WO1999014829A1

WO1999014829A1 - Machine and method for preparing twisted conductor leads

Info

Publication number: WO1999014829A1
Application number: PCT/IB1998/001379
Authority: WO
Inventors: Jacques Morote
Original assignee: The Whitaker Corporation
Priority date: 1997-09-15
Filing date: 1998-09-04
Publication date: 1999-03-25
Also published as: AU8818998A

Abstract

A wire twisting device of a harness making machine comprises a pair of rotatable grippers (11) that clamp opposed ends (5a, 5b) of a pair of wire conductors (5) held in a loop. A tensioner member (14) tensions the wire loop during the twisting operation. Both grippers (11) are rotated simultaneously. Provision of the conductor pair and loop during twisting, halves the twisting time, and enables the length of the wires to be doubled.

Description

MACHINE AND METHOD FOR PREPARING TWISTED CONDUCTOR LEADS

This invention relates to a machine for preparing electrical leads terminated to terminals or connectors or pre-prepared for termination or assembly in a cable harness, where wires of the leads are twisted, for example twisted pairs for high speed data signal transmission.

Twisted pair conductors are commonly used in telecommunication systems and local area networks (LAN) for transmitting data signals at high frequency. The use of twisted pair conductors or even braids having three twisted conductors are also used in applications out of the LAN and telecommunication industries. An advantage of twisted pair cable assemblies is their low cost in comparison to coaxial or fibre optic cable assemblies, and are therefore finding uses in the automobile and other industries. Twisted pair cables are sometimes implemented in harnesses of an automobile or other machines or devices requiring cables for high frequency data transmission. One problem with twisted pair cables, is that they are not well adapted for automated termination to terminals or connectors in view of the need to separate and identify conductors of the pair prior to termination. It would also be desirable to incorporate the termination of twisted pair conductors in harness making machines, such that complex harnesses (for example used in automobiles) can be semi-automatically or automatically produced. It is an object of this invention to provide a machine for automatically preparing twisted leads, in particular twisted pair cables which can be easily terminated to connector or terminals. It would be advantageous to have a machine for preparing twisted cables for fully automated production of terminated leads, and that can be incorporated into a harness making machine if desired. It would be particularly advantageous to provide rapid manufacturing times. It would be particularly advantageous to ensure that the lead is twisted in a regular manner such that data signal transmission is reliable at frequencies as high as possible.

Objects of this invention have been achieved by providing the machine according to claim 1, and a method of producing a twisted cable according to claim 9. Disclosed herein is a machine for preparing twisted cables comprising a first cable gripper for gripping an end of a cable comprising at least two wire conductors, and a second cable gripper for gripping another end of the cable, at least one of the grippers being rotatably driven by a motor, the axis of rotation thereof extending substantially parallel to the end of the wire extending from the gripper for twisting the at least two wire conductors about each other for forming a cable comprising multiple twisted conductors, wherein the machine further comprises a cable mid-section support around which the cable extends forming a roughly U-shape, the first and second grippers facing approximately in a direction towards the cable mid-section. Advantageously, at least two conductors can be twisted about each other in an automated manner in a harness making machine, with a relatively compact machine due to bending of the cable about a mid-section support. Also advantageous is the production of a twisted cable from single conductors that can be selected and held at their ends for subsequent termination to terminals or connectors.

The first and second grippers may be arranged adjacent each other and facing in substantially parallel directions such that a particularly compact twisting device is provided. The latter also enables easy access for a pair of grippers simultaneously placing opposed ends of the cable wires into respective grippers. Both grippers may be driven such that the twisting time is reduced by a factor of two. By positioning the grippers adjacent each other and facing the same direction, both grippers can be driven by a single motor, as they both turn in the same direction for twisting the cable. The cable support may be driven by a motor in a direction to and from the grippers for tensioning the cable during the twisting operation. Extension of the conductors around the support, particularly for long cables, reduces vibration of the cable during twisting such that high speed rotation of the grippers does not adversely affect the regularity of the twists. A high speed and compact cable twisting and preparation machine can thus be achieved.

