A terminal fitting and a production method

Abstract: [Object] To provide a cramping terminal fitting which can maintain a satisfactory contact state with a wire without applying plating again after being shaped by a press. [Solution] Insulation displacement contact (IDC) portions 6 into which a wire can be pushed are provided in the middle of a cramping terminal fitting 1. Each IDC portion 6 is comprised of a contact portion 9 formed by embossing side walls 5 in such a manner as to have a triangular cross section, and cutting blades 8 formed by bending long pieces 18 and short pieces 17 to have a triangular cross section. Further, guide portions 10 for guiding the wire to the IDC portions 6 are provided above the cutting blades 8. Since the contact portions 9 remain plated, a contact state with the wire can be satisfactorily maintained.

Description: The present invention relates to a terminal fitting (cramping terminal fitting or insulation displacement fitting) and to a production method therefor. FIGS. 11 and 12 show a cramping terminal fitting 100 disclosed in Japanese Unexamined Patent Publication 6-333613. Insulation displacement contact (IDC) portions 101 for making cuts in an insulation coating of an unillustrated insulated wire are provided in the middle of this cramping terminal fitting 100. Each IDC portion 101 is substantially U-shaped opening upward as shown in FIG. 12. Cutting blades 102 for cutting the insulation coating of the wire are provided at the opening edge of the IDC portion 101, whereas a contact portion 103 to be brought into contact with a core of the wire is provided below the cutting blades 102. An electrically conductive plate member used as a material for the cramping terminal fitting is plated before being pressed for an anticorrosion purpose. Thus, plating at cut ends comes off in the prior art cramping terminal fitting 100, second plating needs to be applied after being shaped by a press in order to maintain a satisfactory contact state between the contact portion 103 and the wire since the cutting blades 102 and the contact portion 103 are formed on the cut ends. Moreover, EP 0 352 966 B1 discloses an electrical connection member having a channel into which a wire can be inserted and in which insulation severing edge surfaces converging towards each other and coming into contact with the wire inserted into the channel thereby displacing its insulation coating. By further inserting the wire into the channel, crests of bowed portions formed by arcuate dimples in the walls of the channel enter the incisions made by the insulation severing edge surfaces thereby contacting the core of the wire. However, the core of the wire may be improperly contacted by the bowed portions e.g. when the wire is not completely properly oriented. FR 2 388 421 discloses an electrical connector having an insulation-opening contact member, wherein the protruberances on each side wall are aligned to form conductor-receiving notches adapted to penetrate the insulation of the wire and establish electrical connection with a conductor. EP 0722 197 discloses an electrical connector assembly comprising an electrical terminal seated within a housing, wherein the terminal includes an insulation displacement contact section adapted for receiving a multitude of through wire diameters along the length thereof and a conductor engaging section for electrical engagement with a mating wire end where said assembly has a first position with the terminal in the housing and the IDC section is open for engaging the wire along the length thereof. The present invention was developed in view of the above problem, and an object thereof is to provide a terminal fitting which comprises an improved cutting blade, which can maintain a satisfactory contact state in particular with a wire without applying plating again after being shaped by a press. This object is solved according to the invention by a terminal fitting according to claim 1 and by a method according to claim 7. Preferred embodiments of the invention are subject of the dependent claims. According to the invention, there is provided a (cramping or insulation displacement) terminal fitting which has at least one insulation displacement contact portion electrically connectable with a core of an insulated wire by making cuts in an insulation coating as the insulated wire is pushed into the insulation displacement contact portion, wherein the insulation displacement contact portion is formed by embossing one side wall or more substantially opposing side walls of the terminal fitting inward such that embossed portions substantially have a triangular cross section, and being capable of tightly holding the core between the opposing ridges of the embossed portions, wherein the insulation displacement contact portion comprises one or more cutting blades for making cuts in the insulation coating of the insulated wire and one or more contact portion which is provided below or behind the cutting blades as seen in an insertion direction of the