A female terminal metal fittings and a preparing method thereof

Abstract: A female terminal has a front portion adapted to receive a male terminal corresponding thereto, a rear portion adapted to receive and make electrical contact with an electric cable comprising a conductive core surrounded by an insulative sheath, and at least one resilient contact in said front portion into which said male terminal is adapted to be inserted, said resilient contact having an extremity comprising a first and a second main surface located opposite to each other, said first main surface being formed as an even plane and said second main surface being formed as a plane chamfered in the direction toward said first main surface for contacting a bottom plate of said female terminal, thereby forming a sliding contact at a contact point with said bottom plate.

Description: The present invention is directed to female terminals equipped with resilient contacts having two point fulcrums and a method for their manufacture. A typical female terminal of the type improved by the present invention (and disclosed, e.g., in EP-A- 0 313 253, EP-A- 0 661 775 and DE-U- 9 015 110) is shown in Figures 6, 7, and 8. The terminal comprises insulative and wire barrels 1 connected to barrel fitting 2 which contains resilient contact 3 and roof plate 5. Contact 3 is formed from bottom plate 4 and extends through curved portion 6 and ends in extremity 3a. The male terminal (not shown) is inserted in the space between contact 3 and roof plate 5. When this is done, pressure is exerted on contact 3 forcing it in the direction of bottom plate 4. Thus, contact 3 is supported both by curved portion 6 and extremity 3a, thereby providing a reliable spring force which securely holds the male terminal in place. However, in order that the device function satisfactorily, it is necessary that extremity 3a slides smoothly along bottom plate 4. If this is accomplished, the bending movement of contact 3 is not obstructed and suitable connections between the female terminal and the male terminal can be made. In order to accomplish this, as shown in Figure 7, contact 3 was bent upward at extremity 3a. However, this curvature is difficult to produce and, hence, the cost of the part is substantially increased. In fact, it is usually necessary that the extremity be extended as at 3b in Figure 8. EP-A- 0 313 253 discloses a female terminal according to the preamble of present claim 1. It is an object of the present invention to provide a female terminal with an extremity which is capable of sliding smoothly along the bottom plate, thereby facilitating connection and disconnection without concern as to the extremity catching thereon. The foregoing object is achieved by a female terminal according to claim 1 having a front portion adapted to receive a male terminal, and a rear portion adapted to be attached to an electrical cable. The rear portion can include an insulation barrel, which is press-fitted around the sheath of the cable, and a wire barrel which is pressfitted around the electrically conductive core, thereby making electrical contact therewith. The front portion, which receives the complementary male terminal, contains a resilient contact with a curved portion and an extremity comprising first and second main surfaces located opposite to each other and an end portion. The latter bears against the bottom plate of the front portion. Thus, when the male terminal is inserted between the resilient contact and the roof plate, the resilient, contact is urged toward the bottom plate and the end portion of said extremity slides thereon. The point at which the end portion of the extremity contacts the bottom plate is rounded so that there is no edge which can catch or dig into the bottom plate. In order to form the end portion with rounded corner, a flat plate is first cut of in the usual manner. Thereafter, it is placed in a suitable die having a curved portion. Pressure is exerted and the curved portion forces a corner of the end portion of the extremity into the rounded configuration. By carrying out the manufacture in the foregoing two stages, it can be done readily and at reduced cost. It is much easier to press-form than it is to bend. Moreover, excessive unwanted distortion of the resilient contact is substantially avoided. The resultant extremity is capable of sliding easily and reliably on the bottom plate, whereby any catching or scraping of the plate by the extremity is avoided. According to one aspect of the present invention, the resilient contact is bent in an angle of more than a half circular arc (180°) in total so that when the male terminal is introduced into the front portion the second main surface of the extremity slides in a first direction toward the male terminal and contacts the bottom plate with its rounded corner. Therefore, the extremity can be arranged at the front portion. According to another aspect of the present invention, the resilient contact is bent in an angle of less than a half circular arc (180°) in total so that when the male terminal is inserted into the front portion the second main surface of the extremity slides in a second direction away from the male terminal and contacts the bottom plate with its rounded corner. Therefore, the extremity can be arranged at the rear portion. According to another aspect of the present invention, the front portion has a roof plate, the resilient contact being spaced apart from the roof plate by a distance less than a thickness of the male terminal, whereby, when the male terminal is introduced into the front portion, the resilient contact is moved toward the bottom plate and the rounded corner slides on the bottom plate. Therefore, a solid mechanical and electrical contact between the male terminal and the femal terminal is provided. According to another aspect of the present invention, two resilient contacts are provided, said resilient contacts being spaced apart from each other by a distance less than a thickness of said male terminal, whereby, when the male terminal is introduced into the space between the resilient contacts, each resilient contact is moved toward the bottom plate and each rounded corner slides on the bottom plate. Therefore, a female terminal having a symmetrical structure can be provided, the manufacturing and handling of which is simplified. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, constituting a part hereof, and in which like reference characters indicate like parts, Figure 1 is a schematic sectional view of the device of the present invention; Figure 2 is an enlarged section of the resilient contact; Figures 3(A), 3(B), and 3(C) are schematic views in section showing the formation of the rounded corner of the end portion of the extremity of the resilient contact; Figure 4 is a view similar to that of Figure 1 of another embodiment of the present invention; Figure 5 is an enlarged sectional view of the extremity of the contact shown in Figure 4; Figure 6 is a view similar to that of Figure 1 of a prior art device; Figure 7 is a view similar to that of Figure 2 of the prior art device of Figure 6; and Figure 8 is a view similar to that of Figure 7 of another prior art form of the resilient contact. DETAILED DESCRIPTION OF THE INVENTION Referring first to Figures 1 and 2, female terminal 11 comprises insulation barrel 12, wire barrel 13, and barrel fitting 17. Insulation barrel 12 is press-fitted around the insulative sheath of the conductive wire cable (not shown). Similarly, wire barrel 13 grips - and makes electrical contact with - the conductive core of the cable (not shown). Barrel fitting 17 contains roof plate 25, bottom plate 19, and resilient contact 18 located therebetween. Between contact 18 and plate 25 is a space into which male contact 16 of male terminal 15 is inserted. When this is done, resilient contact 18 is pressed toward bottom plate 19. As a result, it is necessary that extremity 20 slides on bottom plate 19 easily and without catching or digging in. To prevent this unwanted possibility, an end portion 21 having a rounded corner is provided in extremity 20, as is best shown in Figure 2. Thus, resilient contact 18 is supported by bent part 26 and extremity 20, but is also capable of sliding motion on bottom plate 19. The formation of said end portion 21 on extremity 20 is shown in Figure 3. Figure 3(A) is a sectional view of metal plate 23 prior to formation of the desired rounded corner. Plate 23 is placed between upper die 31 and lower die 32, as shown in Figure 3(B), and the excess metal is trimmed off, thereby creating sheared surface 24. The rounded corner is formed by placing plate 23 between upper die 34 and lower die 33. Upper die 34 is provided with arcuate surface 35 which, upon exertion of pressure urging dies 33 and 34 toward one another, rounds off the corner and creates end portion 21 having said rounded corner. Another embodiment of the present invention is shown in Figures 4 and 5. As to Figure 4, the barrels for attaching the terminal to a wire cable are omitted for clarity. Female terminal 41 includes barrel fitting 43 carrying roof plate 47, and resilient contact 42. The shape thereof is somewhat different from that of Figure 1, but end portion 48 having said rounded corner is provided on the corresponding portion of resilient contact 42. The male terminal (not shown) is inserted into the space between resilient contact 42 and roof plate 47. This forces resilient contact down so that extremity 45 bears against bottom plate 44. In Figure 5, said end portion 48 has been provided on extremity 45 in a manner analogous to that of Figures 3.

