An insulation-displacement terminal fitting and production method therefor

Abstract: [Object] To form insulation-displacement portions without thinly elongating side walls. [Solution] A wire W is connected by insulation displacement by being pushed in between insulation-displacement portions 17 projecting inwardly from a pair of side walls 12. The insulation-displacement portions 17 are formed to cantilever from the side walls 12 by making cuts in portions of the side walls 12 and bending cut portions inwardly, and bent portions 17A are formed by folding extending portions of the insulation-displacement portions 17 toward the side walls 12. Since the insulation-displacement portions 17 are formed to cantilever from the side walls 12, they are not thinly elongated unlike conventional insulation-displacement portions supported on side walls at their opposite ends.

Description: The present invention relates to an insulation-displacement terminal fitting and to a production method therefor. A known insulation-displacement terminal fitting is disclosed in Japanese Examined Patent Publication No. 57-10550. This terminal fitting is as follows. Insulation-displacement portions are formed in a pair of side walls to project inwardly substantially in V-shape, and a resin coating of a wire is cut open by the insulation-displacement portions, which are then brought into contact with a core of the wire at the cut-open sections of the resin coating by pushing the wire in between the insulation-displacement portions. In order to form the insulation-displacement portions in the side walls in the conventional insulation-displacement terminal fitting, a method has been adopted according to which portions of the side walls are bent in V-shape while being thinly elongated by a press. However, there is a limit in degree of elongation. Thus, there is a limit in narrowing a spacing between the insulation-displacement portions by increasing projecting distances of the insulation-displacement portions from the side walls. Further, an excessive elongation may result in a reduced strength. US 5934928, which discloses the features of the preambles of the independent claims, discloses a press-connecting terminal having press-connecting blades which are bent at a predetermined angle toward a contact portion side and are formed in the respective leading end portions of the press-connecting blades portions. In view of the above situation, an object of the present invention is to form insulation-displacement portions without thinly elongating side walls. This object is solved according to the invention by an insulation displacement terminal fitting according to claim 1 and by a production method according to claim 6. Preferred embodiments of the invention are subject of the dependent claims. According to a preferred embodiment of the invention, there is provided an insulation-displacement terminal fitting in which a resin coating of a wire is or can be cut open by bent portions at projecting ends of one or more insulation-displacement portions projecting inwardly from a pair of side walls and a core of the wire is or can be brought into contact with the bent portions of the insulation-displacement portions substantially at the cut-open sections of the resin coating by at least partly pushing the wire in between the insulation-dispfacement portions, wherein the insulation-displacement portions are formed to cantilever from the side walls by making cuts in portions of the side walls and bending the cut portions substantially inwardly, and the bent portions are formed by folding cantilever-shaped extending portions of the insulation-displacement portions toward the corresponding side walls. Since the insulation-displacement portions are formed to cantilever from the side walls, they are not thinly elongated unlike conventional insulation-displacement portions supported on side walls at their opposite ends. Furthermore, the one or more insulation-displacement portions extend from edges of openings left in the side walls by forming the insulation-displacement portions in directions away from the openings, and outward displacements of the insulation-displacement portions away from the wire are restricted by the contact of extending ends of the insulation-displacement portions with the inner surface of the side walls or with one or more stoppers formed on the side walls during connection with the wire by insulation displacement. Since the insulation-displacement portions will not be displaced in directions away from the wire, a specified contact pressure can be secured between the insulation-displacement portions and the wire. Preferably, the side walls are formed with one or more stoppers which are or can be engaged with the extending ends of the insulation-displacement portions for restricting movements or displacements of the extending ends substantially in parallel with the side walls which movements or displacements preferably are accompanied by deformations of the bent portions of the insulation-displacement