A terminal fitting

Abstract: During crimping, after being held tense, first and second crimping pieces 11, 12 are curved such that leading edges 11A, 12A thereof are inclined inwardly to reduce a diameter, which is then crimped into connection with a wire W. Since the second crimping piece 12 is formed with a deformation facilitating portion 15 for facilitating such bending as to incline the leading edge 12A inwardly by being partly thinned at a position along its extending direction, the leading edge 12A can be securely bent inwardly. Thus, a crimping error resulting from such a deformation as to incline the leading edge 12A in a direction opposite from an intended one can be prevented from occurring.

Description: The present invention relates to a terminal fitting to be crimped into connection with a wire. A terminal fitting disclosed in Japanese Unexamined Patent Publication No. 4-209471, which in considered as the closest prior art, according to the preamble of claim 1, is known as the one to be crimped into connection with a wire. As shown in FIGS. 9 to 13, a wire fastening portion 101 of this terminal fitting 100 is a so-called barrel portion in which first and second fastening pieces 103, 104 extend upward from the left and right side edges of a bottom wall 102. An automated apparatus is used to crimp the wire fastening portion 101 into connection with a wire 105. First, as shown in FIG. 9, with the wire fastening portion 101 placed on an anvil 106 and the wire 105 placed between the two fastening pieces 103, 104, a crimper 107 located thereabove and provided with an arch-shaped guide surface 108 formed with a stepped stopper 109 substantially at the uppermost position is lowered. During the lowering process, a leading end 103A of the first crimping piece 103 comes into contact with the stopper 109 to be held tense, and a leading end 104A of the second crimping piece 104 comes into contact with the leading end 103A of the first crimping piece 103 to be held tense (see FIG. 10). Thereafter, the first and second crimping pieces 103, 104 are bent such that their leading ends 103A, 104A are inclined inwardly, which causes the first crimping piece 103 to depart from the stopper 109 and be bent along the guide surface 108 to decrease a radius of curvature while causing the second crimping piece 104 to be bent along the inner side surface of the first crimping piece 103 to decrease a radius of curvature. As a result, the bottom wall 102, the first and second crimping pieces 103, 104 are crimped to be fastened to the outer circumferential surface of the wire 105. In the crimping terminal fitting 100 as above, the leading end 104A of the second crimping piece 104 may be so bent as to incline in a direction opposite from an intended bending direction as shown in FIGS. 11 and 12 and may be finally folded back as shown in FIG. 13. If this occurs, the folded leading end 104A may be broken along a line of fold and come out through a clearance between the first crimping piece 103 and the wire 105. As a result, a clearance may be formed between the first crimping piece 103 and the wire 105, resulting in a reduced fastening force. Such a problem is particularly prominent in terminal fittings in which a projection 110 is formed on the inner side surface of the second crimping piece 104 as a means for strengthening a fastening force so that this projection 110 bites in the outer circumferential surface of the wire 105. US-A-5 635 676 discloses a H-tap compression connector, comprising upper and lower conductor receiving nests with generally U-shaped inner surface. Each conductor receiving nest is defined by a bottom wall and a pair of opposed outstanding walls, which are deformed inwardly by a crimping tool. In order to assure overlapping of one of the sidewalls over the other upon crimping, a weakened portion is provided on one of the sidewalls, in form of a grooves extending along the inner surface thereof. The object of the present invention is to secure crimp crimping pieces into connection with a wire. This object is solved according to the invention by a terminal fitting according to claim 1. Preferred embodiments of the invention are object of the dependent claims. According to the invention, there is provided a terminal fitting comprising a wire fastening portion having a bottom wall, and at least first and second crimping pieces extending from the bottom wall, the wire fastening portion being crimpable into connection with a wire such that the second crimping piece is deformed to reduce a radius of curvature while moving substantially along the inner side surface of the first crimping piece so as to fasten the first and second crimping pieces substantially around the outer circumferential surface of the wire, wherein the second crimping piece is recessed to form a deformation facilitating portion or a weakened portion for facilitating bending or deforming to incline a leading end portion of the second crimping piece inwardly. The second crimping piece can securely undergo