US2947053A - Plastic beads - Google Patents

Description

Aug. 2, 1960 w. T. SANDERSON' PLASTIC BEADS Filed Aug. 28, 1957 Ir -Nil? TTORNEYS se M Claims priority, application omnnnaiasept' 20, 1956 W s 'clannshtci. 24-217 This invention relates to plasticbeadsofjthef kind referred to) which are made'of resilient plastic material such as polythene and in which at least, one of a pair of beads is formed with a neck carrying ahead and the other is formed with a socket to accommodate the head which socket is entered through amouth of smaller cross-section than the socketinterior, the head onrone bead and the mouth on the other being so shaped and dimensioned in relation to one another that the head will not ordinarily pass through the mouth but, due to the resilience of the plastic m-aterialg-can be forced through with a snap action when it is desired tojoin two beads together, the head, neck and socket being so dimensioned that the head is smaller than the socketso as to permit of relative angular movement between t-he beads with free play of the head in the socket.

heads of substantially spherical formand to form the mouth with a circular opening. This form of construction has been found quite satisfactory for uncoated polythene heads, but it is often required that beads should be coated,for example bybeing' metallised or' parled. Many of these coatingshavenot gotthe elastic properties ofpolythene it is found that,':if a circular mouth-and errauy "cylindriqahl 9 h n of a coated bead may split after rone or more insertions segmgnt g1 1i 2 mi p nhi a g spherical bead are'used asdscribed above, thelrcoatihg of a headin the socket of a coated bead due to the distortion of the socketed head. The effect of this distortion is that an annular ring of the coating material in the immediate neighbourhoodoff-the socke mouth must increase'in circumferencefin thratio of he 'eter of the bead head to i-that of 'the-unstretch v unless itis"sufiieient lyelastic t'o "d'o' }s'o, one" splits occur. This splitting mightjbe relatively unimpo'r tant if the coating could be made to adhere tothe' poly thene but, as is wellyknown, it isvery difiicult to stick the result that the coating 7 anything to polythene with peels from the bead.

It is an object of the present invention to provide an made approximately equal to the area of the mouth of a socket, the headin said plane and the mouth being shaped differently so that the head will not ordinarily pass through the mouth but, due to the resilience of the According to another aspect of this invention, the periphery 'of the mouth of the socket of one bead is'made greater than that of a head on another bead atthe section of maximum area in a plane normal to the direction of insertion of the head in a socket, the mouth being t (hereinafter described as plastic beads of the kind s d' nd. 'm h; is mo c lanzflhehea r 2,941,053 Patented lh gshaped difierently from the head and of-such size that the head will not ordinarily pass through the mouthbut, due to the resilience of the plastic material 'canxbe forced throughvvith a snap action when it is desired to join two beads together. 7 head is pressed into a' socket pfa coated .heQd,---an,an; nularring of coating material in the neighbourhood qf the mouth is deformed butnot increased in peripheral length and thereby the tendency to split is greatly ed: 5 a; t "1; Most-conveniently the 1 headris fjcircular ectio f e mp ay ei phe al f or s idthsad may be, outwardly fromthe plane ofrpaximum crossesection, of conical form, the-conicalpartcf therheadgheing are ranged with its, apex directed outwardly. Forl example,

' the he'ad may be "conico-spherical inshape, :tha t isto say the headis formedofa hemisphere which 'at'its. diametral plane is joined to a .circular cone the conical part of the head being arranged with its apex directed; outwardly. I, 1 r j According to yet another aspect of the, invention, in plastic beads ofithe kind irefer red to, the head on one head is formed with a circular section in a planenormal to the direction of insertion of the head in a socket and the socket mouth on another head is in the form of an aperture which is non-circular, the radial dimensions of the socket'mouth being in someregions greater than and in some regions less thaHFthC radial dimensions of said circular section head so that the area of the mouth K of the socketis a roximat l i Heretofore 1t has been universal practice to make the pp e y equal to cross-section area of, the head in said plane;

A socket with such 1a mouth may be formed, for example, 1

" by a circular cylindrical cavity in thebody of head a are short arcuate portions of the cavity wall 7 when it is desired to join the two beads together.

7 Figure 3 is an end view} of'the head of Figure with three segmentallips, .Such-a-mouth formed during moulding ofa beadb sin adore pinlofl'gen;

cuts around; its surf aee end to. t

length attheir ends do not:

ma er e ie' ti iih rm ich is particularly desirable to enable the as possible. To-this end, conical ended heads may be used as described above and preferably also the lips on the mouthof the sockets are shaped so as to have an; outer face 'which slopes from the socket wall inwardly towards the interior of the socket so as to facilitate the sliding in of a head. Preferably also the lips have an inner face which preferably extends at right angles to the axis of the socket so as to oifer the maximum resistance to the withdrawal of a head.