portions to increase distances to the opposing side walls. If the insulation-displacement portions are deformed to increase distances to the opposing side walls while displacing their extending ends substantially in parallel with the side walls, projecting distances of the insulation-displacement portions from the side walls decrease. However, since the stopper(s) is/are formed to restrict the deformations of the insulation-displacement portions to increase the distances to the side walls and the displacement of the extending ends according to the present invention, the projecting distances of the insulation-displacement portions from the side walls are not reduced, with the result that a specified contact pressure can be secured between the insulation-displacement portions and the wire. Still further preferably, the stopper(s) are formed by embossing the corresponding side wall inwardly. Further preferably, the insulation-displacement portions may be formed in two positions of the side walls spaced apart in the longitudinal direction of the wire, such that the two insulation-displacement portions extend in opposite directions with respect to the longitudinal direction of the wire. Further preferably, wherein the at least one cut is formed substantially in the shape of H rotated by 90° and/or with at least one cut substantially in the shape of U rotated by 90°, the front and/or rear folded portions are preferably substantially symmetrically formed by this cut(s). Most preferably, wherein each folded portion is bent inwardly by about 90° to 150° and preferably to a side opposite from the other folded portion along a fold substantially at the front or rear end of the cut(s), and is further bent outwardly toward the side wall by about 90° to 150° along a fold substantially in the middle of the folded portion. According to the invention, there is further provided a method for producing an insulation-displacement terminal fitting in which one or more insulation-displacement portions projecting inwardly from a pair of side walls is or can cut open a resin coating of a wire and a core of the wire is or can be brought into contact with bent portions of the insulation-displacement portions substantially at the cut-open sections of the resin coating by at least partly pushing the wire in between the insulation-displacement portions, comprising the following steps: making cuts in portions of the side walls, bending the cut portions substantially inwardly to form the insulation-displacement portions to cantilever from the side walls, and folding cantilever-shaped extending portions of the insulation-displacement portions toward the corresponding side walls to form the bent portions, said method characterized in that the insulation-displacement portions are formed in directions away from the openings so that the one or more insulation-displacement portions extend from edges of openings left in the side walls, wherein outward displacements of the insulation-displacement portions away from the wire are restricted by the contact of extending ends of the insulation-displacement portions with the inner surface of the side walls or with one or more stoppers formed on the side walls during connection with the wire by insulation displacement. Preferably, wherein each side wall is formed with at least one slit substantially in the shape of H rotated by 90° and/or with at least one slit substantially in the shape of U rotated by 90°, the front and/or rear folded portions are preferably substantially symmetrically formed by this slit(s). Most preferably, wherein in the bending step each folded portion is bent inwardly by about 90° to 150° and preferably to a side opposite from the other folded portion along a fold substantially at the front or rear end of the slit, and is further bent outwardly toward the side wall by about 90° to 150° along a fold substantially in the middle of the folded portion. These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. FIG. 1 is a perspective view partly cut away of a first embodiment, FIG. 2 is a side view of the first embodiment, FIG. 3 is a plan view of the first embodiment, FIG. 4 is a partial enlarged horizontal section of the first embodiment, FIG. 5 is a partial development of the first embodiment, and FIG. 6 is a partial enlarged horizontal section of a second embodiment. Hereinafter, a first embodiment of the present invention is described with reference to FIGS. 1 to 5. An insulation-displacement terminal fitting T according to this embodiment is produced by applying, e.g. bending to a conductive metallic plate material stamped or cut out into a specified shape. The insulation-displacement terminal fitting T is substantially narrow in forward and backward or longitudinal directions as a whole, and a pair of side walls 12 extend upward from opposite side edges of a bottom wall 11 substantially over its entire length. An engaging portion 13 for the connection with a mating male terminal fitting (not shown) is formed at the front end of the terminal fitting T, a