GB1599889A - Wire-wrap bit for making wrappedwire connections to terminal tags - Google Patents

Description

(54) A WIRE-WRAP BIT FOR MAKING WRAPPED-WIRE CONNECTIONS TO TERMINAL TAGS (71) We, THE PLESSEY COMPANY LIMITED of Vicarage Lane, Ilford, Essex IG1 4AQ and D. T. & G. (DESIGNS, TOOLS & GAUGES) LIMITED, of 92 London Road, Liverpool L3 5NW, both British Companies do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : - The present invention relates to a wirewrapping bit for use in making wrapped-wire connections to terminal-tags and is particularly concerned with that kind of bit which, in one continuous process, cuts an end of a plastics-coated wire to a predetermined length, removes the plastics coating from the end region of the wire and wraps that end region tautly around a terminal-tag as a series of side-by-side convolutions.

The invention is applicable to those wirewrapping devices which are held in one hand after the manner of a pistol and are driven from a power source, e.g. electrical or pneumatic, under the control of a fingeroperated trigger. However the invention is not necessarily limited to devices of this particular form.

Wire-wrapping devices of the above kind are finding increasing use for instance in the telephone equipment industry where vast numbers of single-core wires, covered with polyvinyl chloride (p.v.c.), are required to be connected to terminal-tags protruding from multi-point tag blocks or the like. Using tags of elongated form and rectangular cross section, a known type of wire-wrapping device is capable of the high-speed production of highly-reliable and neat solderless connections, each in the form of a predetermined number (preferably six) of taut side-by-side convolutions. Indeed the device may be used in producing a succession of wrapped connections along the length of a tag starting at or towards its base.

The known form of wire-wrapping device, comprises a so-called gun for providing the motive power and a so-called bit which is concerned with manipulation of the wires in the formation of the connections. The gun, provided with a hand-grip and triggeroperated switch, has a rotatable shaft within its barrel region; the shaft being driven by a small electric motor, incorporated in the gun, under control of the trigger-operated switch. A collet-type chuck which is not rotatable by said shaft is provided at the end of the barrel portion of the gun for the securement of the outwardly extending bit co-axially with respect to the rotatable shaft. The bit generally comprises concentric sleeve and spindle portions of tool steel which are rotatable with respect to each other, and is about 3 in. long. One end of the spindle, which may be conveniently termed the nose end, co-operates with the terminal and the wire to be connected thereto whereas the other end (or heel end) of the spindle has a small portion emerging from the sleeve.

This emergent end of the spindle is arranged to "key" in one angular position with the end of the beforementioned rotatable shaft within the barrel of the gun. Moreover that end of the bit-sleeve which is inserted in the barrel-chuck is "keyed" in a particular angular position with respect to fixed jaws of the chuck, and when the chuck is tightened the sleeve is held stationary with respect to the body of the gun, whereas the spindle is coupled to, and in effect is an extension of, the gun shaft.

It should be mentioned that, in the known form of wrapping device, when the motor is de-energised the rotatable shaft and therefore the bit-spindle is caused to come to rest in a particular angular position; an arrangement, for example incorporating a permanent magnet, being provided within the gun for this purpose.

The bit envisaged by the present invention is of the kind in which the nose-end of the spindle terminates just within the free end of the sleeve, and that end of the spindle has a substantially central hole to a depth which is sufficient to accommodate the length of the terminal-tag to be served; the diarneter of the hole being sufficient to enable the spindle to be rotated freely around the tag without excess lateral play. The face at the nose-end of the spindle has a suitable protrusion for duly forming a stripped wireend smoothly and tautly around a terminaltag. The general form of the bit, has a channel formed in the spindle; the channel extending lengthwise from the nose-end and being dimensioned so as to readily accommodate the diameter of the plastics-covered wire. Also in the general form of the bit, the length and configuration of the channel is such that an end of a plastics-covered wire inserted from the nose end is guided by the groove through a cut-out in the wall of the sleeve. The cut-out and the channel duly co-operate when the spindle is rotated, within the stationary sleeve, to cropp-off that portion of insulated wire which is in excess of requirements. This leaves sufficient within the bit to provide a good wrapped connection of say six convolutions; the bit being provided with internal means for stripping the insulation from the end-region within the bit as rotation of the spindle proceeds to perform the wrapping function.

It is an aim of the present invention to provide a wire-wrapping bit which is simple and efficient and of increased reliability.