a proper deformation to incline its leading edge inwardly by forming the deformation facilitating portion. Thus, a crimping error resulting from such a deformation as to incline the leading edge in a direction opposite from an intended one can be prevented from occurring. According to a preferred embodiment of the invention, there is provided a terminal fitting comprising a wire fastening portion having a bottom wall, first and second crimping pieces extending from the opposite side ends of the bottom wall, the wire fastening portion being crimped into connection with a wire such that the second crimping piece is deformed to reduce a radius of curvature while moving along the inner side surface of the first crimping piece so as to fasten the first and second crimping pieces around the outer circumferential surface of the wire, wherein the second crimping piece is recessed in a portion located along its extending direction to form a deformation facilitating portion for facilitating bending to incline a leading end of the second crimping piece inwardly. Preferably, a projection (which can preferably bite in the outer circumferential surface of the wire in particular when the wire fastening portion is crimped into connection with the wire) is formed on the inner side surface of the second crimping piece, and the deformation facilitating portion is formed in a position closer to the leading end (portion) of the second crimping piece than the projection. The second crimping piece is bent at the position (position of the deformation facilitating portion) closer to its leading edge than the projection to thereby incline the leading edge inwardly. Angles of inclination of the bent leading end with respect to a guide surface and the first crimping piece are smaller as compared to a case where the second crimping piece is bent at a position closer to a base end opposite from the leading edge than the upper projection. Thus, the second crimping piece is smoothly moved along the inner side surface of the first crimping piece thereafter to reduce a diameter. Further preferably, the deformation facilitating portion is formed by recessing at least one side surface of the second crimping piece into a groove extending along a direction substantially normal to the extension of the second crimping piece. Since the deformation facilitating portion is in the form of a groove extending in a direction normal to the extension of the second crimping piece, i.e. along a bending line, bending can be more securely performed. Still further preferably, the deformation facilitating portion is formed by recessing only the inner side surface of the second crimping piece into the groove. When the leading end of the second crimping piece is bent at the deformation facilitating portion, it is substantially bent about a point on the outer side surface of the second crimping piece corresponding to deformation facilitating portion 15. Since the groove is open in the inner side surface, there is no likelihood that the opening edge of the groove gets caught by the inner side surface of the first crimping piece and the guide surface while the second crimping piece is deformed to reduce a diameter as crimping progresses. Further preferably, the deformation facilitating portion is formed by thinning the second crimping piece, e.g. by stretching a metal plate used for the production of the terminal fitting.. Most preferably, the bottom wall is formed with at least one bottom projection for coming into contact with the wire, preferably biting thereinto. These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings in which: FIG. 1 is a perspective view of a first preferred embodiment of the invention, FIG. 2 is a partial enlarged front view of a second crimping piece, FIG. 3 is a partial enlarged side view of the second crimping piece, FIG. 4 is a front view showing a state before crimping, FIGS. 5 to 7 are front views showing successive states during crimping, FIG. 8 is a front view showing a state after crimping, FIG. 9 is a front view showing a state of a prior art before crimping, FIGS. 10 to 12 are front views showing successive states of the prior art during crimping, and FIG. 13 is a front view showing a state of the prior art after crimping. Hereinafter, a first preferred embodiment of the invention is described with reference to FIGS. 1 to 8. A terminal fitting T of this embodiment is, as shown in FIG. 1, provided at its front end or front end portion with a connection portion Ta for connection with a mating male terminal fitting and at its rear end or rear end portion with a wire fastening portion Tb for connection with a wire W. A mode of the wire fastening portion Tb is described below. The wire fastening portion Tb is comprised of an arcuate bottom wall 10 bulging out downwardly, and first and second fastening pieces 11, 12 extending preferably from lateral left and right side edges of the bottom wall 10. Before being crimped or bent or deformed, the two fastening pieces 11,12 preferably extend substantially