Claims: A female terminal (11; 41) having a front portion adapted to receive a male terminal (15) corresponding thereto, a rear portion adapted to receive and make electrical contact with an electric cable comprising a conductive core surrounded by an insulative sheath, and at least one resilient contact (18; 42) in said front portion into which said male terminal (15) is adapted to be inserted, said resilient contact having an extremity (20; 45) comprising first and second main surfaces located opposite to each other and a rounded end portion (21; 48), said end portion (21;48) being able to contact a bottom plate (19; 44) of said female terminal, thereby forming a sliding contact at a contact point with said bottom plate (19; 44), characterized in that said end portion (21; 48) has been formed by press-forming and the comer thereof which is to form said sliding contact at the contact point with said bottom plate (19; 44) is rounded. The female terminal according to claim 1, wherein the resilient contact (18) is bent in an angle of more than a half circular arc (180°) in total so that when said male terminal (15) is introduced into said front portion said end portion (21) of said extremity (20) slides in a first direction toward said male terminal and contacts said bottom plate (19). The female terminal according to claim 1, wherein the resilient contact (42) is bent in an angle of less than a half circular arc (180°) in total so that when said male terminal (15) is inserted into said front portion said end portion (48) of said extremity (45) slides in a second direction away from said male terminal and contacts said bottom plate (44). The female terminal according to any of the preceding claims, wherein said front portion has a roof plate (25; 47), said resilient contact (18; 42) being spaced apart from said roof plate by a distance less than a thickness of said male terminal (15), whereby, when said male terminal (15) is introduced into said front portion, said resilient contact (18; 42) is moved toward said bottom plate (19; 44) and said end portion (21; 48) slides on said bottom plate (19; 44). The female terminal according to any of the claims 1 to 3, wherein two resilient contacts (18; 42) are provided, said resilient contacts being spaced apart from each other by a distance less than a thickness of said male terminal (15), whereby, when said male terminal is introduced into the space between said resilient contacts, each resilient contact (18; 42) is moved toward said bottom plate (19; 44) and each end portion (21; 48) slides on said bottom plate (19; 44). A method for manufacturing a female terminal (11; 41) according to any of the preceding claims, said method comprising cutting a resilient plate (23) to form said resilient contact (18;42) having an edge (24) a said contact point and then press-forming said edge (24), thereby forming said end portion (21;48) having a rounded corner thereon.

Inventors: NAKATA HIROYUKI, OKADA HAJIME, NAKATA, HIROYUKI, OKADA, HAJIME, NAKATA, HIROYUKI, C/O SUMITOMO WIRING SYST., LTD., Okada, Hajime, c/o Sumitomo Wiring Syst., Ltd.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1996
Main classification: H01R13
IPC codes: H01R13, H01R43