Electric cable stripping method and electrical cable loosening device

Abstract: An electrical cable loosing device (SD) for loosing an electric cable (P) having a conductor wire (3) covered by an insulating material (4 and 5) has a clamping unit (11), a stop unit (14), and pounding unit (12 and 13). The clamping unit (11) clamps the electrical cable (P). The pounding unit (12 and 13) pounds and bends the cable end portion (Pe) against the stop unit (14). Thus, the insulating material (4 and 5) separates from the conductor wire (3) at the end portion (Pe) to facilitate the stripping of the insulating material (4 and 5).

Description: The present invention relates to a stripping method for automotive resistance cable and other similar type of electrical cables, and to an electrical cable loosening device used for said stripping operation. As shown in Fig. 2, a shielded cable P for use in automobiles has a tension member 1 made of an aramid or other polymer fiber, a core 2 formed around the tension member 1, a resistance wire 3 as a conductor wound in a spiral pattern around the core 2, an insulator 4 provided around the resistance wire 3, and a sheath 5 provided around the insulator 4. In Fig. 3, the cable stripping operation of the cable P is schematically shown. To strip the end of the cable P, the sheath 5 and the insulator 4 are cut to have a cross section of circles by a stripping knife A, after which the stripping knife A is moved in the direction of the arrow to pull off the sheath 5 and the insulator 4 (forming the stripped part B indicated in imaginary lines). In such a cable P as shown in Fig. 2, since the resistance wire 3 is spirally wound around the core 2, the inner surface of insulator 4 is thus interposed between the ridges of the spirally wound resistance wire 3. As a result, when the cable P is stripped of the insulator 4 and sheath 5, the insulator 4 is forced to move over and across the ridges of resistance wire 3. However, when the insulator 4 does not move or slide smoothly, the resistance wire 3 may be unwound or unravelled as shown in Fig. 4, or may be broken as shown in Fig. 5 resulting in scraping of the surface of core 2. This is specifically caused by the tight engagement between the conductor 3 and the insulator 4, and equivalent damage may also occurs when stripping other similar type of electrical cables. US-A-3 780 928 discloses an apparatus for stripping brittle wire insulation by means of a pair of opposing hard, smooth glass blocks diametrically pressed against the coating. These reciprocally moving glass blocks fracture the coating of the insulated wire without bending the end portion of the wire. Therefore, this known, this apparatus and method are applicable only in case of hard and brittle wire insulation. FR-A-2 502 858 discloses an apparatus for stripping flat cables; said apparatus comprises a guiding means comprised of a fixed guide and a clamping means having a hammer operated by a thruster in order to position and clamp the cable on the fixed guide (see e.g. page 2, lines 18-20). This hammer does not pound the insulation of the cable since the flexible insulation of the flat cable is cut by means of the cooperating knifes. The present invention has been developed with a view to substantially solving the above described disadvantages and has for its essential object to provide an improved electrical cable stripping method and an improved electrical cable loosening device. This object is solved with the features of the claims. These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings throughout which like parts are designated by like reference numerals, and in which: Fig. 1 is a schematic side view of an electrical cable loosening device according to a preferred embodiment of the invention, Fig. 2 is a cut-away view of part of a wrapped cable, and Figs. 3, 4, and 5 are schematic views for illustrating the stripping operation of the coating member at the cable end portion. Referring to Fig. 1, an electrical cable loosening device SD according to a preferred embodiment of the present invention is shown in which an electrical cable P is inserted. The stripping device SD has a generally C-shaped frame F including a horizontal base 15 and a generally inverted-L-shaped vertical stand, a clamp unit 11 provided at the front end of the vertical stand of frame F for clamping the cable P, a stop unit 14 provided on a lower surface of the vertical stand of Frame F, a cylinder unit 13 provided on a horizontal base of frame F adjacent the vertical stand of frame F, and a pressure unit (dog) 12 connected to the cylinder 13 for making reciprocating movement to press the inserted cable P against the stop unit 14, repeatedly. In the frame F, the lower surface 14 of the vertical stand is facing and substantially parallel to the surface of the horizontal base 15. In operation, cable P which is held by clamp 11 is brought to a pounding station at which the end portion Pe of cable P is located between the stop unit 14 and pressure unit 12. At the pounding station, the pressure unit 12 reciprocates by the cylinder 13 between the positions indicated by a solid line and a dot-dash line, as shown in Fig. 1, to pound and bend the cable end portion Pe. Thus, the insulator 4 separates from the resistance wire 3, so that the resistance wire 3 is loosened. The number of striking the cable end Pe is empirically determined. Thus, at a stripping station which is next to the pounding station, the insulation coating such as the insulator 4 and sheath 5 can be removed smoothly. A detail of the stripping station, as well as the clamping arrangement, is disclosed in later EP-A-487969. According to the present invention, since the cable is stripped after loosening the end portion thereof as thus described, the unravelling and the damage to conductor and core can be reduced. Thus, the yield of stripped cable is improved.

Claims: A stripping method for stripping an electrical cable (P) having a conductor wire (3) wound around a core member (2) and a coating member (4 and 5) tightly mounted on said conductor wire (3), said method comprising the steps-of: clamping said electrical cable (P) at a clamping position which is adjacent an end portion (Pe) of said electrical cable (P); pounding and bending said end portion (Pe) to separate said coating member (4 and 5) from said conductor wire (3); and stripping said electrical cable (P) of said coating member (4 and 5) at the pounded end portion (Pe). An electrical cable loosing device (SD) for loosing an electric cable (P) having a conductor wire (3) wound around a core member (2) and a coating member (4 and 5) tightly mounted on said conductor wire (3), said device comprising: a frame structure (F); a stop surface (14) formed on said frame structure (F); a clamping means (11) for clamping said electrical cable (P) at a clamping position which is adjacent an end portion (Pe) thereof; a pounding means (12 and 13) provided on said frame structure (F) and in association with said stop means (14), for pounding and bending end portion (Pe) against said stop surface (14).

Inventors: HASHIMOTO NORIHIKO, ISHIKAWA SUMINORI, HASHIMOTO, NORIHIKO, ISHIKAWA, SUMINORI
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1991
Main classification: H02G1
IPC codes: H01R43, H02G1