US2600163A - Finger ring stretcher - Google Patents

Description

June l0, 19.152v E G, HENRY 2,600,163

FINGER RING STRETCHER Filed Sept. 25, 1946 Patented June 10, i952 Earle G. Henry, Wilmette,.lll.

Application September 25, 1946, SerialNo. 699,211

2 Claims.

In-the past, finger ring stretchers have been made consisting of a rounded, tapered, collapsible and expansible, hardened metal arbor, an operating handle and Vother auxiliary features. In operation,- the arbor was collapsed to its minimum sizeby movement of the handle in one direction, the ring to be stretched was slipped along the -tapered arbor to such a position that it fitted closely thereon, whereupon. movement of the handle in .the opposite` direction would forcibly expand the arbor and the ring likewise,` stretching Vthe metalof the latter. In case one stroke of the handle wasinsucient to stretch the ring the requiredamount, the operation could be repeated as often asnecessary, for each time the ring was stretchedV itcould beslipped farther along the tapered arbor and be expanded to increasingly larger diameters on successive strokes. While some ring stretchers of this general type have been made which would do the work satisfactorily, none of them have been commercially successfulfchiefly becausethe actual mechanisms have been-excessivelyinconvenient to set up and operate, and diiicult and expensive to produce.

The principal object of the present invention is to provide -a Yring stretcher, of the general type described above, but having a novel general'` arrangementv and novel features which permit the device v to be constructed' from relatively few parts, all 'simple and inexpensive to produce, and the device as a whole to-be light in weight, simple to assemble and dis-assemble, and efcient in operation.

I attain the aforesaid object by means ofthe improvedv construction illustrated in the accompanying drawing, in whichs- Figure 1 is a side view of a-nger ring stretcher embodying the present invention in its preferredlform, with the parts in their normal,- idle position and the operating lever shown in kbroken lines atthe end of an arbor-expandingv stroke; Fig. 2 is a section on line 22 of Fig. 1,-the upper part of the link that serves as 'a fulcrum'for thelever being broken away, showing the arbor expanded as it is when the lever is down; Fig.v 3 is a top plan view of the device-appearing in Figs. 1 and 2; Fig. 4 is a transverse section throughthe sleeve-like arbor blank,A onv a much larger scale, needing only to be divided into four segments to become a nished arbor; Fig. 5 is a section on line 5-5 of Fig. l through the arbor closed on the stem by which it isexpanded, showing theA four segments in edge contact with each other, the scale being the same as in Fig. 4;*Figs. 6 and 7 are cross sections on lines S-I-and 'I-JI of' Fig. 2, respectively, but on a larger scale; Fig. 8 is a perspective View of the split spring ring or clip that holds the lower ends of the arborsections ina'yielding grip; Fig. 9' is a perspective View of the split spring ring or clip at the other end of the arbor.

Referring to theV drawing, in` detail, II isv a channel-shaped piece of relatively thin sheetmetal, which'formsthe principalfstructural element of the base lof the device.y Partially enclosed and concealed -by thechannel II, :andcemented into position therein', isa wooden ller I2,

to the bottom surface'ofwhich-a 'sheet of felt I3 wood ller being out away, as vat I2a, to'makeiroom for member'lll. I5"is`a round, tapered,

metal stem,A rigidly 'attachedi'to baseparts I I andy I4 by meansV of the' nut I6. I1 is a U-shaped part, or fork, made of relatively thick'sheet metal and rigidly welded or riveted at its closed end to base parts 'I I and III- I8 is a link, pivotally connected'at one end to the' fork I1,.by means of'a pin I9'. 20' is a lever, formed from relatively thick sheet metal' and'pivotally connected to the upper end of link I 8 by means of a pin 2 I that is parallel'to pin' I 9.

22 is' a rounded, tapered,V metal arbor consisting of the fourv separatesegments, 24, 25' and 26. Segments 23 and 24 are pivotally'connecte'd to the lever 20 by means of'a pin 2l. which ts within round, transverse holes in segments 23 and 26, preventing relative vertical dis'- placement of these two segments. 29 is a similar pin which similarly prevents relative Verticaldisplacement of segments 24 and 25. Hence the arbor always moves vertically as a unit. Pin 21 is at right angles to one of the two planes along which the arbor is divided, while pins 28 and v29 are at right angles to the other of such planes;A and so the lateral movements of each segment can only be at right angles to one of these planes while paralleling the other.

30 is a clip in the form of a C-shaped springsteel collar or split ring which lits within a groove 22a near the upper end of arbor 22 and tends to squeeze the latter toward its collapsed or minimum size. 3l is a similar but larger collaror split ring ywhich nts within a similar groove -22b 28`is a pinl near the lower end of the arbor and tends to collapse the latter. 32 is a coil spring which fits loosely around the lower, cylindrical portion I5a of Stem I5 and presses upward against the bottom surface of arbor 22, tending to lift the arbor into its upper or collapsed position.

