METHOD OF MAKING CONNECTIONS FOR ELECTRIC WIRES IN JUNCTION MEANS AND APPARATUS FOR CARRYING OUT SAID METHOD

Abstract: Method of making electrical connections for electrical wires to connection tabs at their U-shaped slot portions is disclosed. One of the wire ends is connected to an electrical connector and the connector is carried by wire drive means. Connecting portions of the wires are placed on a junction device and a depressing molder presses the wires onto blades of U-shaped slots of connection tabs which stand upright facing with projections of the depressing molder while frictionally holding the another end portions of the electric wires. An excess depression of the wires to the U-shaped slots is prevented by means of holding block projecting out of the mating surface of the junciton device while wires are inwardly pulled against both friction at one end and stretching force given by compression springs.

Description: Field of The Invention This invention relates to a method of making electrical connections between conductors of electrical insulation wires and connection tabs having wire-receiving U-shaped slots with blade surfaces and being fitted in a junction device. The invention relates further to an apparatus for carrying out said method, comprising a wiring carrying means for transporting the electrical insulation wires and a connecting means for connecting the wires with the connection tabs. The method of making wiring connections of the present invention is particularly useful for preparing a wired junction device when plenty of connecting tabs are aligned in a form of multiple linear arrays which are substantially parallel to each other and also their "U"-shaped wire connecting slot portions are aligned in parallel, as often observed in wired multiple junction boxes for use in motor vehicle wiring harness assemblies. According to the method of the present invention reliable connection of the wires to the corresponding connecting tabs is achieved with an excellent degree of productivity. Prior Art U.S. Patent 4,674,819 of Fujitani et al discloses an electric wire branching connector device for forming branch circuits or junctions in a wire harness system. According to the invention two groups of electric wires are connected by a plurality of connecting tabs inserted through holes formed in the substrate of a junction box which was placed between the two groups of electric wires on its both sides. The connection tab has a male electrical terminal portion in one end and at least one wire grip portion on the other end having a U-shaped blade for making electrical contact to the wire passing through it (Fig.2). When the male end portions are aligned in a suitable distance an electrical connector is engaged so the male portions are mated with the corresponding female receptacle terminals in the connector to which the first group of electric wires have been connected (Fig.3). On the opposite side of the substrate of the junction box the other end portions of the connection tabs are aligned in such way that each of their blades is capable of making a direct electrical contact to at least one electric wire selected from the second group of electric wires passing through it (refer to Fig.2 and Fig.3). Harvey et al discloses a connector for use on tape cables in which a metallic tape or tapes are sandwiched between tapes of plastic material. According to the British Patent No.1,076,628 of Harvey et al the tape cable is laid in a channel of the bottom plate so that the portion of the cable at which the connections are to be made is close to the spring projections. The clamp plate for clamping the two mating members, which grip the tape cable therebetween, are fitted together, the top plate being laid over the bottom plate. When the two plates are urged closer, a tensioning means for drawing the tape cable longitudinally between the mating clamping portions draw the cable across the spring projection. A metallic tooth, formed in contact to the top clamping portion, contacts the insulation surface of the cable and further urges together the top and bottom plates and causes the teeth to plough into the still moving cable which is being pressed against the teeth by the spring projections. When the connector is in the fully mated configuration, the teeth have contacted the metallic conductor of the cable and the spring projections maintain forced electrical contact between them. EP-A-0 132 092 discloses a method and an apparatus for manufacturing electrical harnesses. According to this method, the wires are held during the connecting step between two chucks. The connections between conductors of electrical insulated wires and connectors are made by a vertically moving punch and a die, placed in opposite sides of the wire feed path. The apparatus disclosed in EP-A-0 132 092 comprises a wire carrying means for transporting the electrical insulation wires and a connecting means for connecting the wires with connectors. Summary of The Invention According to the present invention, the method comprises the steps of connecting a group of electrical insulation wires to an electrical connector which is maintained in a connector holder; carrying the electrical insulation wires in a horizontal way keeping them in parallel alignement by means of a wire dispensing means which acts on the front end portions of the wires exerting a stretching force