of the induction coil takes place here 22 for a period of time. Magnetic fields are generated via the induction coil, typically at a frequency in the range of 100 kHz to, for example, in the megahertz range. This will be in the shield 8th Currents induced, leading to heating of the shield 8th to lead. By heat conduction becomes the inside 12 of the coat 4 in the section 28 heats and softens there so that the adhesion between the material of the jacket and the shield 8th is reduced.

Subsequently, the thus prepared line 2 the stripping station 18 supplied in the stripping tool 20 a circumferential cut in the area between the section 28 and the rest of the jacket. Finally, the subsection 28 deducted. This is typically the line 2 in the direction of the arrow 32 withdrawn.

It should be emphasized that by selective inductive heating only in the area of the inside and only in the region of the part to be stripped 28 only this inside of the heating and softening is affected and the remaining or further sections of the shell, so the outside of the shell of the subsection 28 as well as to the subsection 28 subsequent remaining coat are not affected by the heating and softening and therefore continue to have the original consistency and hardness, so that the stripping in a simple manner as usual with the conventional stripping tool 30 can be reliably generated.

Claims (12)

A method of stripping a lead having a lead core and a surrounding sheath of a softenable material, the sheath having an inner side facing the lead core and an outer side, a subsection of the sheath being removed from the lead core by first disposing the sheath in the region is heated so that the material of the shell is only softened and then by the part section is removed mechanically by a stripping tool, characterized in that it is a shielded line in the line and the core line as the outermost to the shell oriented layer with a shield a plurality of individual wires, which is heated and that the portion is heated inductively. Method according to Claim 1 in which the heating is controlled such that on the inside of the jacket, a temperature increase in the range of at least 20 K and at most of 250 K, preferably in the range of at least 50 K and more preferably of at most 150 K. Method according to one of Claims 1 to 2 , in which the jacket is softened in the section only in the region of the inside. Method according to one of Claims 1 to 3 in which the outside of the jacket is not softened. Method according to one of Claims 1 to 4 in which the heating is controlled in such a way that no or at most a temperature increase of less than 40 K, preferably less than 20 K, takes place on the outside of the jacket. Method according to one of Claims 1 to 5 in that the stripping tool cuts into the shell between the section and the remaining shell. Method according to one of Claims 1 to 6 in which the stripping tool does not completely cut through the jacket in the radial direction. Method according to one of Claims 1 to 7 in which the stripping tool peels off the part to be stripped. Method according to one of Claims 1 to 8th in which the jacket is made of a thermoplastic material. An apparatus for stripping a shielded lead comprising a lead core and a surrounding sheath of a softenable material and a shield having a plurality of discrete wires as the outermost sheath oriented layer, the device comprising a heating station with a control device and with a receptacle for a part of the line, wherein the control device is set up such that in operation the jacket is heated in a partial section, so that only a softening of the material of the partial section takes place, a stripping station located downstream of the heating station and having a stripping tool for mechanically stripping the section, wherein - The heating station has an induction coil for inductive heating of the subsection. Device after Claim 10 in which the heating station has a heating capacity which is greater than 500 watts and in particular in the range of 1 kW to 30 kW. Device after Claim 10 or 11 in which the induction coil has a waveguide, which is flowed through during operation of a cooling medium.

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