insulated wire to be brought into contact with the core, said terminal fitting characterized in that at least one guide portion for guiding the wire to the insulation displacement contact portion is provided above the insulation displacement contact portion, wherein the guide portion has an inclined portion having an inclination angle being substantially the same as an inclination angle of an inclined portion of the cutting blades. According to a preferred embodiment of the invention, the contact portion is formed by embossing opposing side walls of the terminal fitting inward. Most preferably, the terminal fitting is formed by bending an electrically conductive plate member preferably having its front surface plated. According to a further preferred embodiment of the invention, there is provided a terminal fitting which is formed by bending an electrically conductive plate member having its front surface plated and has an insulation displacement contact portion electrically connectable with a core of an insulated wire by making cuts in an insulation coating as the insulated wire is pushed into the insulation displacement contact portion, wherein the insulation displacement contact portion comprises cutting blades for making cuts in the insulation coating of the insulated wire and a contact portion which is provided below the cutting blades to be brought into contact with the core, the contact portion being formed by embossing opposing side walls of the terminal fitting inward such that embossed portions have a triangular cross section, and being capable of tightly holding the core between the opposing ridges of the embossed portions. Accordingly, by pushing the insulated wire into the insulation displacement contact portion, the cutting blades cut the insulation coating and the contact portion provided therebelow is brought into contact with the core. Since the contact portion is formed by embossing the side walls of the terminal fitting inward, a satisfactory contact state can be maintained without peeling the plating on the front surface. Furthermore, at least one guide portion for guiding the wire to the insulation displacement contact portion is provided above the insulation displacement contact portion. Further preferably, a guide portion for guiding the wire to the cutting blades is provided above the cutting blades. Accordingly, the insulation coating of the wire is smoothly cut since the wire is guided to the cutting blades by the guide portion. Further, the guide portion has an inclined portion having an inclination angle being substantially the same as an inclination angle of an inclined of the cutting blades. Still further preferably, the cutting blades are formed by edges of cut ends obtained when the electrically conductive plate member is bent preferably by a press, and end positions of the edges are aligned with a starting position of the contact portion. Still further preferably, at least one opening is formed in a portion of a bottom portion of the terminal fitting where the insulation displacement contact portion, preferably the contact portion is provided for avoiding a distortion of the terminal fitting which occurs when the insulation displacement contact portion, preferably the contact portion is formed by embossing. Most preferably, an opening is formed in a portion of a bottom portion of the terminal fitting where the contact portion is provided for avoiding a distortion of the terminal fitting which occurs when the contact portion is formed by embossing. Accordingly, the distortion which occurs when the contact portion is formed by embossing can be avoided by the presence of the opening. According to the invention, there is further provided a method for producing a terminal fitting, in particular according to the invention, comprising the steps of: providing at least one insulation displacement contact portion electrically connectable with a core of an insulated wire by making cuts in an insulation coating as the insulated wire is pushed into the insulation displacement contact portion, wherein the providing step comprises a step of embossing one or more substantially opposing side walls of the terminal fitting inward such that embossed portions substantially have a triangular cross section thereby forming one or more cutting blades for making cuts in the insulation coating of the insulated wire and one or more contact portions which are provided below or behind the cutting blades as seen in an insertion direction of the insulated wire to be brought into contact with the core, said method characterized in further comprising the step of providing of at least one guide portion for guiding the wire to the insulation displacement contact portion above the insulation displacement contact portion, wherein the guide portion has an inclined portion having an inclination angle being substantially the same as an inclination angle of an inclined portion of the cutting blades. According to a further preferred embodiment, the method further comprises a step of