using one or several springs, and by means of a friction pinching mechanism acting on the rear ends of wires, until their connecting portions come to a position for being subjected to connecting operation utilizing a connecting means having a depression junction mold and a junction platform which will be mated during the connecting operation; placing each of the parallelly laid electrical insulation wires over each of the mating grooves on the top surface of the junction device which has been placed on the top surface of the junction platform; contacting the insulation surfaces of the electric wires at their connection point with the blade surfaces of the upright standing tabs by ascending the junction platform; making electrical connections between the conductors of the electrical insulation wires and the U-shaped slots of the connection tabs by descending the depression junction mold onto the mating U-shaped slots resulting in a penetration of the electrical insulation of wires by the blades of the slots. According to a further aspect of the present invention, the apparatus for carrying out the above-described method is characterized in that the wire carrying means consists of a pair of carrying belts to which an embracement device is attached, a connector holder placed in a recess of the embracement device, a wire dispenser having a comb-like dispensing mechanism in its top, a pair of holding spindles which pass through the embracement device and which are jointly attached to the connector holder and the wire dispenser, a pair of compression springs which are inserted around each of the rear end portions of the holding spindles between the front wall of the embracement device and a spring stopper at each of the projecting front end portions of the holding spindles. The free end portion of the group of wires which is opposite to the one with an electrical connector, can be terminated in a range beginning at the corner end portion of the wire junction device after connections between wires and connection tabs have been made. For wiring harness assembly of motor vehicles it is a general requirement of circuit designer that the wires should be terminated without surplus length beyond its edge portions. The present invention provides good longitudinal alignment of the electric wires during the process of making connections with connection tabs at their U-shaped slots and the good alignment of the wires offers reliable connection therebetween. Brief Description of the Drawings Fig.1 is a perspective view showing the method of making connections according to the present invention. Fig.2 shows a conventional wire connection tab having a U-shaped slot and a male connection terminal portion. Fig.3 is a cross sectional view illustrating the connection of the tabs with electric wires in the U-shaped slot. Fig.4 is a cross sectional view of the depression connection mechanism in an open configuration characterizing the method of the present invention shown in Fig.1. Fig.5 is also a cross sectional view of the depression connection mechanism of the present invention in a closed configuration corresponding to Fig.4. Fig.6 is a perspective view of the frame of the junction device used in the method of the present invention. Fig. 7 shows a corresponding perspective view of the frame of the junction device used in the method of the present invention after a group of wires have been depressedly connected. Fig.8 illustrates the constituents of the wire carrying means used in the present invention. 1. connection tab 1a. U-shaped slot 1b. male terminal 2. junction device 2a. frame 2b. recess 2c. projection 3. electric wires 4. depression connecting mechanism 4a. bottom plate member 4b. wire depression projection 4c. groove 5. carrier belt 6. holding block 7. embracement device 8. connector holder 9, 9a, 9b. supporting spindle 10. stopper 10a, 10b. stopper 11. compression spring 11a, 11b. compression spring 12. wire dispenser 13. wire dispenser 14. electrical connector 15. wire holder 16. pinching roller 16a. handle 17 . depression connection mechanism 18. junction platform 19. groove 20a, 20b. mating platform 21. mating projection 22. inner cutter blade 23. outer cutter blade Referred Embodiment The method of making connections for a group of electric wires in a junction device of the present invention will now be described in detail by way of example referring to the accompanying drawings. As shown in Fig.1 the method of the present invention includes substantially the following four steps: (1) a wire carrying means consisting of a pair of carrier belts (5a)(5b), a embracement device (7) which is fixedly hung over each of the carrier belts (5a)(5b) respectively in a way that the embracement device has a recess for holding a connector holder (8), a pair of supporting spindles (9a)(9b) which are fixedly attached to each of the corresponding sides of the embracement device and pass through each side-end portions of the connector holder (8), a pair of stoppers attached to each rear end portion of the supporting spindles (9a)(9b), and a pair of compression springs (11a)(11b) placed between the rear surface of the connector holder (8) and each of the stoppers (10a)(10b) respectively. (2) wire aligning means consisting substantially of a comb-like wire dispenser (12) fixedly attached to the front end portions of the supporting spindles (9a)(9b), and another comb-like