GB1592848A

GB1592848A - Male pin plug units

Info

Publication number: GB1592848A
Application number: GB3536076A
Authority: GB
Original assignee: Strix Ltd
Current assignee: Strix Ltd
Priority date: 1977-09-13
Filing date: 1977-09-13
Publication date: 1981-07-08

Description

(54) IMPROVEMENTS TO MALE PIN PLUG UNITS (71) We, STRIX LIMITED, a Manx Company, of "Clonaige", Douglas Road, Castletown, Isle of Man, 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: This invention relates to male pin plug units, and more particularly to pins therefor and the manner of their incorporation in such plug units.

Pins previously incorporated in male pin plug units have generally been made from solid brass, or other highly conductive material. The pins are individually cut from extruded stock and machined to provide the desired taper at the tiF and provision for connection to electrical terminals and for securing the pins in the insulating plug body.

Naturally the cost of such pins is substantial both in terms of cost of materials and of manufacture.

It has previously been proposed that hollow pins be produced from formed up blanks cut from relatively thin sheet metal. Such pins are described in Patent Specification No.

1,370,613, which shows both round and rec tangular section hollow pins provided with integral terminals. In that specification the rectangular section pin is produced by first forming, from a blank two aligned channel sections of different widths, joined at their ends by a short narrow strip integral with the webs of the channel sections. The completed pin is then produced by folding the two channel sections together about the short narrow strip, so that the narrower of the two sections is received between the flanges of the other, with its web extending between the free edges of the said flanges.

The rectangular pin shown in Specification No. 1,370,613 suffers, however, from various disadvantages. Firstly it is not possible to provide four continuous or smoothly rounded corners in the outline of the pin's cross-section due to the inevitable presence of the free edges of the two outer flanges at two od the corners. Again it is very difficult to obtain a smooth taper at the tip of the pin both in respect of its thickness and its width.

Furthermore the exposed free edges of the flanges of one channel render the pin sus ceptible to damage since these flanges are readily outwardly deformed.

According to the present invention, there is provided a hollow pin for a male pin plug unit, having a substantially rectangular outline in cross-section and formed from a flat metal blank, comprising two channel sections each having a web of substantially the same width as that of the other and two flanges disposed one on each side of the web, said channel sections being arranged in opposed relation with said webs parallel and spaced and with each of said flanges extending towards and abutting a corresponding flange of the other channel section, the webs being joined at the tip of the pin.

Such a pin inevitably provides a continuous sheet of metal extending around each of the corners of the pin's cross-section, and thus overcomes the first disadvantage of the earlier pin described above. Also none of the edges of the flanges is exposed thus reducing the risk of mechanical damage.

Preferably the pin is reinforced by a plas tics reinforcing pin extending along its hollow interior at least adjacent the pin's root.

Preferably the pin is formed integrally with a conductive strip extending from its root, which may, for example, incorporate a terminal, contact, or a cold lead olip and which may serve as a means of mounting the pin in the plug unit.

The root of the pin may be provided with an enlarged head which, when the pin is in stalled in a plug unit, engages the plug body.

This feature has the effect of reducing the forces applied to the tip of the pin when the plug unit is withdrawn from a socket. The tip of the pin is thus less likely to fracture, and, in the unlikely event of the tip of the pin fracturing, the channel sections are both maintained within the plug and cannot be left behind as a live element protruding from the socket.

The enlarged head may be formed by in creasing the width of the web at the root of the pin, so that the web forms, for example, a T-shape. Such an enlarged web can be provided on each of the channel sections, or, in the case of a pin having an integral conductive strip formed on one of the channel sections, the enlarged web may be provided only on the other of the channel sections.

The tip of the pin may readily be tapered in respect of both its width and its thickness, thus overcoming the second mentioned disadvantage of the rectangular pin of Specification 1,370,613.

When the pin is to be required to depress the actuator of a socket shutter such as is provided in many domestic electrical supply sockets, the pin is preferably so formed that one of the two adjacent flanges at each side of the pin is wider than the other so that the line on which the two flanges meet is offset from the plane midway between the webs.

