GB2193124A - Machine for preparing wiring conductors - Google Patents

Abstract

The machine has a bed (1) supporting a drive (2) operatively connected to a mechanism (3) for measuring and cutting the conductor, a mechanism (5) for placing conductor lengths (4) into devices (6) for clamping them which are disposed on a stepping conveyor (7) which transfers the conductor lengths to devices (22, 23) for preparing the ends of the conductors installed along the conveyor (7) in a processing sequence, and a mechanism (8) for removing the prepared conductor lengths from the conveyor having a guide member (24) mounted on the bed (1), a carriage (27) moving in parallel with the guide member (24), a lever (31) mounted on the carriage (27) and having a clamping member (81) which transfers the looped conductor lengths (4) to between combs (53, 54) mounted with their teeth facing one another for vertical reciprocations in a groove (25) of the guide member (24) and on the carriage (27), respectively. The combs, by longitudinal movement of the top comb (53) transfer the lengths (4) to an end of the guide member (24) for eventual stacking. <IMAGE>

Description

SPECIFICATION Machine for preparing wiring conductors The invention relates to the production equipment for preparing wiring conductors, and in particular, to a machine for preparing wiring conductors, and it may be used in the electrical engineering, as well as in the radio and instrumentation engineering.

The machine is designed for cutting screened or unscreened wiring conductors into pre-set lengths and for subsequent preparation of the conductor ends. Such preparation may include unbraiding and twisting metal filaments of shielding braid stripping insulation at the conductor ends, twisting bare ends of a multiple-strand conductor and tinning the bare ends of the conductor and twisted filaments of the shielding braid.

Various lengths of wiring conductors are used in the manufacture of electrical equipment. Wiring conductors length may largely vary. Most frequently the use is made of conductor lengths from 100 to 1000 mm.

Since the demand for wiring conductors cut into pre-set lengths and appropriately prepared is very high in industry, a great attention is paid to the problems associated with the development of machines for preparing wiring conductors.

Thus, known in the art is a machine for preparing wiring conductors, comprising a bed supporting a drive operatively connected to a mechanism for measuring and cutting a conductor, a mechanism for placing conductor lengths into devices for their clamping which are disposed on a stepping conveyoer which transfers the conductor lengths to devices for preparing the conductor ends installed along the conveyor in a sequence of processing, and a mechanism for removing the prepared conductors from the conveyor.

The mechanism for measuring and cutting wiring conductors is designed for preparing pre-set lengths of a wiring conductor. For moving a conductor length along a production line for preparing the conductor ends, the use is made of a stepping conveyor having devices for clamping conductor lengths. The ends of a conductor length are retained in each clamping device. The stepping conveyor is mounted in such a manner that one of the devices for clamping a conductor length is always positioned opposite a guide member of the mechanism for measuring and cutting the conductor after the conveyor has moved one step further.The mechanism for placing the conductor length into a device for clamping comprises a hook mounted for reciprocations in the direction at right angles to the direction of movement of the stepping conveyor and engages, in one extreme position, the guide of the mechanism for measuring and cutting the conductor. The mechanism for removing conductor lengths from the conveyor in a pilot machine for cutting wiring conductors according to the above cited patent specification comprises a hook similar to that used in the mechanism for placing conductor lengths into the device for clamping conductor lengths, mounted for reciprocations in the direction at right angles to the direction of movement of the stepping conveyor and engaging, when in one extreme position, the device for clamping conductor lengths at the end of the production cycle of preparation of a conductor length.

The mechanism for measuring and cutting conductors, the mechanism for placing conductor lengths into devices for clamping them, the mechanism for removing conductor lengths from the conveyor and the stepping conveyor are operatively connected to the drive by means of a system of levers and a cam mechanism.

The mechanism for removing conductor lengths from the conveyor pulls conductor lengths out of the device for clamping them, and the conductor lengths fall freely into a container "in bulk". When a large quantity of prepared conductor lengths are piled-up in the container, they engage one another at the ends so that they are deformed and should be manually separated and straightened. Therefore, the machine for preparing wiring conductors does not allow the prepared conductors to be obtained without deformations, which is especially so in preparing conductors of a large length.

It is an object of the invention to provide a machine for preparing wiring conductors having a mechanism for removing conductor lengths from the conveyor which would make it possible to eliminate deformation of the prepared ends of conductor lengths when they are removed from the conveyor.