Further advantageous aspects of this invention will be described in the claims or will be apparent from the following description and drawings.

An embodiment of this invention will now be described by way of example with reference to the figures in which; figure 1 is an isometric view of a machine according to this invention, figure 2 is a side view of the machine; figure 3 is a view similar to figure 1 showing a first step in the preparation of a twisted cable; figure 4 is a view similar to figure 3 showing a subsequent step where ends of a pair of conductors are removed from a conveyor supplying wire conductors to a twisting station; figure 5 shows a subsequent step to figure 4 showing the pair of wires about to be positioned in the grippers of the twisting station; figure 6 shows a subsequent step to figure 5 showing positioning of the wires in the grippers; figure 7 shows a subsequent step to figure 6 where the transfer grippers are raised away from the wires held in the twist grippers; figure 8 shows a subsequent step to figure 7 where the cable loop support is moved to tighten the wires; figure 9 shows a subsequent step indicating rotation of the twist grippers; figure 10 shows a subsequent step to figure 9 where the twisted cable is removed from the twist grippers and transported by the cable mid-section support member.

Referring to the figures, particularly figure 1, the machine comprises a chassis or support 1 on which a cable twist device 6 is mounted for twisting two or more wires 5. In the embodiment shown, a pair of single wire conductors 5 are shown transported on a wire supply conveyor 2 having wire grippers 4. The pair of wire conductors 5 are fed and cut to length a wire supply and cutting station. The wires are held in adjacent grippers 4 of the conveyor station 2 proximate opposed first and second ends 5a, 5b which may be terminated to connectors or terminals, which are only schematically shown at 20 in figure 1. Instead of termination to connectors or terminals, it is also possible to provide special clamps that hold the pair of first ends 5a, or the pair of second ends 5b in a fixed relation such that the pair of wires can be twisted relative to each other whilst nevertheless enabling exact selection and location of the wire ends for further processing. Wire ends 5a, 5b can thus be either terminated to connectors or terminals prior to twisting, or after the twisting operation.

As shown in figure 1, a transfer device 8 is movably mounted on a support rail 9 that is fixedly supported on a portion la of the support 1. The transfer device 8 is movably mounted in a sliding direction T for transferring the pairs of wire ends 5a, 5b from the supply conveyor 2, to the cable twist device 6. The transfer device 8 has a pair of transfer grippers 7 that are movably mounted and driven with respect to the transfer member in a vertical direction V. The transfer grippers 7, as well as the supply conveyor grippers 4 can be opened and closed in order to grip or release the wires. The transfer grippers 7 can thus be lowered to grip the ends 5a, 5b and raise the wires 5 out of the conveyor grippers 4 and transfer them to the wire twist device 6, by sliding in the direction T on the rail 9.

The twist device 6 comprises first and second wire twist grippers 11 for clamping respectively the first and second ends 5a, 5b respectively of the two or more wire conductors 5 that are to be twisted together. A guide plate 10 has funnel shaped entry portions 10a for guiding the wire ends 5a, 5b that are released from the transfer grippers 7 into the grippers 11. The twist grippers 11 have jaws that open and close for clamping the wire ends. The first and second grippers 11a, lib are positioned adjacent each other, and are rotatably mounted to a portion 1' of the support 1 about axes of rotation extending in a direction A substantially parallel to the direction of the wire ends 5a, 5b when received in the grippers 11a, lib. Each of the twist grippers 11a, lib is engaged by a motor 12 via transmission belts 12a, 12b, a first belt 12a engaging a toothed shaft 22a of the first twist gripper 11a, and similarly a second toothed belt 12b engaging a toothed shaft 22b of the second twist gripper lib. Both belts 12a, 12b are driven by a toothed shaft 24 of the motor 12. Because the twist grippers 11a, lib are facing in substantially the same direction, they can be rotated in the same angular direction (i.e. clockwise or anti-clockwise) in order to effect the wire twist. Only a single motor 12 is thus needed. The motor 12 may be controlled by a harness making machine that determines the number of revolutions of the motor depending on the pitch of the twists in the wire pair, taking into account the length of the cable.

