DE2009110A1 - Stripping of wires - Google Patents

Description

Dr. Ing. H. Kf; ^ ..-: i _{<: i} : ii

Dipl.Jng.-H. HsiKk-

Dip '. Phyii W. Schmüz

Td. 538ÖS & 6

Burroughs Corporation -

607.I Second Avenue ■ February 24, 1970

Detroit, me. 48232, U.S. Attorney File M-1O54

Stripping of wires

The invention relates to a method for stripping conductor wires using pure heat ^N radiate. A clamping device and mask arranged between two heat radiation sources expose only that part of the insulation to the radiation that is to be removed. Some of the insulation adjacent to the exposed wire is cut off and pushed over the previously exposed wire. This means that the wire that is now exposed is free of contamination and was also not exposed to heat deformation.

The invention is particularly advantageous in machines where large series of electrical cables with many conductors are used, and where these wires are at points of their running length and at should be connected to their endpoints, such as when wiring the back of the printed circuit boards of calculating machines. The rear wiring is used to connect various printed circuits and to connect the components

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box elements that are becoming increasingly important in computers. Computers require a large number of isolated cooels, usually on flat cables that run at right angles around corners, posts and carriers can be routed around and which can be grouped into cable harnesses for easier handling. Again Name says, the term flat cable applies to a group of wires that are arranged in a plane and usually individually are isolated. A well-known example of a two-core flat cable is the cable that connects a television antenna to the television. The flat cable is to be distinguished from the coaxial cable, wherein the wire strands are generally arranged in a circular cross-section. The individually isolated The wires of a flat cable can be solid wires or stranded wires.

As a result of the high speed of operation of modern computers, a high level of electrical insulation is required in order to Effectively eliminate stray voltages. Teflon insulation fulfilled this task extraordinarily pitiful. Teflon is the trade name of DiPoio for the Kchl'inEtofi'lic.rz-Dünnscrii, h /, T - :; rafluoroethylene. Teflon TFS refers to the high molecular weight homopolymer of tetrafluoroethylene from DuPontj's corresponding process for the production of Teflon TFE are described in US Pat. Nos. 2,476,222) and 2,559,752. Designated Teflon FEP the high molecular weight copolymer of Teflon TFE (tetrafluoroethylene) from DuPont and HFP (hexafluoropropylene) with a ratio of TFE to HFP of about 90: 1 o to about 50:50, and preferably about 85:15. The corresponding Methods for making Teflon FEP are described in U.S. Patent 2,946,763. These Teflon thin films or films

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may contain color pigments, fillers, and other film-forming polymers as described in US Pat. No. 2,820,752. Kapton or Polykapton are DuPont's trade names for polyimide films; such polyimide films are described in US Pat. No. 3,117y6) 4. In the context of the invention, therefore, the terms "poly-insulation" and other types of insulation with the prefix "poly" are used to denote insulation made of one or more of the following materials: Teflon, Teflon TFE, Teflon FEP, Kapton and other polymers, copolymers, vinyls, vinyl chlorides, polyimides A and other materials with high insulating properties, and should be interpreted as such, except in cases where ambiguity may arise. The difficulties that arise when stripping pcly-insulated wire result from the low-friction smoothness, as well as the splitting and tear resistance, which are peculiar to these materials.

Procedure for stripping conductor wires (single and Multiple strands) are known, but have in Pcly insulation, ^ in contrast to the method according to the invention, has not yet led to satisfactory results.

The known mechanical method uses stripping devices. These may work perfectly for stripping wire ends, However, they are not suitable for stripping a section of poly-insulation along the length of the wire. Will the Poly insulation cut and stripped from the wire so it splits because of their high elasticity, they do not detach, and. at the. .-.

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Removing the stripping tool moves the poly insulation in return to their original position. In addition, if the cable made fine If there is stranded wire, the strands can be notched or cut due to the large tolerances of the stripping knife. These notches form weak points at which the strands can easily break and thus different resistance values at different ones Can produce parts of the cable.