The invention also includes within its scope a plastic head of the kind referred to and having a head and a socket with a mouth, the head in the plane of maximum cross-sectional area normal to the direction of insertion in a socket of another bead being shaped differently in. cross-section from the mouth of the socket.

In the following description, reference will be made to the accompanying drawings,- in which Figure 1 is a cross-sectional view of a bead,

Figure 2 is an end view of the head of Figure 1. lookving in the direction of the arrow A,

a 1 looking inthe direction' ofthe'ar-row B,

By this form of constructign, whe'ma L i 7 ch 4 Figure 4 is a view in elevation of part of a core pin for use in moulding the bead of Figures -1 to 3, and

Figure 5 is a section along the line 5-5 of Figure 4.

Referring to Figures 1 to 3 there is illustrated a bead formed ofpolythene and having a generally spherical body 10. "Protruding from this body is a nee'k'll having a head '12, this head being formed at its outer end in the shapeof a frustumof, a come 13 with the apex of the cone directed outwardly. The head is joined to the neck by a very s'hortsectionib lwhich is also of generally conical form with anobtuse apex angle such that this surface is almost-- at right'angles to the axis of theneck and head: 1

The body contains a cavity 15 with a mouth "16 formed by'the inwardly-directed lips 17-. These lips are each formed as a web across the mouth -of-the cavity 15, so that the mouth entrance is or generally triangular form withrounded corners as most clearly seen in'Figure 2 The mouth 1'6 is madeof such size that the crosssectionarea'of the mouth at the lips. is approximately equal to the maximum cross-sectional area of the head 12 in a direction perpendicular *tothe axis of the neck and head. can "be inserted through the mouth into a socket of a similar bead with a snap action in a manner similar to that described in specification of British Patent No.

750,737. By 'formingthe mouth of triangular form as described above with its cross-sectional area approxirnately equal to that of the head, very little distortion of the body of a'bead occurs when the'head of another bead is inserted or withdrawn from the socket 'of the first bead. This arrangement has particular advantage if the body of the bead is coated with a pearl or other hard finish. Most pearly and metallising finishes for plastic beads tend to split or peel off it the bead 'is distorted and the arrangement of the present invention-thus minimisesthe possibility of the coating peeling;

The particular form of head described above enables the head to be insertedeasily into the socket since the conical-surface 13 of the-head, as it is inserted in the mouth, gradually distorts the lips of-the mouth; Greater force, however, -is necessary to pullthe beads apart than- It will'be seen that the head of one bead lips inside the cavity, and the insertion of the head in 21, which may conveniently be formed by milling, these grooves being shaped so as to 'form the required lips 17 on the mouth 16 of the socket. It will be seen that the grooves 21 are of such length that their ends do not quite meet so that there are short arcuate portions of the cavity wall beween he lips.

I claim: 7

1. In a multiple bead assembly formed by identical beads, .a head of resilient plastic material of the type which may be snapped one into the other comprising a body portion of which a part thereof has an integral neck with a head thereon wider than said neck, an opposite partof the'body portion having a cavity extending thereinto with a mouth portion which is triangular in cross section, said mouth being formed by spaced segmental lips which defineishoulders inside the cavity, said lips being inwardly inclined, the shoulders of said mouth portion being adapted to engage .the head .portion of an adjacent bead to hold 'the'beads together, and said head portion being frusto-conical in longitudinal cross section so that when two adjacent beads are interengaged, the frusto-conical head is received in the cavity and is held by the shoulders defined by the segmental the cavity taking place with distortion of the lips with no substantial distortion of the body portion beyond the lips.

2. A bead according to claim '1, in which the internal shoulder of each lip'is at right angles to the longitudinal to join'themtogether since the inner taceof the lips 17,- as shown in Figure" 1 are "arranged to extend at right angles to theaxisof =thesocket and thus to'engage on the rear face 14 of the head whein the beads are pulled apart. I

The form of beadillus trated in Figures 1 to 3 is most conveniently made: by moulding and the-"socket shown in'Figures '1 and 2 maybe'made Whilst'th'e head is being moulded by using a'core pin 20 as sho'wriin' Figures 4 It willbe'seen that the core pin'has three grooves axis of the bead. v

3. A bead according to claim 1, in which the mouth portion has a cross sectional area at the lips approximately equal to the maximum cross sectional area of the head in a direction'perpendicular .to the longitudinal axis of the bead.

References Cited in the file-of this patent UNITED STATES PATENTS

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