This accompiished by that in a machine for preparing wiring conductors, comprising a bed supporting a drive operatively connected to a mechanism for measuring and cutting the conductor, a mechanism for placing conductor lengths into devices for clamping them which are disposed on a stepping conveyor which transfers the conductor lengths to devices for preparing the ends of the conductors installed along the conveyor in the production processing sequence, and a mechanism for removing the prepared conductor lengths from the conveyor, according to the invention, the mechanism for removing the conductor lengths from the conveyor comprises a guide member mounted on the bed to extend at right angles to the direction of movement of the stepping conveyor, a carriage operatively connected to the drive and mounted on the bed for reciprocations in parallel with the guide member which has a longitudinal groove in which a lower comb is mounted for vertical reciprocations, the lower comb being operatively con nected to the drive, an upper comb mounted on the carriage for vertical reciprocations, a lever mounted on the carriage and having a free end supporting a clamping member which in one extreme position of the carriage is disposed above the device for clamping conductor lengths and which engages the guide member when the carriage is moved to the other extreme position, the clamping member being operatively connected to the lower comb in such a manner that it extends under the guide member during the return stroke of the carriage, and the lower comb has the end face of at least one tooth engaging the end face of a respective tooth of the upper comb, the end faces of the teeth of the combs being disposed under the guide member at a distance therefrom which is greater than the conductor diameter.

It is preferred that in the machine according to the invention the clamping member be made in the form of a rod having, at the free end thereof on the side opposite the device for clamping conductor lengths, a wedgeshaped projection having one of the facets thereof facing towards the guide member, and three wedge-shaped projections be provided on the end face of the rod facing towards the guide member, the middle projection being received in the groove of the guide member when the carriage moves towards the other extreme position Therefore, the structural arrangement of the mechanism for removing the conductor lengths from the conveyor according to the invention makes it possible to eliminate deformation of prepared ends of the conductor lengths when they are removed from the conveyor and ensures the formation of a package of prepared conductors.

The invention will now be. described with reference to the accompanying drawings which show: Figure 1 is a general perspective view of a machine for preparing wiring conductors with a bed partially in section showin a part of a table of a mechanism for measuring and cutting the conductor according to the invention; Figure 2 is an enlarged view taken along arrow A in Fig. 1 showing relative position of a part of-a guide member, clamping member, upper and lower combs in the position after a conductor length has been released during the return stroke of the carriage according to the invention; Figure 3 is an enlarged view taken along arrow A in Fig. 1 showing relative position of a part of a guide member and clamping member in the position before the conductor length is released according to the invention; Figure 4 is a vaiew taken along arrow B in Fig. 3 according to the invention;; Figure 5 shows an enlarged view of a device for clamping conductor lengths with a partial view of a pallet of the conveyor and clamping member disposed thereabove in one of the extreme positions; according to the invention.

A machine for preparing wiring conductors comprises a bed 1 (Fig. 1) which supports a drive 2 operatively connected to a mechanism 3 for measuring and cutting the conductor into lengths 4, a mechanism 5 for placing conductor lengths into devices 6 for clamping them which are disposed on a stepping conveyor 7, and a mechanism 8 for removing conductor lengths from the stepping conveyor 7.

The stepping conveyor 7 is designed for transferring conductor lengths 4 along the production line for their preparation. The conveyor has two guide troughs 9,10 installed one above the other and pallets 11 mounted for movement along the troughs 9,10 and each supporting a device 6 for clamping conductor lengths 4.

Pushers 12, 13 operatively connected to the drive 2 (in the manner not shown) are provided for moving the pallets 11 along the troughs 9,10 so as to provide for movement of the pallets 11 through one step equal to the length of the pallet 11. For the transfer of the pallets 11 from the upper trough 9 into the lower trough 10, and vice versa, cross members 14 and 15 are mounted adjacent to the troughs, respectively, for rotation, which are operatively connected to the drive 2 (not shown in the drawing). Each pallet 11 has a T-slot 16 and the free ends of the cross members 14 and 15 have the corresponding T-shaped configuration.

The mechanism 3 for measuring and cutting the conductor is similar to that described in French patent No. 8021461. It comprises a table 18 (only a part of the table is shown in the drawing) mounted on a plate 19 which is rigidly secured, e.g. by welding, to the bed 1.