wire dispenser (13) attached to the front surface of a wire holder (15) located in a upper stream position along the wire drive direction X. (3) a connecting means ( 17 ) consisting of a table (18) on whose top a wire junction device (2) having a plurality of longitudinally parallel grooves for each of the wires to be connected and a plurality of connection tabs (1) for making the desired number of connections with the wires (3) at their U-shaped, bladed slots 1(a) and having a holding block (6) extending upward from the top surface of a (covering) frame of the wire junction device (2) for preventing an excessive compression of the electric wires (3) onto the blades in the U-shaped slots (1a) of the connection tabs (1); a junction mold (4) with two mating platforms (20), which will mate with the holding block (6) during depressing the wires (3), wire depressing projection (4b), grooves (4c) along Y direction which is perpendicular to the wire-carrying direction X. Each of the grooves (4c) will mate with corresponding grooves on the surface of the junction device, wherein at least one U-shaped slot (1a) is located in the junction device (2) eliminating contact of the slot or slots (1a) to the bottom surface of the junction mold (4), an ascending/descending mechanism for each of the junction platform (18) and the junction mold (4). (4) a wire clamping mechanism consisting of a pinching roller (16) with handle (16a) and a wire holder (15). The pinching roller (16) of an elastomeric material holds the electric wires (3) adjustably and frictionally oppressing against the top surface of the holder (15) in a way that the wires of different sizes in diameter can be clamped. In general practice a group of suitable number of electrical wires (3) with necessary currency allowance have already been connected to the electrical connector (14). To the carrier belts (5a)(5b) there are attached the embracement device (7) respectively and an electrical connector (14) with wires (3) is placed in the connector holder (8). The carrier belts are driven in a synchronous movement to direction X keeping both the clamping mechanism and the wire junction means out of application to the wires (3) until the connector (14) in the holder (8) reaches point H which is located near to the wire junction means (2). The wire clamping mechanism now works in such manner that the connector holder (8) can proceed against the friction caused by the pinching roller (16) and the insulation layer of the electric wires (3) keeping them in an parallel alignment by means of two comb-shaped wire dispensers (12)(13). When the wires (3) are placed in a position described in Fig 1, the connecting means are applied. An example of making junction to the wires is shown through Fig.2 to Fig.5. A wire junction device (2) usually has a multi-layered structure in which several groups of wires are connected independently to the U-shaped slots of connection tabs within a layer. For the reason of description simplicity, an overside perspective views of mono-layered junction device are shown in Fig.4 and Fig.5. In Fig.4 projections and recesses are formed side by side within a line of wire supporting structure on the top surface of the junction device (2). A group of recesses are aligned to form a common straight line in which electrical wires to be connected are placed in the longitudinal direction X. Those wire lines are aligned in pitches corresponding to those of the electrical terminals of a mating electrical connector or connectors to which wires are to be connected through connection tabs (1). In the grooves (19) between the above described wire holding structure there are U-shaped slots (1a) and connection tabs (1) projecting vertically through the bottom of the frame (2a) of the junction device (2) with their blades on the wire passway. Each of the group of electric wires (3) can be fitted with the blade portion of the U-shaped slot (1a) as illustrated in Fig.5. When a group of wires are placed as shown in Fig.1 the junction platform (18) ascends in such a way that the wires (3) to be connected will come into mating engagement with each of the bladed U-shaped slots (1a) of the connection tabs (1) which are standing upright out of the frame (2a) of the junction device (2). The depression molder (4) now descends and its wire depressing projection (4b) depress the mating wire portions downward until the descending movement is terminated by the holding blocks (6) located on the top surface of the bottom plate (18). As shown in Fig.3 the wires (3) are always stretched in the X direction due to the compression spring (11) and they are frictionally supported by the pinching roller (16). They are, therefore, forcedly pulled inwardly during the junction operation eliminating wire damages due to an excessive stretch and also preventing wire from misalignment caused by an excess release of them. According to the method of making connections of the present invention the electric wires are in an excellent parallel longitudinal alignment and reliable connections between wires and connection tabs in its U-shaped slots are achieved as the wires are frictionally maintained at their one end portions and continuously stretched at their another end portions with spring and further inwardly pulled against the above forces without an excessive downward depression during connecting operation by the junction means.