crimping portion 14 to be crimped or bent or folded into connection with a wire W is formed at the rear end of the terminal fitting T, and insulation-displacement portions 17 to be connected with the wire W by insulation displacement or cutting are formed in the middle. The engaging portion 13 is comprised of the front end of the bottom wall 11, the front ends of the side walls 12 and ceiling walls 15 which extend inwardly from the upper edges of the front ends of the side walls 12 while being preferably placed substantially one over the other, and is in the form of a substantially rectangular tube extending in forward and backward directions as a whole. The ceiling wall(s) 15 may be folded back onto itself, as shown in FIG. 1. The crimping portion 14 is comprised of the rear end of the bottom wall 11, and a pair of crimping pieces 16 formed at the rear end of the side walls 12. The pair of crimping pieces 16 are offset to each other with respect to or spaced along forward and backward directions, and are or can be crimped or bent or folded into connection with the wire W supplied or at least partly inserted between the side walls 12 while being arcuately deformed. It should be noted that this crimping step is performed preferably simultaneously with or before or after a step of insulation displacement to be described later. Next, the insulation-displacement portions 17 are described. The insulation-displacement portions 17 are preferably provided substantially in the middle of the insulation-displacement terminal fitting T with respect to forward and backward directions and preferably in two positions spaced apart or offset in forward and backward directions in each of the side walls 12, i.e. preferably a total of four insulation-displacement portions 17 are provided. Two insulation-displacement portions 17 transversely arranged to hold the wire W are paired, i.e. two front and rear pairs of the insulation-displacement portions 17 are formed in one insulation-displacement terminal fitting T. In a development of the terminal fitting T before bending and embossing are applied, each side wall 12 is formed with a slit 18 substantially in the shape of H rotated by 90° (FIG. 5). In case only two insulation displacement portions 17 are to be provided (i.e. one on each side wall 12) the slit may have substantially a U-shape rotated by 90° (not shown). Two front and rear folded portions 19 are substantially symmetrically formed by this slit 18. Each folded portion 19 is bent inwardly by about 90° to 150° and to a side opposite from the other folded portion 19 (forward in the case of the front folded portion 19 and backward in the case of the rear folded portion 19) along a fold 20 at the front or rear end of the slit 18, and is further bent outwardly (toward the side wall 12) by about 90° to 150° along a fold 21 substantially in the middle of the folded portion 19. The insulation-displacement portion 17 is formed by this bending substantially projecting inwardly from the side walls 12. The insulation-displacement portion 17 thus formed by making a cut in a portion of the side wall 12 and bending a cut portion inwardly cantilevers from the side wall 12, and is folded back toward the side wall 12 at the fold 21, so that it has a triangular section when viewed from above. This triangularly or pointedly bent portion serves as a bent portion 17A. The insulation-displacement portion 17 extends from an opening edge 23 of an opening 22 left in the side wall 12 by forming the insulation-displacement portion 17 in a direction away from the opening 22, and an extending or distal end 17B thereof is oblique to and spaced from the inner surface of the side wall 12. The side walls 12 are formed with stoppers 24 for engaging the extending ends 17B of the insulation-displacement portions 17 by being embossed to project inwardly. The stoppers 24 are individually provided for the respective insulation-displacement portions 17, and engage the forward extending ends 17B of the front insulation-displacement portions 17 from front while engaging the backward extending ends 17B of the rear insulation-displacement portions 17 from behind. This prevents the forward and backward displacements of the extending ends 17B accompanied by the deformations of the bent portions 17A of the insulation-displacement portions 17 to increase distances to the opposing side walls 12. Each pair of the transversely arranged insulation-displacement portions 17 are symmetrical with each other, and the two insulation-displacement portions 17 formed in positions of the same side wall 12 displaced in forward and backward directions are also symmetrical with each other. A spacing between the bent portions 17A of the pairs of the transversely arranged insulation-displacement portions (minimum spacing between the insulation-displacement portions 17) is set slightly smaller than the outer diameter of a core Wb of the wire W. Next, the action of this embodiment is described. The wire W having its longitudinal axis oriented substantially in