bending an electrically conductive plate member and/or plating a front surface plated of a portion thereof. These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings in which: FIG. 1 is a perspective view partly in section of a (cramping or insulation displacement) terminal fitting according to one embodiment, FIG. 2 is a side view of the cramping terminal fitting, FIG. 3 is a plan view of the cramping terminal fitting, FIG. 4 is a plan view of a portion of an electrically conductive plate member near IDC portions of the cramping terminal fitting before bending, FIG. 5 is a perspective view partly in section of the IDC portions, FIG. 6(A) is a section along A-A of FIG. 2, and FIG. 6(B) is an enlarged plan view of a cutting blade, FIG. 7 is a section along B-B of FIG. 2, FIG. 8 is a section showing a state before an insulated wire is mounted in the IDC portion, FIG. 9 is a section showing an intermediate state of the mounting of the insulated wire in the IDC portion, FIG. 10 is a section showing of a state after the insulated wire is mounted in the IDC portion, FIG. 11 is a perspective view of a prior art cramping terminal fitting, and FIG. 12 is a section along C-C of FIG. 11. Next, one embodiment of the invention is described in detail with reference to FIGS. 1 to 10. A (cramping or insulation displacement) terminal fitting 1 formed e.g. by bending an electrically conductive plate member 13 having its front surface plated preferably after stamping it by a press. A connecting portion 2 substantially in the form of a rectangular column connectable with an unillustrated mating terminal fitting is provided at a front part (upper right side in FIG. 1) of the cramping terminal fitting 1. At a rear part of the cramping terminal fitting 1, preferably a pair of barrel portions 4 to be crimped or folded and fastened to an insulation coating 3A of an insulated wire 3 (Hereinafter, "wire 3") project upward from left and right side walls 5 preferably in longitudinally substantially offset positions. Further, one or more insulation displacement contact (IDC) portions 6 to be electrically connected with a core 3B of the wire 3 by making cuts in the insulation coating 3A as the wire 3 is pressed thereinto are provided in the middle of the cramping terminal fitting 1. The pair of IDC portions 6 are provided along the forward/backward directions of the cramping terminal fitting 1 and are substantially symmetrically formed on the left and right side walls 5, and grooves 7 into which the wire 3 is or can be pushed are defined in the middle of the IDC portions 6. Further, each IDC portion 6 is comprised of cutting blades 8 for making cuts in the insulation coating 3A of the wire 3, and a contact portion 9 which is provided below the cutting blades 8 and to be connected with the core 3B. As described later, each contact portion 9 is formed by substantially embossing the portions of the left and right side walls 5 in such a manner as substantially to have a triangular horizontal section, so that the core 3B can be substantially tightly held between the opposing ridges or end portions of the contact portions 9. Preferably, the contact portions 9 are contiguous to the cutting blades 8 so as to be substantially continuous therewith, whereby a wire inserted therein can be properly contacted. The cutting blades 8 also have substantially a triangular horizontal cross section. The edges of the cutting blades 8 are slanted in directions away from each other as they extend toward the above so that the an insulation coating 3A of the wires 3 can be smoothly cut. It should be noted that a method for producing the IDC portion 6 is described later. At the left and right side walls 5, guide portions 10 for guiding the wire 3 into clearances between the cutting blades 8 are provided above the cutting blades 8. The bottom ends of the guide portion 10 and the top ends of the cutting blades 8 are spaced apart by small openings 14. Further, the guide portions 10 are formed by embossing the side walls 5 to bulge inward preferably in such a manner as to have a cross section in the form of an isosceles triangle, and ridges in the middle of the guide portions 10 are slanted toward the grooves 7 as they extend toward the bottom. An angle of inclination a of the guide portions 10 and that a' of the cutting blades 8 are substantially the same (FIG. 8), and the inclination of the guide portion 10 and that of the cutting blades 8 follow substantially along the same straight line. Thus, the wire 3 can be more smoothly guided. Further, a pair of longitudinally spaced openings 11 are formed in a bottom wall 12 of the cramping terminal fitting 1 where the contact portions 9 are provided or in a position corresponding thereto. By forming these openings 11, the deformation of the bottom wall 12 can be avoided where the contact portions 9 are formed by embossing the side walls 5. Next, with reference to FIG. 4, a construction of portions to become the IDC portions 6 in the electrically conductive plate member 13 forming the