According to the invention there is provided a wire-wrapping bit comprising a sleeve and a spindle, the spindle being accommodated within the sleeve and rotatable with respect thereto and having at one end of a front face incorporating a protrusion adapted in operation to form a stripped wire end around a terminal tag to be wrapped, which terminal tag is located in a recess in the said one end of the spindle and enveloped by the free end of the sleeve and the spindle also includes a channel which extends lengthwise from the one end and is adapted to accommodate plastics-covered wire inserted into the free end of the sleeve and guided by the channel in the spindle through a wire cropping cut-out in the wall of the sleeve, in which the lengthwise channel of the spindle includes an insulation-piercing means and the free end of the sleeve of the bit is opened out to form a hood which is of gradually diminishing height and width towards its inner end which forms a pocket in conjunction with the spindle and is arranged such that when the end of the plastics-covered wire is fed into the pocket the wire is guided along the channel from a point remote from the end face and beyond said insulation-piercing means, the pocket also serving, when the spindle is rotated within the sleeve, to urge the covered wire into co-operation with the insulation-piercing means to effect piercing and gripping of the wire-covering preparatory to sripping off the covering from the end portion of the wire.

The invention will be better understood from the following description of the preferred method of carrying it into effect which should be read in conjunction with the drawing accompanying the provisional specification drawing comprising Figs. 1, la, 2, 3 and 4.

Of the drawing Fig. 1 and 2 represent the spindle and sleeve portions respectively of the proposed wire-wrapping bit; Fig. la is an enlarged side view of the nose-end of the spindle; Fig. 3 is a cross-sectional representation of the nose-end portion of the assembled spindle and sleeve; whereas Fig. 4 shows a portion of plastics-covered wire and the effect of the bit as regards piercing the covering preparatory to stripping-off the end portion.

Referring to Fig. 1 the spindle 10, typically of tool-steel, comprises concentric portions 14a and 14b (of which the first is slightly smaller in diameter) and an enlarged heel-end portion 12 providing the shoulder 12a Portion 12 is provided with a so-called "flat" 13 which serves to orient the spindle in a specific manner with respect to the drive shaft of the wrapping gun when the bit is located in the collet-chuck incorporated in the barrel portion of the gun. Portion 14a has a lengthwise channel 15 produced for instance by endmilling. This channel has opposing insulationpiercing blades formed in its side-walls a short distance from the nose-end of the spindle, the distance serving to determine the amount of covered wire which is to be included in the wrap at the bottom of the wrapped connection. In general the channel is dimensioned to freely accommodate the overall diameter of the covered wire, the exceptions being the waist region formed by said blades, and also the right-hand end of the channel which is chamfered to meet the circumferential surface of spindle portion 14a.

A central hole 16 is formed in the noseend of the spindle and this is of sufficient depth to accommodate the length of the terminal-tag to be wrapped and is of such diameter as to allow the spindle to be freely rotated about the tag. The end of the spindle also includes a known form of pad or protrusion 17 which is effective in smoothly forming the wire around the terminal-tag.

The enlarged representation Fig. la of the end portion of the spindle, viewed from above the channel 15, again shows the wireforming pad 17. It also shows the opposed blades 18 and 19 emerging from the channelwalls, which are to perform piercing and gripping functions on the plastics covering of the wire. In the example, the blades are produced when the channel is being endmilled, and it is to be noted that the central gap between the blades is slightly greater than the diameter of the wire-core so that scarring or nicking of the wire is avoided.

The sleeve 11 shown in Fig. 2 is also of tool-steel and comprises a tube having two internal diameters corresponding to parts 14a and 14b of the spindle The spindle when fitted snugly into the sleeve, with the shoulder 12s abutting the right-hand end of the sleeve, is free to rotate with barely perceptible sideplay. With the two parts so fitted together, the pad 17 is just below the left-hand end of the sleeve.

The sleeve is provided at its right-hand end with a key way (not shown) which is arranged to co-operate with the collet-chuck of the gun to ensure proper orientation of the sleeve. The width of the nose-end of the sleeve is reduced by the machining of diametrically opposite flat-faces such as 22.

A cut-out 23 is machined in the sleeve and a cropping blade 24 is formed in this region and is duly to co-operate with one edge of the beforementioned channel 15 to cropoff that end of the covered wire which emerges through the cut-out.

At the left-hand end of the sleeve the interior 20 is not circular but is opened out at region 21 over an area to form a hood. The opening out extends over an area to a depth taking it beyond the position to be occupied by the channel blades 18 and 19 of the spindle. The pocket formed when the spindle is fitted, lies substantially evenly about said channel when the bit is secured by the gun. Moreovcr the pocket region gradually diminishes in height and width towards the inward end.

