US2521144A - Flexible and expansible band - Google Patents

Description

Sept. 5, 1950 G. G. BERGH FLEXIBLE AND EXPANSIBLE BAND Filed May 1, 1948 Patented Sept. 5, 1950 FLEXIBLE AND EXPANSIBLE BAND George G. Bergh, Attleboro Falls, Mass, assignor to Bergh Bros. 00., Inc., Attleboro Falls, Mass, a corporation of Massachusetts Application May 1, 1948, Serial No. 24,511

8 Claims.

. 1 1 This invention relates to flexible and expansilole bands and more particularly to expansible metallic straps, bracelets, necklaces, or similar bands used in supporting ornaments, and deriv- 'ing spring tension from the coiled walls of the of each strip lie alongside each other with edges contiguous and with the center of the outer strip lying directly outside the contiguous edges of the inner strip. In the fully expanded position, the turns or wrappings separate but the out-turned edges of the inner strip and the in-turned edges of the outer strip interlock preventing further expansion and separation.

The amount of expansion provided by the above described conventional construction often is not suflicient to accommodate a person with a large hand and still fit snugly to his wrist. Also, in case it is desired to fit a necklace over the head of a person, the expansion afforded by the conventional band is not sufiicient to allow it to fit closely around the neck and also pass over the head.

In attempting, however, to increase the ratio of expansion to cross-sectional area, one is restricted by certain physical limitations with the conventional construction. That is, the width of the strips controls the expansib'iiity, but if the strips are widened without increasing the crosssectional area, first, the spring tension of the band is increased rendering expansion more difficult, and second, since the cross-sectional area is not increased, the strips must be wrapped at greater slanting angles. This latter .fact operates against effective expansion by increasing the amount of cross-sectional contraction per unitof longitudinal expansion thus reducing the benefit of-the increased width. Furthermore, since the inner strip is of necessity shorter than the outer strip, its cross-sectional area contracts more than that of the outer strip whenthe band is ex- "panded. This fact is more pronounced at greater angles of slant, rendering it more diilicult when the angle of slant is increased to attain effective locking of the in-turned and out-turned edges at the point of full expansion.

Accordingly, an object of my invention is to provide a construction which is effective for intioned above.

ar-easing the ratio of expansion to cross-sectional area of a band without increasing the width of the strips and without increasing the angle of slant at which the strips are wrapped.

in order to accomplish this object, I employ an inner strip with its edges notched forming teeth the ends of which are bent outwardly. Outside and around the inner strip, I wrap an outer strip with inturned edge flanges. In the contracted state, the teeth of the inner strip intermesh and the flanges of the outer stripcome flush up against each other, while in the fully expanded state, the strips may separate until the outwardly bent teeth on the inner strip interlock with the inturned flange of the outer strip. Th-us, the width of the outer strip has not been increased, the same angle of slant has been maintained, but due t the intermeshing of the teeth, the inside strip can be made wider and the band is capable of greater expansion.

A further feature of my invention is the provision of notches in the inner strip substantially wider than the teeth formed by the said notches. This feature insures free access of the teeth into the notches when the band is in the contracted state and is advantageous because the turns-oi the band do not separate at right angles to each other when the band is expanded.

An additional feature of my invention is the provision of a crimp in the side walls of the band when it is formed rectangular or parallelepiped shape. This feature insures interlocking of the outwardly bent tips of the teeth of the inner strip and the inturned edges of the outer strip when the band is expanded, and minimizes the effect of the greater contraction of the inner strip men- This feature also serves to decrease the length of the outer strip, fitting it more closely to the inner strip.

These and other features of the invention will be best understood and appreciated from the vfollowing description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings, in which:

Fig. l is a view in perspective of a section of the band with the outer strip in part cut away in order to show the inner strip and on a greatly enlarged scale,

Fig. 2 is a view in side elevation with the outer strip cut away, and showing in detail the intermeshing of the teeth in the inner strip,

Fig. 3 is a view in side elevation showing the inner strip fully expanded, and

inner strip partially expanded. V

In the preferred embodiment of my invention, I employ an inner metallic strip ID in the edges of which are cut notches H, leaving teeth II, the said notches I I being substantially wider than the teeth I2 as is shown in Fig. 2. The outer ends of the teeth l2 are bent outwardly forming flanges, but it is to be noted that the notches II continue inward toward the center of the strip II! from the line on which the teeth I2 are bent outwardly.

The inner strip I is wound helically in turns or wrappings of rectangular form with the sides of such length as to permit the teeth I2 of the adjacent edges to intermesh upon winding as shown in Fig. 1.

Outside and wound helically into the same form as the inner strip I0, is a metallic outer strip M which encloses the helix of the inner strip 10. The outer strip [4 serves the purpose of ornamentation and therefore may be made of precious or polished metal. The edges of the outer strip M are bent inward forming the flanges I5. Including the flanges l5, the width of the outer strip l4 equals the distance between the outer extremities of the teeth l2 in one edge of the inner strip l0 measured across to the base of the notches l I in the other edge of the inner strip ID, as designated by the line in Fig. 4.