The mechanism 5 for placing conductor lengths into the devices 6 for clamping them comprises a pusher 20 mounted on the bed 1 for vertical reciprocations, and a hook 21 mounted for reciprocations in the direction at right angles to the direction of movement of the conveyor 7. The pusher 20 is disposed between the table 8 and stepping conveyor 7, and the hook 21 is disposed opposite to the pusher 20 on the other side of the stepping conveyor 7.

The production line for preparing the ends of the wiring conductor lengths 4 includes various devices such as a device for twisting unbraided filaments of the shielding braid, a device for burning insulation, a device for stripping insulation and imparting additional twist to the conductor strands, a flux applicator and a device for tinning the conductor ends, which are mounted on the bed 1. The drawing shows a device 22 for unbraiding the shielding braid at the ends of the conductor and a device 23 for separating the filaments of the shielding braid from the stripped end of the conductor only. All similar devices may be of any appropriate known type, e.g. of the type disclosed in the abovecited French patent specification.

The mechanism 8 for removing the prepared conductors ends from the conveyor 7 comprises a guide member 24 extending at right angles to the direction of movement of the conveyor 7, one end of the guide member being disposed adjacent to the trough 9 and secured to the bed 1, e.g. by means of a threaded joint. A longitudinal groove 25 extends along the whole extent of the guide member 24, and an arm 26 is secured to the free end of the guide member 24.

The mechanism 8 also comprises a carriage 27 operatively connected to the drive 2 and mounted on the bed 1 for reciprocations in parallel with the guide member 24. For that purpose, the bed 1 has a guide slot 28, and the carriage 27 has a shaft 29 with rollers 30 which are received in the slot 28.

The carriage 27 also carries a lever 31 having one end thereof pivotally connected, by means of a pivot pin 32, to one end of a double-arm lever 33 having the other end thereof pivotally connected by means of a pivot pin 34, to the end of a pull rod 35. The other end of the pull rod 35 is secured to the carriage 27 by means of a pivot pin 36. A slide 37 is mounted on the carriage 27 for reciprocations. For that purpose, the carriage has a guide slot 38, and the slide 37 has a pin 39 carrying a roller 40 received in the slot 38. The length of the slot 38 determines the amount of travel of the slide 37. In addition, the slide 37 is connected, by means of a pivot pin 41, to a pull rod 42 which is connected to a pivot pin 43 of the double-arm lever 33. The slide 37 has a through hole 44 in which the lever 33 is received for reciprocations along the hole 44.One end of a tension spring 45 is secured to the slide 37 and the other end of the spring is rigidly secured to the carriage 27. The carriage 27 has a pivot pin 46 for supporting a lever 47 having one end thereof engaging the pin 39 and the other end carrying a pin with a roller 49 engaging a cam 50 rigidly secured to the bed 1 by means of a bracket 51. The cam 50 has a cam portion 52.

The mechanism 8 for removing conductor lengths from the conveyor also comprises upper and lower combs 53 and 54 having their teeth facing towards one another. The upper comb 53 is mounted on the carriage 27 for vertical reciprocations. For that purpose, the carriage 27 has two pins 55, and two ligs 56 with holes 57 are respectively provided at the ends of the comb 53, the pins 55 being received in the holes. The lower comb 54 is received in the groove 25 of the guide member 24 and is mounted for vertical reciprocations. For these reciprocations to be effected, the lower comb 54 has pins 58 carrying rollers 59, and a pair of guide holes 60 receiving the rollers 59 are provided in the lateral side of the guide member 24.

The holes 57 and 60 are elongated to extend in the directions of movement of the upper and lower combs 53 and 54, respectively.

The length of the holes 57 and 60 determines the desired amount of travel of the combs 53 and 54.

The lower comb 54 is operatively connected to the drive 2.

The drive 2 has a motor 61 which is connected, by means of a belt transmission 62, with a shaft 63 mounted on the bed 1. A crank 64 carrying a cam 65 is mounted on the shaft 63.

The crank 64 connected, by means of a pin 66, to one end of a pitman 67 having the other end thereof connected by means. of a pin 68 to a lever 69, the pin being mounted in the intermediate portion of the lever 69.

One end of the lever 69 is connected, by means of a pivot pin 70, to the bed 1, and the other end is made in the form of a fork 71 which engages a pin 72 rigidly secured to the carriage 27.