cramping terminal fitting 1 is described. In FIG. 4, the pair of openings 11 are transversely formed in the substantially middle of the plate member 13, and portions to become the IDC portions 6 and the guide portions 10 are provided above and below the respective openings 11. A pair of small openings 14 are provided near the upper and lower ends of the plate member 13 in positions where the openings 11 are formed. The triangular guide portions 10 are embossed in positions more outward than the small openings 14. On the other hand, one first cut 15 is made along the transverse direction of FIG. 4 in a position inward from each small opening 14. Further, a vertically extending second cut 16 in communication with the corresponding small opening 14 is formed substantially in a slightly rightward position of the first cut 15 from the center. In this way, short pieces 17 and long pieces 18 provided at the right and left sides of the second cuts 16, respectively, are formed at portions to become the cutting blades 8 of the IDC portions 6. When the cutting blades 8 are formed, the leading ends of the long pieces 18 (portions to be brought into contact with the second cuts 16) are exposed at positions toward the grooves 7 and the short pieces 17 support the long pieces 18 by being in contact with the rear sides (sides to be brought into close proximity to the side walls 5 in the cramping terminal fitting 1) of the long pieces 18 (see FIG. 6(B)). Thus, edges 18A of the cut ends at the leading ends of the long pieces 18 form the cutting blades 8 for making cuts in the insulation coating 3B of the wire 3. Further, portions between the first cuts 15 and the openings 11 are embossed in the same direction as the guide portions 10 to become the contact portions 9. Since the contact portions 9 have no cut ends obtained e.g. by being stamped by the press, plating is held as it is at their front surfaces. Further, the end positions of the edges 18A and the starting positions of the contact portions 9 (which are opposed to each other via the first cuts 15) are aligned. Next, the action and effects of this embodiment are described with reference to FIGS. 8 to 10. First, as shown in FIG. 8, an end of the wire 3 is positioned substantially above the IDC portions 6 preferably while the extension of the wire 3 is substantially aligned with the forward/backward directions of the cramping terminal fitting 1. Next, the wire 3 is pushed into the grooves 7. At this time, if the wire 3 is displaced toward one of the left and right side walls 5, the wire 3 is guided toward the grooves 7 by the guide portions 10. Thus, the wire 3 can be smoothly pushed in. When the wire 3 reaches the cutting edges 8 of the IDC portions 6 in this way, cuts are made in the insulation coating 3A by the edges 18A (see FIG. 9). As the wire 3 reaches the contact portions 9, the insulation coating 3A is cut until the contact portions 9 are brought into contact with the core 3B. The wire 3 is pushed to a specified position with the contact portions 9 and the core 3B being held in contact with each other (see FIG. 10). As described above, according to this embodiment, the insulation coating 3A is cut by the cutting blades 8 by pushing the wire 3 to the IDC portions 6 of the cramping terminal fitting 1, and the contact portions 9 provided below the cutting blades 8 are brought into contact with the core 3B. Since the contact portions 9 are formed by embossing the opposite side walls 5 of the cramping terminal fitting 1 to bulge inward, a satisfactory contact state can be maintained without peeling the plating applied to the front surface of the electrically conductive plate member 13 forming the cramping terminal fitting 1. Since the wire 3 is guided to the cutting blades 8 by the guide portions 10 when being pushed into the IDC portions 6, the insulation coating 3A thereof can be smoothly cut. Further, since the edges 18A for making cuts in the insulation coating 3A are aligned with the contact portions 9 provided therebelow, the core 3B of the wire 3 having its insulation coating 3A cut can be smoothly brought into contact with the contact portions 9. In addition, since the openings 11 are formed in positions corresponding to the contact portions 9 in the bottom wall 12 of the cramping terminal fitting 1, the distortion of the cramping terminal fitting 1 when occurs when the contact portions 9 are formed by embossing can be avoided. The present invention is not limited to the foregoing embodiment. For example, the following modifications are also embraced by the technical scope of the present invention as defined in the claims. (1) Although the female cramping terminal fitting 1 is illustrated in the foregoing embodiment, the invention may be applied to male cramping terminal fittings. (2) Although the guide portions 10 are provided above the IDC portions 6 in the foregoing embodiment, they may not be provided according to the invention. (3) Although the openings 11 are formed in the bottom wall 12 of the cramping terminal fitting 1 in the foregoing embodiment, they may not be provided according to the invention. (4) Even though the embossed portions are depicted and described as having a pointed triangular cross section, the embossed portions may have according to the invention also a rounded triangular cross section. LIST OF REFERENCE NUMERALS 1 cramping terminal fitting 3 insulated wire 3A insulation coating 3B core 5 side wall 6 insulation displacement contact portion 8 cutting blade 9 contact portion 10 guide portion 11 opening 12 bottom wall (bottom portion) 13 electrically conductive plate member 18A edge