forward and backward directions (substantially parallel to the longitudinal direction of the terminal fitting T and the side walls 12) is at least partly pushed in between the side walls 12 of the insulation-displacement terminal fitting T according to this embodiment in a direction at an angle different from 0° or 180°, preferably substantially normal to the longitudinal axis thereof. As the wire W is pushed in, the bent portions 17A cut the resin coating Wa of the wire W open between the respective pairs of the transversely arranged insulation-displacement portions 17 and bite in the cut-open sections of the resin coating Wa to be brought into contact with the core Wb. Since the insulation-displacement portions 17 are formed so that their free ends extend from the side walls in this embodiment, there are advantages that the insulation-displacement portions 17 are thicker than those formed by bending portions of the side walls to project inwardly while thinly elongating them and that preferably plating at the outer surfaces of the insulation-displacement portions 17 is free from cracking and peeling. Further, in the case that the side walls 12 are thinly elongated to form the insulation-displacement portions 17, the insulation-displacement portions 17 are thinner as the projecting distance thereof from the side walls 12 are longer. However, in this embodiment, the insulation-displacement portions 17 do not become thinner regardless of how the projecting distances of the insulation-displacement portions 17 from the side walls 12 are set. Thus, the projecting distances of the insulation-displacement portions 17 from the side walls 12, i.e. distances between the insulation-displacement portions 17 can be arbitrarily set. If the insulation-displacement portions 17 are deformed to increase distances to the opposing side walls 12 while displacing their extending ends forward or backward in parallel with the side walls 12, the projecting distances of the insulation-displacement portions 17 from the side walls 12 decrease, which may cause a reduction in contact pressure with the wire W. However, since the stoppers 24 are formed in the side walls 12 to restrict the deformation of the insulation-displacement portions 17 to increase the distances to the opposing side walls 12 and the displacements of the extending ends 17B in this embodiment, the projecting distances of the insulation-displacement portions 17 from the side walls 12 are not reduced, with the result that a specified contact pressure can be secured between the insulation-displacement portions 17 and the wire W. Next, a second embodiment of the present invention is described with reference to FIG. 6. The second embodiment differs from the first embodiment in the positional relationship between the extending ends 17B of the insulation-displacement portions 17 and the side walls 12. Since the other construction is same or similar as in the first embodiment, no description is given on the structure, action and effects thereof by identifying it by the same reference numerals. Unlike the first embodiment in which the extending ends 17B of the insulation-displacement portions 17 are spaced away from the side walls 12, the extending ends 17B of the insulation-displacement portions 17 are obliquely in contact with the inner surfaces of the side walls 12 or edges of the extending end 17B come into contact with the inner side of the side walls 12 in the second embodiment. This eliminates a possibility of displacements of the bent portions 17A of the insulation-displacement portions 17 in directions away from the wire W (directions toward the side walls 12), thereby securing a specified contact pressure between the insulation-displacement portions 17 and the core Wb of the wire W. Further, the stoppers 24 engaged with the extending ends 17B of the insulation-displacement portions 17 restrict the sliding movements preferably along the longitudinal direction of the terminal fitting T of the extending ends 17B on the side walls 12 accompanied by deformations of the bent portions 17B of the insulation-displacement portions 17 to increase the distances to the opposing side walls 12. The present invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined in the claims. Beside the following embodiments, various changes can be made without departing the present invention as defined in the claims. Although two pairs of front and rear insulation-displacement portions are provided in the foregoing embodiment, one, three or more pairs of insulation-displacement portions may be provided according to the present invention. LIST OF REFERENCE NUMERALS T insulation-displacement terminal fitting W wire Wa resin coating Wb core 12 side wall 17 insulation-displacement portion 17A bent portion 17B extending end of the insulation-displacement portion 22 opening 23 opening edge 24 stopper