The invention extends to a male pin plug unit incorporating one or more of the novel pins described above and having an insulating body, wherein the or each pin passes through a closely fitting aperture in the insulating body at or adjacent the pin's root. This arrangement maintains the correct relative orientation of the two channel sections.

Where a plastics reinforcing pin is pr vided it is preferably mounted on a plate which is secured to the insulating body. The reinforcing pin is then preferably thickened where it emerges from the root of the hollow pin.

Where the or each pin is provided with an integral conductive strip extending from its root, the or each conductive strip is preferably clamped in place within the insulating body by a clamping member. Preferably the clamping member also comprises the plate mounting said reinforcing pin(s).

The plug unit is preferably so arranged that the hollow pins are inserted into the insulating body in the same direction as the clamping member so that a simple manufactoring process may be adopted.

Again the reinforcing pins are preferably thickened where they emerge from the pins' roots.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: FIG. 1 shows a metal blank; FIG. 2 shows a front view of a hollow pin with an integral conductive strip, formed up from the blank of FIG. 1; FIG. 3 is a side view of the pin and conductive strip of FIG. 2; FIG. 4 is an end view of the pin of FIG. 2; FIG. 5 is a cross-section taken on the line X-X of FIG. 2; FIG. 6 is a cross-sectional side view of a pin in accordance with the invention in corporated in a plug unit; FIG. 7 is a view similar to FIG. 5 but showing a second embodiment of the invention; FIG. 8 is a view similar to FIG. 5 but showing a third embcdiment of the invention; FIG. 8A is a cross-section of a reinforcing pin for the pin of FIG. 8; FIG. 9 is a view of portions of a metal blank for forming a pin with an alternative form of taper at its tip; FIG. 10 is a view of a metal blank cor responding to FIG. 1 for forming a further embodiment of a hollow pin according to the invention and FIG. 11 is a front view of a pin formed from the blank of FIG. 10.

FIG. 1 shows a sheet metal blank, of for example brass, for forming a hollow pin for a male pin plug unit. To form the pin, shown in FIGS. 2 to 6, flanges 1 are first bent upwardly out of the plane of the paper through 90 degrees about dotted lines 2, to form two channel sections. Each channel section has a web 3 of the same width as that of the other, the webs being tapered at their adjacent ends down to the width of a strip 4 which joins them. Tapered free ends 5 of flanges 1 are each then bent about a respective vertical axis so that they are aligned substantially vertically above the corresponding edges of the tapered parts of the webs 3, and integral conductive strip 6, incorporating a terminal 7, is bent downwardly out of the plane of the paper through 90 degrees about dotted line 8. The channel section adjoining conductive strip 6 is then bent upwardly out of the paper and over through 180 degrees, bending about dotted lines 9 and 10 at the ends of strip 4, and to a lesser extent about dotted lines 11 and 12, to form the completed pin as illustrated in FIGS. 2 to 5.

As best shown in FIGS. 3 and 4 the two channel sections are arranged in side by side relation with their webs 3 parallel and spaced by the flanges 1 which extend between the webs with their free edges in abutment, the webs being joined at the tip of the pin by strip 4. The pin has a substantially rectangular outline in cross-section (FIG. 5) with smoothly rounded edges, and has a hollow interior also of substantially rectangular crosssection. The tip is tapered both in respect of its width and its thickness. Widthwise taper is introduced by cutting out triangular portions from the sides of the webs when stamping out the blank, to produce tapered webs 3, and by bending the free ends 5 of the flanges inwardly, as described, after the flanges have been bent up along the lines 2. Taper is introduced into the thickness of the pin thus enabling the webs 3 to be bent about lines 11 and 12 as well as on either side of the strip 4 by tapering the width of the free ends 5 of the flanges, the taper on the flanges is most conveniently introduced again by appropriate shaping of the blank.

The pin is integrally formed with the conductive strip 6 extending from its root and incorporating terminal 7, thus eliminating the need to connect the pin to a terminal through a separate conductive strip. It will be readily appreciated that the conductive strip could incorporate, instead of the terminal 7, other forms of electrical connector such as a simple contact or a cold lead clip.