Another method is to burn off the insulation. This is achieved with an electric heating wire or a flame. The previous burn-off methods are unsatisfactory because they leave an oxide layer on the wire and not have any clean edges leave the remaining insulation. In addition, this Aborennverfahren cannot easily be applied to a single wire in one Restrict flat cables. Finally, burning (oxidation by the application of heat) gave unsatisfactory results because the electrical heating wire only has a short service life at the high temperatures (1093 to 1371 ° C) required for Removal of poly insulation are required. An example of the Firing process at temperatures in the range of 843 ° C is described in US Pat. No. 3,374,117 dated March 19, 1968.

Another method from the prior art uses coherent light (laser): this method is also unsatisfactory because the laser beam is so small (few , and diameter) that it has to be deflected and guided over the entire area to be stripped. In addition, the laser beam penetrates

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: d. through the insulation and damaging the conductor. In addition, the applicant is not aware of any device for the successful stripping of insulation on both sides of a conductor wire using laser beams.

A state-of-the-art technology and based on the The method that establishes the chemical properties of the insulation consists in etching the insulation by acid treatment. Poly insulation however, are highly acid-resistant, and the acid method remains unsatisfactory. ■,

Accordingly, the object of the invention is to provide a new and improved method and apparatus for removing poly-insulation to be provided by a leader.

The invention also provides a new and improved method and device created that is particularly suitable for stripping flat cables. Next with the invention a new and improved method and device for optional stripping individual insulated conductors of a flat cable are offered. The invention also provides a new method and device created to remove poly insulation from a conductor, the exposed conductor remains free of contamination, in order to obtain good electrical conductivity or low transition resistances.

These and other advantages of the invention are achieved in that the part to be stripped is provided with poly-insulation

Solid wire or stranded conductor of pure thermal energy or pure

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Thermal radiation, especially infrared or ultraviolet radiation exposed to high temperatures for a short period of time is used to evaporate the poly-Isclierung or otherwise to decompose.

The poly-insulations described above evaporate under pure Thermal radiation without leaving deposits on the conductors; this creates the prerequisite for excellent electrical contact.

Poly insulation is produced in both colored and transparent forms. It may be that the color pigments of the fare Insulation does not completely decompose under B radiation and leave impurities on the wire surface, even when the irradiation is carried out in an inert gas atmosphere is carried out. If necessary, this contamination can be removed with ultrasound.

After the irradiation, an adjacent section of polyisolation is made separated and slid over the previously exposed wire to expose new portions of the wire. These new exposed Wire sections were not directly exposed to the pure thermal radiation and are therefore not thermally deformed. Also own the newly exposed wires had a uniform density because they were not subjected to the tension of the jig. The device according to the invention contains two radiation sources, between which a workpiece clamp is arranged.

BAD ORfOINAL

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The workpiece clamp or the clamping device-is with a apertured shield or mask used only to expose the parts to be stripped to radiation.

Will be a transparent or neutral colored poly-insulation used, it can be coated with a heat-absorbing paint, E.g. black, brown or red can be coated in order to increase the speed of the heat absorption of the insulation.

These and other features of the invention are illustrated by means of exemplary embodiments explained in more detail in connection with the drawings. In the drawings, the same reference numerals are used The same parts in each case. Show it:

Fig. 1 'is a perspective view of part of a flat cable;

Fig. 2 is a schematic representation of the device for removing the poly insulation through pure thermal energy;

3V consisting of FIGS. 3a and 3b is a front view of two shields provided with openings or masks; . .

4 shows a perspective view of the part of a flaoh cable, from which part of the insulation has been removed ;;

5 is a perspective view showing an adjacent Section of insulation on the spot

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is pushed, which was previously stripped by thermal energy.

1 shows a flat cable 11 with a row of conductors 13 (which can consist of VoILwire or stranded wires). Each conductor 13 is embedded in a poly insulation 15. With this flat cable eight wires are shown as an example. It will be understood that the number of wires depends on the application requirements as well as from depends on the size and handling of the cable.