Claims: An insulation-displacement terminal fitting (T) in which a resin coating (Wa) of a wire (W) can be cut open by bent portions (17A) at projecting ends of one or more insulation-displacement portions (17) projecting inwardly from a pair of side walls (12) and a core (Wb) of the wire (W) can be brought into contact with the bent portions (17A) of the insulation-displacement portions (17) substantially at the cut-open sections of the resin coating (Wa) by at least partly pushing the wire (W) in between the insulation-displacement portions (17), wherein the insulation-displacement portions (17) are formed to cantilever from the side walls (12) by making cuts (18) in portions of the side walls (12) and bending the cut portions (19) substantially inwardly, and the bent portions (17A) are formed by folding cantilever-shaped extending portions (17B) of the insulation-displacement portions (17) toward the corresponding side walls (12), characterized in that the one or more insulation-displacement portions (17) extend from edges (23) of openings (22) left in the side walls (12) by forming the insulation-displacement portions (17) in directions away from the openings (22), and outward displacements of the insulation-displacement portions (17) away from the wire (W) are restricted by the contact of extending ends (17B) of the insulation-displacement portions (17) with the inner surface of the side walls (12) or with one or more stoppers (24) formed on the side walls (12) during connection with the wire (W) by insulation displacement. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the one or more stoppers (24) are or can be engaged with the extending ends (17B) of the insulation-displacement portions (17) for restricting movements of the extending ends (17B) substantially in parallel with the side walls (12). An insulation-displacement terminal fitting according to claim 2, wherein the stopper(s) (24) are formed by embossing the corresponding side wall (12) inwardly. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the at least one cut (18) is formed substantially in the shape of H rotated by 90° (FIG. 5) and/or with at least one cut substantially in the shape of U rotated by 90°, the front and/or rear folded portions are preferably substantially symmetrically formed by this cut(s) (18). An insulation-displacement terminal fitting according to claim 4, wherein each folded portion (19) is bent inwardly by about 90° to 150° and preferably to a side opposite from the other folded portion (19) along a fold (20) substantially at the front or rear end of the cut(s) (18), and is further bent outwardly toward the side wall (12) by about 90° to 150° along a fold (21) substantially in the middle of the folded portion (19). A method for producing an insulation-displacement terminal fitting (T) in which one or more insulation-displacement portions (17) projecting inwardly from a pair of side walls (12) can cut open a resin coating (Wa) of a wire (W) and a core (Wb) of the wire (W) can be brought into contact with bent portions (17A) of the insulation-displacement portions (17) substantially at the cut-open sections of the resin coating (Wa) by at least partly pushing the wire (W) in between the insulation-displacement portions (17), comprising the following steps: making cuts (18) in portions of the side walls (12), bending the cut portions (19) substantially inwardly to form the insulation-displacement portions (17) to cantilever from the side walls (12), and folding cantilever-shaped extending portions (17B) of the insulation-displacement portions (17) toward the corresponding side walls (12) to form the bent portions (17A), said method characterized in that the insulation-displacement portions (17) are formed in directions away from the openings (22) so that the one or more insulation-displacement portions (17) extend from edges (23) of openings (22) left in the side walls (12), wherein outward displacements of the insulation-displacement portions (17) away from the wire (W) are restricted by the contact of extending ends (17B) of the insulation-displacement portions (17) with the inner surface of the side walls (12) or with one or more stoppers (24) formed on the side walls (12) during connection with the wire (W) by insulation displacement. A method according to claim 6, wherein each side wall (12) is formed with at least one slit (18) substantially in the shape of H rotated by 90° (FIG. 5) and/or with at least one slit substantially in the shape of U rotated by 90°, the front and/or rear folded portions are preferably substantially symmetrically formed by this slit(s) (18). A method according to claim 7, wherein in the bending step each folded portion (19) is bent inwardly by about 90° to 150° and preferably to a side opposite from the other folded portion (19) along a fold (20) substantially at the front or rear end of the slit (18), and is further bent outwardly toward the side wall (12) by about 90° to 150° along a fold (21) substantially in the middle of the folded portion (19).

Inventors: HIO MASAHIDE, KOJIMA EIJI, HIO, MASAHIDE, KOJIMA, EIJI
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2001
Main classification: H01R4
IPC codes: H01R4, H01R43