FIG. 6 shows a hollow pin incorporated in a plastics plug moulding comprising a base part 13 of an insulating plug body, a clamping plate 14 and a cover 15. The pin passes through a closely fitting aperture 16 in the base part 13, which serves to hold the two channel sections together, and is positively located further by having the integral conductive strip 6 clamped between the base part 13 and the clamping plate 14, a reinforcing pin 17 for the hollow pin is integral with clamping plate 14. Reinforcing pin 17 serves to locate the root of the hollow pin firstly by assisting in the maintenance of the relative orientation of the two channel sections, and secondly by providing the hollow pin with support against axial thrust, a thickened portion 18 extending around three sides of pin 17 and abutting with the end of the hollow pin. Pin 17 also stiffens the hollow pin, and renders it less liable to buckling and crushing. The stiffening function of reinforcing pin 17 is particularly important at the root end of the hollow pin where the maximum stress occurs, and thus whilst pin 17 extends along the whole of the length of the hollow pin, it is especially desirable that the reinforcement be provided at least at the root end.

As will be readily appreciated, the plug construction illustrated permits a simple and advantageous assembly process by virtue of the fact that both the hollow pin and the clamping plate are set in place in the base part 13 of the plug body from the same direction.

It will be seen that the cross-section of the hollow pin permits the provision of a reinforcing pin of substantial cross-sectional area as compared to the overall cross-sectional area of the hollow pin, and certainly more so than would be the case if a reinforcing pin were to be provided for the rectangular section pin of British Specification No.

1,370,613. The reinforcing pin can accordingly be made robust for given outside dimensions of the hollow pin.

FIGS. 7 and 8 show alternative crosssectional shapes for the hollow pin. FIG. 7 shows a pin with channel sections each of which has two flanges 1 of unequal width, thus providing that the line on which the two adjacent flanges meet at each side of the pin is offset from the centre of the plane midway between the webs. Such a plug is suitably adapted to actuate a socket shutter, since the shutter's actuator will ride over the surface of one of the wider flanges rather than on the line on which the flanges meet.

In FIG. 8 the flanges are additionally folded adjacent their free edges so that the free edges face inwardly towards the centre of the pin.

FIG. 8A shows a suitable cross-secticn for a reinforcing pin to reinforce the hollow pin of FIG. 8, which would enable the reinforcing pin to give additional support to the hollow pin by holding the adjacent flanges in contact where they are received in grcoves 19.

Fig. 9 shows an alternative shape for the centre of the blank which provides an alternative means for introducing taper at the pin's tip. To form the pin the flanges 1 are bent up and the two channel sections brought into side by side relationship as before but with folding taking place about dotted lines 20 and 21, triangular portions 22 are then folded about the dotted lines 23 until they are located in the triangular shaped space which is defined between the pin tip at line 20 and the edges 24 of the flanges.

FIG. 10 shows a sheet metal blank similar to that shown in FIG. 1. However, the web 3 of the lower channel section terminates in an enlarged T-shaped end 25, formed by means of cuts 26 made in the blank at the ends of flanges 1. When the blank of FIG. 10 is bent as described above with reference to FIG. 1, a pin as shown in FIG. 11 is produced.

WHAT WE CLAIM IS: 1. A hollow pin for a male pin plug unit having a substantially rectangular outline in cross-section and formed from a flat metal blank, comprising two channel sections each having a web of substantially the same width as that of the other and two flanges disposed one on each side of the web, said channel sections being arranged in opposed relation with said webs parallel and spaced and with each of said flanges extending towards and abutting a corresponding flange of the other channel section, the webs being joined at the tip of the pin.

2. A pin as claimed in claim 1, further comprising a plastics reinforcing pin extend ing along its hollow interior, at least adjacent to the root of the pin.

3. A pin as claimed in claim 1 or 2, further comprising a conductive strip extending from the root of the pin formed integrally therewith.