The drive 2 also comprises a double-arm lever 73 which is secured to the bed 1 by means of a pivot pin 74, one arm 75 of the double-arm lever engaging the lower comb 54.

For that purpose, the lower comb 54 has a projection 76 received in a hole 77 of the guide member 24. The end of the other arm 78 of the lever 73 carries a pin 79 with a roller 80 engaging the pitman 64.

The free end of the lever 31 carries a clamping member 81 operatively connected to the drive 2.

The operative connection is effected through a roller 82 secured by means of a pin 83 to the slide 37. The roller 82 engages a rail 84 extending in parallel with the guide member 24 and mounted on the bed 1 for vertical reciprocations. One end of the rail 84 is connected by means of a pin 85 to a lever 86 which is secured to the bed 1 by means of a pivot pin 87. The other end of the rail 84 carries a pin 88 to which is secured one end of a pull rod 89 having the other end thereof rigidly secured, e.g. by welding, to the arm 78 of the lever 73.

Teeth 90 (Fig. 2) and 91 of the upper and lower combs 53 and 54, respectively, should be spaced from one another at a distance such that the conductor length 4 could be received freely therebetween, i.e. the distance should be greater than the conductor diameter. The ratio of spacings of the teeth 90 and 91 of the upper and lower combs 53 and 54 may be of any value, but there should be no meshing of the teeth 90 and 91, i.e. during engagement of the combs 53 and 54, the lower comb 54 should engage with the end face of at least one tooth 91 the end face of a respective tooth 90 of the upper comb 53.

During the return stroke of the carriage 27 (the direction of movement is shown by arrow), the lower comb 54 protrudes from the groove 25, and the end faces of the teeth 90 and 91 of the combs 53 and 54 are disposed above the guide member 24 at a distance "a" which is greater than the diameter of the conductor. The clamping member 81 is disposed above the guide member 24 in this position.

The clamping member 81 comprises a rod 92 (Figs. 2,3,4,5) having one end secured to the lever 31 and the free end which is enlarged and has a wedge-shaped projection 93.

A spring 94 is disposed between the projection 93 and lever 31 for urging the conductor length 4 against the guide member 24 with a force that prevents the conductor from slipping. The projection 93 (Fig. 3) is disposed on the side opposite to the device 6 for clamping the conductor lengths 4, and one of the facets thereof faces towards the guide member 24 and defines an acute angle ce with respect thereto. The projection 93 provides for a guided movement of a portion of bent of the conductor length 4 towards the space under the end face of the rod 93 before pulling the conductor length 4 out of the device for clamping the conductor.

When the carriage 27 is moved to the other extreme position, the clamping member 81 (Figs. 3,4) engages the guide member 24, and the lower comb 54 is fully received in the groove 25 of the guide member 24. Three wedge-shaped projections 95, 96, 97 (Fig. 4) are provided in the end face of the rod 92 facing towards the guide member 24. The middle projection 96 is received in the groove 25 of the guide member 24, and the projections 95 and 97 are disposed outside, on either side of the guide member, when the carriage 27 moves away from the device 6 for clamping conductor lengths to the other extreme position. In this extreme position, the projection 96 also engages the bent portion of the conductor length 4 and forces it into the longitudinal groove 25, while branches of the conductor length 4 are disposed outside the projections 95 and 97 in parallel with the guide member 24 (Fig. 3).The ends of the conductor length 4 are retained in the clamping device 6 mounted on the pallet 11 of the conveyor 7. The clamping device 6 comprises two brackets 98 (Fig. 5) and a bar 99 mounted therebetween for reciprocations and engaging a spring 100 having the other end thereof bearing against the pallet 11. The clamping member in Fig. 5 is shown in the extreme position above the clamping device 6.