2 shows a schematic representation of the device according to the invention for removing the poly insulation. The heat sources or generators 17 and 19 are cylindrical, strand-shaped reflectors, at the focal points of which there is, for example, a source of infrared or ultraviolet radiation, which are horizontally opposite one another. Generators of this type are commercially available, for example from Spectra Corporation, Trenton, New Jersey. These generators deliver "pure thermal energy"; this means radiation that is free of electrons and flames. Between the generators 17 and 19 a jig 21 is arranged, in which the Kaoel se is clamped, that the wires 13 assume a vertical position.

The Einspannvcrriehtang 21, which serves both as a workpiece clamp and as a heat dissipation, has an opening 23 and on each Side a mask 25 each with an opening 29. For the purpose of explanation the masks in the drawing are shown separately from the clamping device 21, but in practice the

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Masks and the jig in contact with each other. That The device of Fig. 2 is shown in a horizontal plane. However, it is obvious that the device and the cable are rotated 90 ° can be so that the generators 17 and 19 are perpendicular to each other. A fan (not shown) on the generators ensures that the vapors are extracted when the insulation chemically breaks down and evaporates. The jig 21 and the masks 25 are shown as three separate units, but it will be understood that there is only one mask 25 on the opposite side of the cable the clamping device 21 would be required if the clamping device 21 is provided with the corresponding openings 25.

FIG. 3a shows a front view of the mask 25 of FIG. 2 with the opening 29 and the surface 39 made of a radiation-reflecting Material such as aluminum. Using this mask 25 leads to the removal of the insulation 15 from all wires 13, as shown in Fig. 4, for example. In Fig. 3b is another mask 27 with a number of openings 31 is shown. If the mask 27 is used, the insulation 15 can optionally be removed, i.e. the insulation need not be of all of the I3 wires from the same Surface are evaporated along their length. It However, care must be taken that the openings of the two masks align with each other so that the insulation from the front and back Back of the same wire section is removed.

4 shows a perspective view of a flat cable 11, a part of the insulation 15 has been removed. The stripped

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AO

Surface 33 is the length "L" over which the wires 13 are exposed. This shows the effect of the heating process, which evaporates or decomposes the insulation. The infrared radiation for example, left oei for a period of about 5 to 10 seconds Temperatures between about 1100 and about 14OO ° C act. While During the heating process, air pollution often occurs as a result of the vapors that evaporate or decompose Isolation occur. A fume cupboard with an exhaust fan (not shown) should be used here for the elimination of these fumes as the fumes from the pcly insulation can be toxic Vapors can just as easily be blown out of the work area with compressed air.

After the poly insulation evaporates in the thermal energy process a cut is made at the front and back of the insulation along path 35, either mechanically or by pure thermal energy made. Since Nautr's poly insulation is smooth and low-friction, an abrasive material, such as carborundum, is Sandpaper, grained steel, or the mechanical cutting tool itself used to remove some of the insulation 37 to push on the area 33, from which previously the insulation had been removed.

The ^{length 11} L "of the insulation 37 to be displaced is equal to or greater than the length of the insulation 33 that has been removed. As a result, a new section of the flat cable 11 is exposed for the most varied of connections. This new section of the flat cable

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was not exposed to possible thermal deformation and thus retains its maximum electrical contact properties. Since the conductors I3 are very small, the parallel spacing between the conductors can be impaired during heating and when clamping in the clamping device. Such changes in the parallel spacing are compensated for when the insulation 'yj is pushed over the previously exposed wire mesh sections.

If the poly insulation does not evaporate completely, residues, such as pigments from the colored insulation, can remain on the conductors. Therefore, another step may be required before cutting off and pushing on the adjacent poly insulation. This step, if necessary, consists of ultrasonic cleaning of the wires in order to remove the residues. In the case of insulation made of polyimides, these residues can also be washed off with alcohol.