Referring to Fig. 3 illustrating the noseend of the bit, when the two components have been oriented upon securement by the barrel of the gun. Therefore the channel 15 is embraced by the pocket region 21 of the sleeve, and moveover the end of the channel Is exposed at the side of croppingblade 24. Accordingly a plastics-covered wire which is to be subjected cutting, stripping and wrapping may be readily directed into the pocket and made to follow the dotted path WP. In this regard, the wire passes above and clear of the piercing blades 18 and 19, and at the root of the pocket is constrained to follow the channel, and then, following the chamfered end of the channel the coveredwire emerges, through cut-out 23, to lie alongside the cropping blade 24.

The hole 16 at the nose-end of the bit is duly placed over the terminal-tag to be wrapped, the emergent end of the covered wire is pulled through the cut-out as necessary to take-up the slack, whereupon the gun is started to drive the spindle in the direction of the arrow (Fig. 1). The initial movement causes the excess wire to be cropped-off by the shearing action blade 24 and an edge of channel 15. As rotation proceeds the action of the pocket region is to urge the portion of covered wire which is to the left of point A, (Fig. 3) into the channel. Therefore blades 18 and 19 engage the plastics covering to grip and pierce the insulation 27 at points 28 and 29 as shown in Fig. 4, the wirecore 26 remaining untouched by the blades.

As further rotation of the spindle takes place the pad 17 (Fig. 1) forms the wire around the terminal tag. During the wrapping action the wire stripped beyond the piercing blade is drawing out of the bit.

In practice it is found that the tubular portion of plastics material which is stripped frond the wire is readily ejected from the bit when another wire-end is inserted preparatory to another joint being made.

Instead of forming the piercing blades 18 and 19 during the milling of the channel, they may be incorporated in a small preferably detachable U-shape unit located in a lateral slot which would then be provided in the spindle.

Further the tag co-operating end section of the spindle 10 may be made removable so that the bit can accommodate differing sized lengthwise channels 15, for a range of wire diameters, and differing sized central holes 16, for a range of terminal sizes.

WHAT WE CLAIM IS: 1. A wire wrapping bit comprising a sleeve and a spindle, the spindle being accommodated within the sleeve and rotatable with respect thereto and having at one end a front-face incorporating a protrusion adapted in operation to form a stripped wire end around a terminal tag to be wrapped, which terminal tag is located in a recess in the said one end of the spindle and enveloped by the free end of the sleeve and the spindle also includes a channel which extends lengthwise from the one end and is adapted to accommodate plastics covered wire inserted into the free end of the sleeve and guided by the channel in the spindle through a wire cropping cut-out in the wall of the sleeve, in which the lengthwise channel in the spindle includes an insulation-piercing means and the free end of the sleeve of the bit is opened out to form a hood, which is of gradually diminishing height and width towards its inner end which forms a pocket in conjunction with the spindle and is arranged such that when the end of the plastics-covered wire is fed into the pocket the wire is guided along the channel from a point remote from the end face and beyond the insulationpiercing means; the pocket also serving, when the spindle is rotated within the sleeve, to urge the covered wire into co-operation with the insulation-piercing means to effect piercing and gripping of the wire covering preparatory to stripping off the covering from the end portion of the wire.