The wires to be twisted are held in the twist grippers at both ends to form a U-shaped cable with a loop or U- bend 16 remote from the wire ends 5a, 5b. The twist device further comprises a tensioner member 14 movable in an axial direction A substantially parallel to the direction of the axis of rotation of the twist grippers 11a, lib. When the wire pair to be twisted is held in the grippers, the first and second wire ends 5a, 5b are arranged either side of the tensioner member 14, which is moved to an operating position as shown in figure 8 where the wires are taught. Subsequently, the motor 12 is actuated to effect a certain number of revolutions corresponding to the desired wire twist. A base 17 is provided under the wires 5 such that vibration of the wires between the ends 5a, 5b and the loop 16 are dampened. Looping of the wires 5 around the tensioner member 14 (resulting in two branches) also reduces the effective length of the cable by a factor two, and as a consequence longer cables can be twisted at relatively high speed without problems of vibration. Simultaneous twisting of both wires end 5a, 5b by the twist grippers 11a, lib also decreases the cycle time of twisting by a factor two. A particularly high speed and relatively compact machine for twisting wire conductors is thus provided. Simultaneous to the twisting operation, the conveyor 2 and transfer device 8 can be operated to prepare supply of a new pair of conductors to the twist device 6. As shown in figure 10, after completion of a twisting operation, the tensioner member 14 can be used to eject or transport the twisted lead away from the twist grippers 11 such that new wire conductors 5' can be positioned in the twist grippers for a subsequent twisting cycle. The tensioner member may be driven in the axial direction by a belt drive or other conventional means interconnected to a motor 15 that may be controlled by the computer of a harness making machine in order to co-ordinate movements.

Claims

1. A machine for preparing twisted cables comprising a first twist gripper (11a) for gripping first ends (5a) of at least two wire conductors (5) , and a second twist gripper (lib) for gripping second ends (5b) of the wires (5) , at least one of the twist grippers (11a, lib) being rotatably driven by a motor (12) about an axis of rotation extending in a direction (A) substantially parallel to the wire ends (5a, 5b) for twisting the at least two wire conductors (5) about each other for forming a twisted multiple conductor cable, wherein the machine further comprises a cable mid-section support (14) around which the wire conductors (5) extend forming a roughly U-shaped loop (16), the first and second twist grippers (11a, lib) facing approximately in a direction (A) towards the mid-section support.

2. The machine of claim 1 wherein both twist grippers (11a, lib) are rotatably driven in the same angular direction.

3. The machine of claim 2 wherein both wire twist grippers are driven by the same motor (12) .

4. The machine of anyone of the preceding claims wherein the wire twist grippers (11a, lib) are arranged adjacent each other in proximity, facing in substantially identical directions.

5. The machine of anyone of the preceding claims wherein the cable mid-section support (14) is moveable in an axial direction (A) for tensioning the cable during twisting thereof.

6. The machine of the preceding claim wherein the axial direction (A) is parallel to the axis of rotation of the wire twist gripper (11a, lib) .

7. The machine of anyone of the preceding claims wherein the wire conductors (5) extend against or closely adjacent a base (17) for reducing vibrations of the cable during twisting.

8. The machine of the preceding claim wherein the base section is curved thereby partially surrounding the cable therein.

9. A method of preparing twisted cables with a machine, each cable comprising at least two wire conductors (5) , comprising the steps of: providing at least two wires (5) of similar length; gripping opposed ends of the two wires with respective grippers (11a, lib) of the machine such that the wire ends are in proximity of each other and the wires are arranged in a U-shaped loop (16); rotating at least one of the grippers (11a, lib) such that said at least two wires (5) twist about each other.

10. The method of claim 9 wherein both grippers (11a, lib) are rotated during the twisting operation.

11. The method of claim 9 or 10 wherein during the twisting of the wire conductors, the U-shaped loop (16) is supported by a mid-section support (14) of the machine, the mid-section support tensioning the wire loop away from the grippers (11a, lib) .

12. The method of any one of claims 9-11 wherein the machine according to any one of claims 1-8 is provided for twisting the conductors.