4. A pin as claimed in any preceding claim, comprising an enlarged head at the root thereof which, when the pin is installed in a plug unit, engages the plug body.

5. A pin as claimed in claim 4, wherein the web of at least one of the channel sec

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ends 5 of the flanges, the taper on the flanges is most conveniently introduced again by appropriate shaping of the blank. The pin is integrally formed with the conductive strip 6 extending from its root and incorporating terminal 7, thus eliminating the need to connect the pin to a terminal through a separate conductive strip. It will be readily appreciated that the conductive strip could incorporate, instead of the terminal 7, other forms of electrical connector such as a simple contact or a cold lead clip. FIG. 6 shows a hollow pin incorporated in a plastics plug moulding comprising a base part 13 of an insulating plug body, a clamping plate 14 and a cover 15. The pin passes through a closely fitting aperture 16 in the base part 13, which serves to hold the two channel sections together, and is positively located further by having the integral conductive strip 6 clamped between the base part 13 and the clamping plate 14, a reinforcing pin 17 for the hollow pin is integral with clamping plate 14. Reinforcing pin 17 serves to locate the root of the hollow pin firstly by assisting in the maintenance of the relative orientation of the two channel sections, and secondly by providing the hollow pin with support against axial thrust, a thickened portion 18 extending around three sides of pin 17 and abutting with the end of the hollow pin. Pin 17 also stiffens the hollow pin, and renders it less liable to buckling and crushing. The stiffening function of reinforcing pin 17 is particularly important at the root end of the hollow pin where the maximum stress occurs, and thus whilst pin 17 extends along the whole of the length of the hollow pin, it is especially desirable that the reinforcement be provided at least at the root end. As will be readily appreciated, the plug construction illustrated permits a simple and advantageous assembly process by virtue of the fact that both the hollow pin and the clamping plate are set in place in the base part 13 of the plug body from the same direction. It will be seen that the cross-section of the hollow pin permits the provision of a reinforcing pin of substantial cross-sectional area as compared to the overall cross-sectional area of the hollow pin, and certainly more so than would be the case if a reinforcing pin were to be provided for the rectangular section pin of British Specification No.

Fig. 9 shows an alternative shape for the centre of the blank which provides an alternative means for introducing taper at the pin's tip. To form the pin the flanges 1 are bent up and the two channel sections brought into side by side relationship as before but with folding taking place about dotted lines 20 and 21, triangular portions 22 are then folded about the dotted lines 23 until they are located in the triangular shaped space which is defined between the pin tip at line

20 and the edges 24 of the flanges.

FIG. 10 shows a sheet metal blank similar to that shown in FIG. 1. However, the web

3 of the lower channel section terminates in an enlarged T-shaped end 25, formed by means of cuts 26 made in the blank at the ends of flanges 1. When the blank of FIG. 10 is bent as described above with reference to FIG. 1, a pin as shown in FIG. 11 is produced.

tions increases in width at the root of the pin.

6. A pin as claimed in any preceding claim, wherein one of the two adjacent flanges at each side of the pin is wider than the other.

7. A pin for a male pin plug unit, substantially as herein described with reference to Figures 1 to 5, 7, 8 and 8A, 9.

8. A male pin plug unit comprising one or more pins as claimed in any preceding claim and an insulating body, wherein the or each pin passes through a closely fitting aperture in the insulating body.

9. A plug unit as claimed in claim 8, further comprising a plate secured to the plug body and having at least one plastics reinforcing pin mounted thereon.

10. A plug unit as claimed in claim 9, wherein the reinforcing pin is thickened where it emerges from the root of the hollow pin.

I1. A plug unit as claimed in any of claims

8 to 10, wherein the or each pin comprises an integral conductive strip extending from the root thereof, and comprising a clamping member for clamping the conductive strip in place within the insulating body.

12. A plug unit as claimed in claim 11, when appendent to claim 9 or 10, wherein the clamping member also comprises the said plate.

13. A plug unit as claimed in claim 11 or 12, wherein the hollow pins are inserted into the insulating body in the same direction as the clamping member.