The machine for preparing wiring conductors functions in the following manner. The conductor length-4 (Fig. 1) is taken from the table 18 of the mechanism 3 for measuring and cutting the conductor and is drawn by means of the hook 21 and pusher 20 of the mechanism 5 for placing conductor lengths into the devices 6 for their clamping between the brackets 98 (Fig. 5) of the clamping device 6, the bar 99 urging the ends of the conductor length 4 against the brackets 98.The pusher 12 (Fig. 1) cooperating with the last pallet causes all pallets 11 to move through one step in the trough 9 of the conveyor 7 along the production line of preparation of the wiring conductors in which the ends of the conductor length 4 are prepared in the device 22 for unbraiding the shielding at the ends of the conductor and in the device 23 for separating the unbraided filaments of the shielding traid from the stripped conductor end. At the end of the trough 9, the last pallet 11 moves so that its slot 16 is put onto the free end 17 of the cross member 14. The cross member 14 is rotated to transfer the pallet 11 from the upper trough 9 to the lower trough 10. The pusher 13 moves the pallets 11 along the trough 10 towards the devices 22, 23 for further treatment of the ends of the conductor length 4.When the pallet 11 is in the extreme position in the trough 10, its groove 16 is put onto the free end of the cross member 15, and the cross-member is rotated to transfer the pallet 11 containing the prepared ends of the conductor length from the lower trough 10 to the upper trough 9 to be positioned opposite to the guide member 24 of the mechanism 8 for removing conductor lengths from the conveyor 7. A U-shaped loop of the conductor 4 rests freely on the guide member 24 or hangs laterally therefrom depending on the conductor length.Initially the carriage 27 and slide 37 are in the extreme righthand position, the roller 49 engages the cam portion 52 of the cam 50, the clamping member 81 (Fig. 5) is above the device 6 for clamping conductor lengths, and the lower comb 54 (Fig. 1) is within the groove 25 in the extreme position so that the end faces of its teeth 91 (Fig. 4) do not protrude from the groove 25 of the guide member 24.

When the drive 2 is energized, the shaft 63 starts rotating in the direction indicated by arrow to rotate the crank 64 and cam 65. The pitman 67 will push the lever 69 to the right so that the lever will turn to push, with the fork 71, the pin 72 thus causing the carriage 27 to move to the left. The roller 49 moves to the left along the cam 50, the lever 47 engages the pin 39 also to push the slide 37 to the left relative to the carriage 27 until the roller 40 is in the extreme lefthand position in the slot 38. Now the lever 33, pull rods 42 and 35 will interact to move the lever 31 along the hole 44 of the slide 37 to the extreme lefthand position with respect to the carriage 27 and slide 37.

Therefore, the slide 37 and lever 31 will be in the fixed extreme lefthand position with respect to the carriage 27. At the moment the lever 31 starts moving to the left, the clamping member 81 starts sliding along the guide member 24. The projection 96 (Fig. 4) will enter the groove 25 of the guide member 24.

The loop of the conductor length 4 (Fig. 1) will be on either side of the clamping member 81 to extend freely therearound at this stage.

During the movement of the carriage 27 to the left, the clamping member 81 (Fig. 3) moves along the guide member 24 to tighten the loop of the conductor length 4, gradually placing it in the position along the guide member 24. When the wedge-shaped projection 93 engages the bent portion of the conductor length 4, the conductor is tightened and, as the clamping member 81 continues to move to the left, the bent portion of the conductor length 4 engages the facet of the wedgeshaped projection 93 facing towards the guide member 24 to slide thereover and to get under the end face of the rod 92. As a result of engagement of the bent portion of the conductor length 4 with the wedge-shaped projections 95, 96 and 97 (Fig. 4) of the end face of the rod 92, the conductor length 4 is deformed at its bent portion and is forced by the projection 96 into the groove 25 of the guide member 24.The branches of the conductor length 4 rest on top of the projections 95, 97 outside the clamping member 81 to extend along the guide member 24. Therefore, the bent portion of the conductor length 4 is clamped between the projection 96 and the guide member 24. Now, as the carriage 27 continues to move to the left (Fig. 1) with the slide 37 and lever 31, the conductor length 4, which is reliably clamped at the bent portion between the projection 96 and the guide member 24 (Fig. 4), will be pulled out from the space between the brackets 98 and bar 99 (Fig. 5).

Meanwhile, as the shaft 63 rotates (Fig. 1), the roller 80 starts cooperating with the cam 65. The lever 73 will turn so that the arm 75 will push the projection 76 of the lower comb 54, and the pull rod 89 will push the rail 84 up. The lower comb 54 will start moving to the left and upwards and will ieave the groove 25.