In an optionally applicable process with coloring of the poly-insulation, the dye, 2.B- a coloring paste, is not evaporated like the poly-oil oil, but leaves behind a color in a normal atmosphere ^; In order to use this method, we recommend using an inert gas atmosphere such as nitrogen. läätüilich ICANN leash IiTertgasätmi ph ^ ^ e "in all other cases ^r iiferwetidet weräeti, χϊήά äaljel'd" elhd oxidation irgeriawelcher partially decomposed components of the Poly-isolation can be prevented.

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In addition, the use of additional shielding between the radiation sources 17 and 19 and the cable 11 may be required to shield the cable until the sources have reached their operating temperature, which for example in the case of infrared can take another ten seconds. Also the mask decoration can be a feature of the radiation source, i.e. it can be built into it, and at the source, for example, a . Membrane can be provided in the desired shape. Likewise, the source can also be optical systems with lenses and reflectors own to shape and direct the thermal radiation.

In connection with the stripping, the invention became an x-ply insulation described by a flat cable or wire bundle, but it is obvious that the method for Abiscelling visler other types of insulation can be used without departing from the scope of the invention.

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Claims (1)

Claims Method of stripping insulation from electrical Conductors of a cable, characterized by a controllable Irradiating the cable to vaporize or decompose the insulation. 2. The method according to claim 1, characterized / that the electrical insulation made of at least one of the substances of the • the following group consists of: tetrafluoroethylene, hexafluoropropylene, Polyimides and polyvinylchloride (PVC). 3. The method according to claim 1 or 2, characterized in that the electrical insulation consists of tetrafluoroethylene. 4. The method according to any one of the preceding claims, characterized in that the electrical insulation consists of a mixture of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), the ratio of PFE and HFP being in the range from 90:10 to 50:50 . . ■ ■ ■ ' - 1 . 009838/1517 5 · Method according to one of the preceding claims, characterized through additional preparation of the conductors in order to give the conductor surfaces a low contact resistance. Ö.Verfahren according to any one of the preceding claims, characterized in that the controllable irradiation is an optional
Includes shielding of 'ropes of the cable. 7. The method according to claim 5 or 6, characterized in that ultrasound cleaning of the exposed
Head heard. 8.Verfahren according to any one of claims 5, 6 or 7, characterized in that the processing also includes the following operations
includes: Cutting off the insulation adjacent to the exposed conductors and Slide the cut insulation onto the exposed conductors. 9. The method according to claim 5, characterized in that the irradiation acts for a period of 5 to 10 seconds in a temperature range of about 1100 to about 1400 ° C. 10. The method according to any one of the preceding claims, characterized in, that the irradiation is carried out by ultraviolet radiation. & 0-9838 / 1517 11. The method according to any one of the preceding claims, characterized in that that the irradiation is carried out by infrared radiation. , - 12. The method according to any one of the preceding claims, characterized in, that the irradiation is carried out in an inactive gas. 13. The method according to any one of the preceding claims, characterized by the further process of clamping the cable in - ^ a workpiece clamp. ; 14. The method according to claim 13, characterized in that the Clamping involves the following process: shielding certain conductors with an apertured one Umbrella. 15. The method according to claim 13 or 14, characterized in that that the restraint comprises the following process: Optionally shielding parts of the cable from the ^ j Radiation. 16. The method according to any one of claims 13, 14 or 15, characterized characterized in that the irradiation in an inactive gas he follows. .. "-" ..- IT. Method according to one of the preceding claims, characterized through the further process of processing the irradiated cable. 0Π QQ "3 Q / 1 CiT '
U 9 0 J ο / I3l / BATH ORIGINAL 18. The method according to claim 17 * characterized in that the Reconditioning includes the following process: The ultrasonic cleaning of the exposed conductors to make contact surfaces with low electrical contact resistance. 19. The method according to claim 17 or l8, characterized in that the processing comprises the following operations: Separation of the insulation adjacent to the exposed conductor Slipping the severed insulation onto the irradiated exposed conductors. - 4 -009838/1517