Claims: A terminal fitting (1) which has at least one insulation displacement contact portion (6) electrically connectable with a core (3B) of an insulated wire (3) by making cuts in an insulation coating (3A) as the insulated wire (3) is pushed into the insulation displacement contact portion (6), wherein the insulation displacement contact portion (6) comprises one or more cutting blades (8) for making cuts in the insulation coating (3A) of the insulated wire (3) and one or more contact portions (9) which are provided below or behind the cutting blades (8) as seen in an insertion direction (I) of the insulated wire (3) to be brought into contact with the core (3B), the contact portion (9) being formed by embossing one or more substantially opposing side walls (5) of the terminal fitting (1) inward such that embossed portions substantially have a triangular cross section, and is capable of tightly holding the core (3B) between the opposing ridges of the embossed portions, said terminal fitting characterized in that at least one guide portion (10) for guiding the wire (3) to the insulation displacement contact portion (6) is provided above the insulation displacement contact portion (6), wherein the guide portion (10) has an inclined portion having an inclination angle (a) being substantially the same as an inclination angle (a') of an inclined portion (8) of the cutting blades (8). A terminal fitting according to claim 1, wherein the contact portion (9) is formed by embossing opposing side walls (5) of the terminal fitting (1) inward. A terminal fitting according to one or more of the preceding claims, wherein the terminal fitting (1) is formed by bending an electrically conductive plate member (13) preferably having its front surface plated. A terminal fitting according to one or more of the preceding claims, wherein the guide portion (10) is for guiding the wire (3) to the cutting blades (8), and the guide portion (10) is provided above the cutting blades (8). A terminal fitting according to one or more of the preceding claims, wherein the cutting blades (8) are formed by edges of cut ends obtained when the electrically conductive plate member (13) is bent preferably by a press, and end positions of the edges are aligned with a starting position of the contact portion (9). A terminal fitting according to one or more of the preceding claims, wherein at least one opening (11) is formed in a portion of a bottom portion (12) of the terminal fitting (1) where the insulation displacement contact portion (6), preferably the contact portion (9) is provided for avoiding a distortion of the terminal fitting (1) which occurs when the insulation displacement contact portion (6), preferably the contact portion (9) is formed by embossing. A method for producing a terminal fitting comprising the steps of: providing at least one insulation displacement contact portion (6) electrically connectable with a core (3B) of an insulated wire (3) by making cuts in an insulation coating (3A) as the insulated wire (3) is pushed into the insulation displacement contact portion (6), wherein the providing step comprises a step of embossing one or more substantially opposing side walls (5) of the terminal fitting (1) inward such that embossed portions substantially have a triangular cross section thereby forming one or more cutting blades (8) for making cuts in the insulation coating (3A) of the insulated wire (3) and one or more contact portions (9) which are provided below or behind the cutting blades (8) as seen in an insertion direction (I) of the insulated wire (3) to be brought into contact with the core (3B) said method characterized in further comprising the step of providing of at least one guide portion (10) for guiding the wire (3) to the insulation displacement contact portion (6) above the insulation displacement contact portion (6), wherein the guide portion (10) has an inclined portion having an inclination angle (a) being substantially the same as an inclination angle (a') of an inclined portion (8) of the cutting blades (8). A method according to claim 7, further comprising a step of bending an electrically conductive plate member (13) and/or plating a front surface plated of a portion thereof.

Inventors: AOYAMA MASAHIKO, KOJIMA EIJI, NIMURA KAZUHIKO, AOYAMA, MASAHIKO, KOJIMA, EIJI, NIMURA, KAZUHIKO
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2000
Main classification: H01R4
IPC codes: H01R4