2. A wire wrapping bit according to claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. The sleeve 11 shown in Fig. 2 is also of tool-steel and comprises a tube having two internal diameters corresponding to parts 14a and 14b of the spindle The spindle when fitted snugly into the sleeve, with the shoulder 12s abutting the right-hand end of the sleeve, is free to rotate with barely perceptible sideplay. With the two parts so fitted together, the pad 17 is just below the left-hand end of the sleeve. The sleeve is provided at its right-hand end with a key way (not shown) which is arranged to co-operate with the collet-chuck of the gun to ensure proper orientation of the sleeve. The width of the nose-end of the sleeve is reduced by the machining of diametrically opposite flat-faces such as 22. A cut-out 23 is machined in the sleeve and a cropping blade 24 is formed in this region and is duly to co-operate with one edge of the beforementioned channel 15 to cropoff that end of the covered wire which emerges through the cut-out. At the left-hand end of the sleeve the interior 20 is not circular but is opened out at region 21 over an area to form a hood. The opening out extends over an area to a depth taking it beyond the position to be occupied by the channel blades 18 and 19 of the spindle. The pocket formed when the spindle is fitted, lies substantially evenly about said channel when the bit is secured by the gun. Moreovcr the pocket region gradually diminishes in height and width towards the inward end. Referring to Fig. 3 illustrating the noseend of the bit, when the two components have been oriented upon securement by the barrel of the gun. Therefore the channel 15 is embraced by the pocket region 21 of the sleeve, and moveover the end of the channel Is exposed at the side of croppingblade 24. Accordingly a plastics-covered wire which is to be subjected cutting, stripping and wrapping may be readily directed into the pocket and made to follow the dotted path WP. In this regard, the wire passes above and clear of the piercing blades 18 and 19, and at the root of the pocket is constrained to follow the channel, and then, following the chamfered end of the channel the coveredwire emerges, through cut-out 23, to lie alongside the cropping blade 24. The hole 16 at the nose-end of the bit is duly placed over the terminal-tag to be wrapped, the emergent end of the covered wire is pulled through the cut-out as necessary to take-up the slack, whereupon the gun is started to drive the spindle in the direction of the arrow (Fig. 1). The initial movement causes the excess wire to be cropped-off by the shearing action blade 24 and an edge of channel 15. As rotation proceeds the action of the pocket region is to urge the portion of covered wire which is to the left of point A, (Fig. 3) into the channel. Therefore blades 18 and 19 engage the plastics covering to grip and pierce the insulation 27 at points 28 and 29 as shown in Fig. 4, the wirecore 26 remaining untouched by the blades. As further rotation of the spindle takes place the pad 17 (Fig. 1) forms the wire around the terminal tag. During the wrapping action the wire stripped beyond the piercing blade is drawing out of the bit. In practice it is found that the tubular portion of plastics material which is stripped frond the wire is readily ejected from the bit when another wire-end is inserted preparatory to another joint being made. Instead of forming the piercing blades 18 and 19 during the milling of the channel, they may be incorporated in a small preferably detachable U-shape unit located in a lateral slot which would then be provided in the spindle. Further the tag co-operating end section of the spindle 10 may be made removable so that the bit can accommodate differing sized lengthwise channels 15, for a range of wire diameters, and differing sized central holes 16, for a range of terminal sizes. WHAT WE CLAIM IS:

1. A wire wrapping bit comprising a sleeve and a spindle, the spindle being accommodated within the sleeve and rotatable with respect thereto and having at one end a front-face incorporating a protrusion adapted in operation to form a stripped wire end around a terminal tag to be wrapped, which terminal tag is located in a recess in the said one end of the spindle and enveloped by the free end of the sleeve and the spindle also includes a channel which extends lengthwise from the one end and is adapted to accommodate plastics covered wire inserted into the free end of the sleeve and guided by the channel in the spindle through a wire cropping cut-out in the wall of the sleeve, in which the lengthwise channel in the spindle includes an insulation-piercing means and the free end of the sleeve of the bit is opened out to form a hood, which is of gradually diminishing height and width towards its inner end which forms a pocket in conjunction with the spindle and is arranged such that when the end of the plastics-covered wire is fed into the pocket the wire is guided along the channel from a point remote from the end face and beyond the insulationpiercing means; the pocket also serving, when the spindle is rotated within the sleeve, to urge the covered wire into co-operation with the insulation-piercing means to effect piercing and gripping of the wire covering preparatory to stripping off the covering from the end portion of the wire.

2. A wire wrapping bit according to claim

1 in which the insulation-piercing means comprises a pair of opposed blades.

3. A wire wrapping bit according to claim 2 in which the blades are formed in opposing walls of the channel.

4. A wire wrapping bit according to claim 2 in which the blades are formed in a detachable unit located in a lateral slot formed in the channel.

5. A wire wrapping bit according to any one of the preceding claims in which the insulation-piercing means are located in the channel at a point remote from the one end of the spindle, the distance between the point and the one end determining the amount of covered wire which is to be included in the wrap at the bottom of the wrapped connection.

6. A wire wrapping bit according to claim 5 in which the width of the free end of the sleeve is reduced by the incorporation of flat faces at right angles to the hood.

7. A wire wrapping bit according to any one of the preceding claims in which the spindle comprises two parts, one part ineluding the one end and the channel and the other part comprising the rest of the spindle and the two parts are detachable.

8. A wire wrapping bit substantially as described with reference to and as shown in the drawing accompanying the provisional specification.