At the same time, the pull rod 89 will push the pin 88 up, and the rail 84 will turn about the pivot pin 87. The rail 84 will rise and will push the roller 82 and slide 37 up. As a result, and also owing to the cooperation of the pin 39 with roller 40 with the slot 38, the slide 37 will turn with respect to the carriage 27 and will raise the clamping member 81 (Fig. 2) above the guide member 24 so as to release the conductor length 4 clamped at the bent portion. At the same time, the comb 54 moves upwards from the groove 25 to take the conductor length 4, which now hangs between the teeth 90 of the comb 54, and the ends of the conductor length released out from the clearance between the brackets 98 and bar 99 (Fig. 5) will freely hang down.

During its upwards movement, the comb 54 (Fig. 2) will engage with its teeth 91, without meshing, the teeth 90 of the upper comb 53 freely hanging from the pins 55 and will raise it. Now the lower comb 54 is covered by the upper comb 53 on top of it, and the clamping member 81 is under the guide member 24.

This position corresponds to the extreme lefthand position of the carriage 27 (Fig. 1) which it occupies as the shaft 63 rotates.

Subsequently, owing to the cooperation of the crank 64, pitman 67, lever 69, fork 71 and pin 72, the carriage 27 starts moving to the right. The slide 37, the lever 31 with the clamping member 81 and the upper comb 53 will start moving together with the carriage 27, the roller 49 will ride over the cam 50.

When the crank 64 is in the righthand dead center position, the carriage 27 is in the initial extreme righthand position, The roller 49 engages the cam surface 52 of the cam 50 so that the lever 47 turns about its pivot pin 46, and the free end thereof moves away from the pin 39. The slide 37 moves under the action of the spring 45 to the right. Cooperation of the lever 33, pull rod 42 and pull rod 35 results in the slide 37 being rotated about the pin 39, and the lever 31 moves along the hole 44 to the right with respect to the slide 37. As a result, the clamping member 81 takes the initial position above the device 6 for clamping the conductor. The lower comb 54 is lowered into the groove 25 of the guide member 24, hence the upper comb 53 is also lowered. The conductor length 4 is left hanging from the guide member 24.

Therefore, the bent portion of the conductor length 4 is left between the teeth 90 of the upper comb 53 (Fig. 2) so that it cannot fall down. Subsequently, as the shaft 63 continues to rotate (Fig. 1), cooperation of the crank 64, pitman 67, lever 69, fork 71 and pin 72 results in the carriage 27 moving to the left again. The upper comb 53 is also caused to move to the left so that its teeth 90 (Fig. 2) slide over the guide member 24 thereby causing the conductor length 4 to move to the left along the guide member 24 through a distance equal to the amount of stroke of the carriage 27 (Fig. 1) until the conductor length 4 slips down onto the arm 26 where the conductor lengths 4 are stacked to form a package.

Claims (3)

1. A machine for preparing wiring conductors, comprising a bed supporting a drive operatively connected to a mechanism for measuring and cutting the conductor; a mechanism for placing conductor lengths into devices for clamping them which are disposed on a stepping conveyor which transfers the conductor lengths to devices for preparing the ends of the conductors installed along the conveyor in a processing sequence, and a mechanism for removing the prepared conductor lengths from the conveyor comprising a guide member mounted on the bed to extend at right angles to the direction of movement of the stepping conveyor, a carriage operatively connected to the drive and mounted on the bed for reciprocations in parallel with the guide member which has a longitudinal groove in which is mounted a lower comb 54 for vertical reciprocations, the lower comb being operatively connected to the drive, an upper comb mounted on the carriage for vertical reciprocations, a lever mounted on the carriage and having a free end supporting a clamping member which in one extreme position of the carriage is disposed above the device for clamping conductor lengths and which engages the guide member when the carriage is moved to the other extreme position, the clamping member being operatively connected to the lower comb in such a manner that it extends under the guide member during the return stroke of the carriage, and the lower comb has the end face of at least one tooth engaging the end face of a respective tooth of the upper comb, the end faces of the teeth of the combs being disposed under the guide member at a distance therefrom which is greater then the conductor diameter.

2. A machine for preparing wiring conductors according to claim 1, in which the clamping member is made in the form of a rod having, at the free end thereof on the side opposite to the device for clamping conductor lengths, a wedge-shaped projection having one of the facets thereof facing towards the guide member, and in that three wedgeshaped projections are provided on the end face of the rod facing towards the guide member, the middle projection being received in the groove of the guide member when the carriage moves towards the other extreme position.

3. A machine for preparing wiring conductors substantially as hereinabove described with reference to, and as shown in the accompanying drawings.