straight at an angle different from 0° or 180°, preferably substantially upward from the bottom wall 10 while being slightly oblique to widen a spacing therebetween toward their upper ends. The bottom wall 10 is formed with a first or upward bulging lower projection 13 which is formed by, e.g. cutting a portion of the bottom wall 10 and bending the cut portion up or embossing a portion of the bottom wall 10. The lower projection 13 functions to enhance a fastening force by preferably biting in the bottom of the outer circumferential surface of the wire W during crimping. On the other hand, a second or upper projection 14 bulging out inwardly (direction toward the first crimping piece 11) is formed in a position of the second crimping piece 12 near its leading edge 12A by, e.g. embossing or a combination of cutting and bending. In a crimped state of the wire fastening portion Tb, the upper projection 14 is located to hold the wire W in cooperation with the lower projection 13 and preferably bites in the upper part of the outer circumferential surface of the wire W to enhance a fastening force to the wire W in cooperation with the lower projection 13. The second crimping piece 12 is formed with a deformation facilitating portion (or a weakened portion) 15 for bending or inclining the leading edge 12A inwardly (toward the first crimping piece 11) during crimping. The deformation facilitating portion 15 is formed by partly thinning or cutting or recessing the inner side surface of the second crimping piece 12 to form a straight groove 15A which is continuous along a direction (substantially parallel to a line along which the second crimping piece 12 is bent and/or to the longitudinal direction of the wire W) substantially normal to the extending direction of the second crimping piece 12 from the bottom wall 10. In other words, the outer side surface of the second crimping piece 12 is left as it is by recessing only the inner side surface thereof. The deformation facilitating portion 15 (groove 15A) is located closer to the leading edge 12A than the upper projection 14 and very close to the upper projection 14. Next, an automated crimping apparatus is described. This apparatus includes an anvil 20 and a crimper 25. The anvil 20 is also called a lower mold, and is formed with an arcuate placing surface 21 having a smaller curvature (or a larger radius of curvature) than the bottom wall 10 before crimping. The bottom surface 10 of the wire fastening portion Tb is or can be placed on the placing surface 21. The crimper 25 includes a pair of left and right leg portions 26 projecting downward, and a guide surface 27 located between the upper ends of the leg portions 26. The guide surface 27 is so arch-shaped (arcuate) as to substantially correspond to the arcuate shape of the bottom wall 10, and its opposite lateral ends are smoothly tangentially continuous with the inner surfaces of the leg portions 26. A stepped stopper 28 is formed substantially at the uppermost position of the arch-shaped guide surface 27, and a right area 27R (side corresponding to the first crimping piece 11) and a left area 27L (side corresponding to the second crimping piece 12) of the guide surface 27 in FIGS. 4 to 8 extend substantially downward from the stopper 28 while widening a spacing therebetween toward the bottom ends. Accordingly, if the first crimping piece 11 approaches the stopper 28 while sliding on the right area 27R of the guide surface 27, such an approaching movement is restricted by the contact of the crimping piece with the stopper 28. On the other hand, if the second crimping piece 12 approaches the stopper 28 while sliding on the left area 27L of the guide surface 27, it is permitted to enter the right area 27R after passing the stopper 28 without getting caught. Next, a crimping operation is described. First, as shown in FIG. 4, the wire fastening portion Tb is placed on the placing surface 21 of the anvil 20, and the wire W is supplied at least partly between the crimping pieces 11, 12 to be placed on the bottom wall 10. The crimper 25 is lowered or moved toward the anvil 20 in this state. While the crimper 25 is being lowered, the leading edges 11A, 12A of the crimping pieces 11, 12 are first brought into sliding contact with the inner surfaces of the leg portions 26, and then displaced inwardly (directions toward the mating crimping pieces) by further sliding on the guide surface 27. Consequently, the first crimping piece 11 is held tense or chucked by its leading edge 11A coming into contact with the stopper 28 (see FIG. 5), whereas the second crimping piece 12 is held tense by its leading edge 12A coming into contact with the inner side surface of a leading end portion 11B of the first crimping piece 11 (shown in phantom in FIG. 5). At this time, the crimping pieces 11, 12 are substantially straight without being curved or bent. Thereafter, as the crimper 25 is further lowered or moved toward the anvil 20, the second crimping piece 12 is first bent such that its leading