From this it can readily be seen that by notching and intermeshing the inner strip In its overall width including the teeth 12 in both edges can be made substantially greater than the width of the outer strip l4 and still maintain the same number of winds per inch. And, it further follows that the greater the depth of the notches for a given number of winds per inch, the greater will be the amount of expansion.

The device of my invention is shown in two extreme conditions, one in which it is fully contracted (see Figs. 1 and 2), and the other in which it is fully expanded (see Fig. 3). In the fully contracted position, the flanged edges of the outer strip 14 come flush up against each other and the teeth l2 of the inner strip l0 intermesh. In the fully expanded position, the teeth I2 of the inner strip 10, by means of their out-turned ends, engage the flanges l5 of the outer strip M.

It will be apparent that inner strip H! may be wound as a helix upon a rectangular or other shaped mandrel and then the outer strip 14 may be wound upon formed inner strip while the latter is still supported in its mandrel. A crimped depression may be swaged into each turn of the outer strip adjacent the vertices of each turn thus locally widening the strip and providing a slight clearance between its side edges as shown in Fig. 1. This feature of construction results in increased flexibility of the band as a whole.

Inasmuch as the strips l0 and M are made of substantially resilient metal, the band will tend to remain in the fully contracted position, if wound initially in that position. However, since variations in winding or otherwise will readily suggest themselves to those skilled in the art, it

is not intended to limit the invention to the pre- 7 ciseembodiment herein described, but rather to confine it to the scope of the appended claims. Therefore, having thus disclosed my invention and described in detail an illustrative embodiment its edges so constructed and arranged as to inter mesh when its edges lie contiguous in the helix, inturned marginal flanges on the outer said strip and out-turned flanges at the extremity of the said teeth on the inner said strip, the said flanges constructed and arranged to meet when the strips are pulled apart.

2. A flexible and expansible band comprising an outer strip of flexible metal, an inner strip of flexible metal, an inturned flange on each margin of the said outer strip, each margin of said inner strip being notched to form spaced teeth and notches, an out-turned flange at the extremity of each of the said teeth, the said inner strip being helically wound and so constructed and arranged that when its opposite margins lie relatively adjacent in the helix, the teeth of one margin flt into the notches of the adjacent margin, and the outer strip being helically wound about the inner strip in close proximity thereto with its margins meeting flush against each other when in contracted position, and its inturned flanges lying between the out-turned flanges of the said teeth whereby contact between the said flanges will be made when the band is expanded thereby limiting further expansion.

3. A flexible and expansible band of the character described in claim 2, further characterized by the notches being wider than the teeth thus ensuring unobstructed intermeshing when in the contracted position.

4. A flexible and expansible band of the character described in claim 3, further characterized by the said strips being pressed into rectangular form, and the said outer strip being crimped adjacent to each fold vertex in order to insure contact between the inturned and 0utturned flanges.

5. A flexible and expansible band for ornamental purposes comprising an inner strip having teeth of uniform size and shape in its edges bent outward at their extremities and spaced unlformly along the edges of the said inner strip at intervals substantially greater than the width of the said teeth, the said inner strip being helically wound such that the teeth of one margin thereof will flt in the spaces between the teeth of the contiguous edge when the band is contracted, and an outer strip having an inturned flange on each margin thereof, the outer strip being helically wound around the said inner strip in close proximity thereto with its margins meeting flush against each other when in contracted position, and its inturned flanges lying between the outturned flanges of the said teeth whereby contact between the said flanges will be made when the band is expanded thereby limiting further expansion.

6. A flexible and expansible band of the character described in claim 5, further characterized by the outer band having a width equal to the width of the adjacent inner band measured between the extremities of the teeth on one edge and the base of the space between the teeth on the other edge 7. A flexible and expansible band of the character described in claim 6, further characterized by the strips being composed of resilient metal,

and having parallel edges.

8. A flexible and expansible band for ornamental purposes comprising an inner strip of flexible metal, the said inner strip having uniform rectangular notches cut in its edges at equal intervals along its said edges, teeth formed by the notches, the saidteeth being of less width than the said notches and being bent at their extremities so as to form upstanding flanges, an outer strip of flexible metal with its edges bent so as to form depending flanges, the width of the outer strip and flanges being equal to the distance measured on the inner strip between the base of the notches on one side and the extremity of the out-turned teeth on the other side, the said strips being helicaliy wound with their edges overlapping and bent into rectangular shape.

GEORGE G. BERGH.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Armstrong July 25, 1911 Eklund Sept. 24, 1918 FOREIGN PATENTS Country Date Germany July 2'7, 1930

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