Claims: A method of making electrical connections between conductors of electrical insulation wires (3) and connection tabs (1) having wire-receiving U-shaped slots with blade surfaces and being fitted in a junction device, said method comprising the steps of: connecting a group of electrical insulation wires (3) to an electrical connector (14) which is maintained in a connector holder (8); carrying the electrical insulation wires (3) in a horizontal way keeping them in parallel alignment by means of a wire dispensing means (5, 7, 9a, 9b, 11a, 11b, 12, 13) which acts on the front end portions of the wires (3) exerting a stretching force using one or several springs (11a, 11b), and by means of a friction pinching mechanism (15) acting on the rear ends of wires, until their connecting portions come to a position for being subjected to connecting operation utilizing a connecting means (17) having a depression junction mold (4) and a junction platform (2a) which will be mated during the connecting operation; placing each of the parallelly laid electrical insulation wires (3) over each of the mating grooves (26) on the top surface of the junction device (2c) which has been placed on the top surface of the junction platform (2a); contacting the insulation surfaces of the electric wires (3) at their connection point with the blade surfaces of the upright standing tabs (1) by ascending the junction platform (2a); making electrical connections between the conductors of the electrical insulation wires (3) and the U-shaped slots of the connection tabs (1) by descending the depression junction mold (4) onto the mating U-shaped slots resulting in a penetration of the electrical insulation of wires by the blades of the slots. Apparatus for carrying out the method according to claim 1, comprising a wire carrying means (5, 7, 9a, 9b, 11a, 11b, 12, 13, 15) for transporting the electrical insulation wires (3) and a connecting means (17) for connecting the wires with connection tabs (1), characterized in that the wire carrying means (5, 7, 9a, 9b, 11a, 11b, 12, 13, 15) consists of a pair of carrying belts (5a, 5b) to which an embracement device (7) is attached, a connector holder (8) placed in a recess of the embracement device (7), a wire dispenser (12) having a comb-like dispensing mechanism in its top, a pair of holding spindles (9a, 9b) which pass through the embracement device (7) and which are jointly attached to the connector holder (8) and the wire dispenser (12), a pair of compression springs (11a, 11b) which are inserted around each of the rear end portions of the holding spindles (9a, 9b) between the front wall of the embracement device (7) and a spring stopper (10a, 10b) at each of the projecting front end portions of the holding spindles (9a, 9b). An apparatus according to claim 2, wherein the connecting means (17) consists of: a junction platform (2a) on which the junction device (2c) with connection tabs (1) is placed and which will ascend up to such a level that U-shaped slot portions of the connection tabs (1) are touched by the wire insulation surface hanging over the tabs; and a junction mold (4) which will descend down to a level until it is mated with holding blocks (6) on the surface of the junction device while its linear arrays of alternating projections and recesses depress wires which lie underneath respectively.

Inventors: FUKUDA, MICHIO, OGAWA, FUJIO
Applicants: SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1988
Main classification: H01R43
IPC codes: H01R43