edge 12A is inclined or deformed inwardly substantially about the position of the deformation permitting portion 15 (at a position closer to the leading edge 12A than the upper projection 14) (shown in solid line in FIG. 5). At this time, the deformation permitting portion 15 projects outward or is bent outwardly (i.e. toward the side away from the first crimping piece 11 and closer to the left area 27L of the guide surface 27). Subsequently, as shown in FIG. 6, the second crimping piece 12 is bent outwardly (in a direction toward the left area 27L of the guide surface 27) at its position closer to its base end (side toward the bottom wall 10 and opposite from the leading edge 12A) than the upper projection 14, and the first crimping piece 11 is bent outwardly (in a direction toward the right area 27R of the guide surface 27) at its substantially center position with respect to its extending direction or height direction. At this time, the bent portions of the crimping pieces 11, 12 substantially come into contact with the right and left areas 27R, 27L, respectively. By this bending, the leading end portion 11B of the first crimping piece 11 is displaced to have such an orientation as to extend substantially along the guide surface 27. This change of the orientation causes the leading edge 11A of the first crimping piece 11 to move radially inward or toward the wire W (downward in FIG. 6) from the stopper 28, coming into sliding contact with the left area 27L and slipping between the guide surface 27 and the second crimping piece 12. Accordingly, the first crimping piece 11 is curved along the guide surface 27 as a whole, decreasing a radius of curvature (see FIG. 7). Further, a leading end 12B (portion closer to the leading edge 12A than the deformation facilitating portion 15) of the second crimping piece 12 is oriented to extend along the guide surface 27. By this change of the orientation, the leading end 12B of the second crimping piece 12 slides on the inner side surface of the first crimping piece 11 toward the bottom wall 10 (toward the side opposite from the leading edge 11A of the first crimping piece 11). Accordingly, the entire second crimping piece 12 is so curved along the inner (circumferential) surface of the first crimping piece 11 and the guide surface 27 as to decrease a radius of curvature (see FIG. 7). The bottom wall 10, the first and second crimping pieces 11, 12 are crimped to be fastened to the outer circumferential surface of the wire W, and the upper and lower projections 14, 13 bite in the outer circumferential surface of the wire W, with the result that the wire fastening portion Tb of the terminal fitting T is crimped into connection with the wire W (see FIG. 8). As described above, in this embodiment, the second crimping piece 12 is formed with the deformation facilitating portion or weakened portion 15 for facilitating such bending or deformation as to incline the leading edge 12A inwardly by partly thinning the second crimping piece 12 at the portion located along its extending direction. Thus, the second crimping piece 12 is securely deformed as intended to incline the leading edge 12A inwardly. Therefore, the leading end 12B will not undergo such a deformation as to be folded in a direction different from the intended one on the outer side surface of the second crimping piece 12, which in turn prevents a crimping error resulting from such an unintended deformation. Formation of the deformation facilitating portion 15 in the position closer to the leading edge 12A advantages than the upper projection 14 brings about the following. Specifically, the second crimping piece 12 is bent at the position (deformation facilitating portion 15) closer to the leading edge 12A than the upper projection 14 to thereby incline the leading edge 12A inwardly. In this case, angles of inclination of the bent leading end 12B with respect to the guide surface 27 and the first crimping piece 11 are smaller as compared to a case where the second crimping piece 12 is bent at a position closer to the base end (bottom wall 10) opposite from the leading edge 12A than the upper projection 14. In other words, in this embodiment, the leading end 12B bent at the deformation facilitating portion 15 is oriented more parallel to the guide surface 27 and the leading end 11B of the first crimping piece 11 as compared to the one bent at the position closer to the base end than the upper projection 14. Thus, the second crimping piece 12 is smoothly moved along the inner side surface of the first crimping piece 11 to reduce a diameter after bending. Since the deformation facilitating portion 15 is in the form of a groove preferably extending in a direction substantially normal to the extension of the second crimping piece 12, i.e. along a bending line, bending can be more securely performed. Further, since the deformation facilitating portion 15 is a groove formed only in the inner side surface of the second crimping piece 12, the leading end 12B of the second crimping piece 12 is bent at the deformation facilitating portion 15 substantially about a point on the outer side surface of the second crimping piece 12 corresponding to deformation facilitating portion 15. In case the groove 15A is open in the inner side surface, there is no likelihood that the opening edge of the-groove 15A gets caught by the inner side surface of the first crimping piece 11 and the guide surface 27 while the second crimping piece 12 is deformed to reduce a diameter as crimping progresses. The present invention is not limited to the above described illustrated embodiment. For example, following embodiments are also embraced by the technical scope of the present invention as defined in the claims. Besides them, various changes can be made without departing from the scope of the present invention as defined in the claims. (1) Although the female terminal fitting is described in the foregoing embodiment, the present invention is applicable to male terminal fittings. (2) Although the second crimping piece is formed with the projections for strengthening the fastening force to the wire in the foregoing embodiment, the present invention is applicable to terminal fittings having no such projection. (3) Although the deformation facilitating portion is a continuous recess in the form of a groove in the foregoing embodiment, it may be formed by a plurality of recesses discontinuously present substantially along a direction normal to the extension of the second crimping piece according to the present invention. (4) Although the deformation facilitating portion is recessed only in the inner side surface of the second crimping piece in the foregoing embodiment, only the outer side surface of the second crimping piece may be recessed or both the inner and the outer side surfaces thereof may be recessed according to the present invention. (5) Although the deformation facilitating portion is provided only in one position in the foregoing embodiment, it may be provided in a plurality of positions spaced apart along the extension of the second crimping piece. LIST OF REFERENCE NUMERALS T terminal fitting Tb wire fastening portion W wire 10 bottom wall 11 first crimping piece 12 second crimping piece 14 upper projection (projection) 15 deformation facilitation portion 20 anvil 25 crimper 27 guide surface 28 stopper

Claims: A terminal fitting (T) comprising a wire fastening portion (Tb) having a bottom wall (10), and at least first and second crimping pieces (11, 12) extending from the bottom wall (10), the wire fastening portion (Tb) being crimpable into connection with a wire (W) such that the second crimping piece (12) is deformed to reduce a radius of curvature while moving substantially along the inner side surface of the first crimping piece (11) so as to fasten the first and second crimping pieces (11, 12) substantially around the outer circumferential surface of the wire (W), characterized in that the second crimping piece (12) is recessed to form a deformation facilitating portion (15) for facilitating bending to incline a leading end portion (12B) of the second crimping piece (12) inwardly and an inner side surface portion of a leading end portion (11B) of the first crimping piece (11) is tapered outwardly and the outer side surface portion of the leading end portion (12B) of the second crimping piece is tapered inwardly. A terminal fitting according to claim 1, wherein at least one projection (14) is formed on the inner side surface of the second crimping piece (12), and the deformation facilitating portion (15) is formed in a position closer to the leading end portion (12B) of the second crimping piece (12) than the projection (14). A terminal fitting according to claim 2, wherein the projection (14) is formed such that it can bite in the outer circumferential surface of the wire (W) when the wire fastening portion (Tb) is crimped into connection with the wire (W). A terminal fitting according to one or more of the preceding claims, wherein the deformation facilitating portion (15) is formed by recessing at least one side surface of the second crimping piece (12) into at least one groove (15A) extending along a direction substantially normal to the extension of the second crimping piece (12). A terminal fitting according to claim 4, wherein the deformation facilitating portion (15) is formed by recessing only the inner side surface of the second crimping piece (12) into the at least one groove (15A). A terminal fitting according to one or more of the preceding claims, wherein the deformation facilitating portion (15) is formed by thinning the second crimping piece (12). A terminal fitting according to one or more of the preceding claims, wherein the bottom wall (10) is formed with at least one bottom projection (13) for coming into contact with the wire (W), preferably biting thereinto.

Inventors: KOIDE TAKASHI, KOIDE, TAKASHI, Koide, Takashi, c/o Sumitomo Wring Systems, Ltd.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2001
Main classification: H01R4
IPC codes: H01R4