When the ring stretcher is standing in its normal or idle position, spring 32 is holding arbor 22 at the upper end of its stroke, spring collars 30 and 3| are holding the arbor in its collapsed condition, and the outer or handle end of lever 20 is tilted upward, as shown in full lines in Fig. 1. When a finger ring of relatively small diameter is passed over the top end of the arbor and allowed to drop, it will come to rest in contact with the periphery of the arbor and relatively near to the top. A larger ring will drop farther down on the arbor before coming to rest. Then, when the lever is pushed forcibly downward, for a full stroke, into its lowest position, as shown in broken lines in Fig. l, the arbor is forced downward and expanded to its maximum size by the wedging action of the tapered stem I5; thereby stretching the ring by a definite, small amount, compressing spring 32 and expanding the spring collars 30 and 3I. In some cases, only a fraction of a full stroke may be required to stretch the ring sufficiently, while in other cases one or more additional full or fractional strokes may be required.

Finger rings which have local weaknesses, as is A the case with many rings designed for holding large gems, cannot, of course, be safely stretched on this type of stretcher, since such a ring would break at the weak place before stretching of the remainder of the circumference could occur.

The range of swinging movements of lever 20 is small, preferably not more than twenty degrees, half above and half below a horizontal plane. Consequently, when operating the device, the force which the hand of the operator exerts on the lever acts almost entirely in a downward direction, so that maximum force may be exerted Without any tendency to cause the device to slide along the surface on which its base may be resting. thrust of the lever is transmitted to the base a short distance from one end of the latter, while the base extends many times that distance underneath the long arm of the lever, the device cannot tilt when the lever is pressed down. Consequently, it is unnecessary to provide means for clamping this ring stretcher to some rigid, stationary object, as is the case with some other ring stretchers of this general type which have been made; and my ring stretcher, unlike these others, may at any time be instantly picked up and moved from place to place and may be operated on any firm, approximately horizontal surface.

For stability, the base of my device is made relatively wide, but by using the sheet-metal channel II, combined with the wooden filler I2, the desired width and rigidity are secured without making the base unduly heavy. Moreover, this sheet-metal channel is wellY adapted for receiving a handsome, economical and durable finish, such as plating or enamel.

The sheet-metal, channel-shaped lever 20 is not only strong and light and adapted for economical production and finishing, but its various features are peculiarly adapted for efficiently performing their various functions. The handle end is broad and comfortable for receiving downward pressure from the palm of the hand. The two side flanges 20a and 20h, of the lever, one on each Furthermore, because the downward t side of the arbor 22, and through which the pin 21 extends, press downward on both ends of the pin, minimizing the tendency to bend or tilt the pin. The fulcrum of the lever is located at the two widely separated ends of the pin 2I, which also extends through iianges 20a and 20h, so that undesirable movements of the lever, sideways or angularly about its longitudinal axis, are minimized. This smooth, controlled movement is of great help in stretching valuable rings, where one must judge by the sense of touch how much force it is safe to apply without cracking the ring.

The three pins 21, 28 and 29 maintain the four segments 23, 24, 25 and 26 of the arbor in a fixed vertical relationship but allow free horizontal movements of the segments toward and from each other, with the meeting edge faces at all times parallel to each other. Moreover, since the three pins prevent mutual rotational movements of the four segments about their vertical axes, and since the segments are pressed into rm contact with the round, central stem I5, by the spring'collars 30 and 3l, during all stages of normal operation of the device, the four segments at all times remain uniformly distributed circumferentially around the stem. That is, the four longitudinal gaps between the segments remain equal to each other at all stages, from complete collapse of the arbor, when the gaps close up completely, to maximum expansion. Without this circumferential control, all four of the segments, when the arbor was fully expanded, might be crowded together, so that three of the gaps would practically disappear while the remaining gap would be so wide as to produce a definitely flat place on once side of the ring.

Pin I9 is a tight press fit in the two holes in the fork I1, or is otherwise held immovable therein, and is a freely turning t in link I8, where the length of the hole provides ample bearing surface. Similarly, pin 2l is xed relative to lever 20 and is a freely turning fit in the hole in link I8, where the bearing surface is ample. Pin 21, likewise, is xed relative to lever 20 and is a freely turning and sliding t in the two holes in Segments 23 and 24, which provide ample bearing surfaces. Pin 28 is xed with respect to segment 23, but slides freely in the hole in segment 26. Similarly, pin 29 is immovable relative to segment 24 and slides freely in the hole in segment 25.

All of the joints between the parts which consist of the five small, round pins I9, 2l, 21, 28 and 29, together with the holes into which they fit, are not only extremely economical to produce, relative to other forms of suitable joints, but they reduce lost motion and friction to a minimum, so that the hand of the operator can feel the stretching of the metal of the ring with the least possible distraction, almost as if his hand were in direct contact with the ring itself.

In some other ring stretchers of the general type under discussion, as well as in some other devices in which expanding arbors are incorporated, the split arbor is supported and restrained against endwise motion by the fixed framework of the device, while a separate, internal, wedgelike part is forced endwise between the segments of the split arbor so as to spread them apart. In my invention, by contrast, the central wedge also serves as the sole support and vertical guide for the split arbor. One simple, stationary part, the stem I5, performs all three of these important functions, supporting, guiding and wedging. Both of the necessary motions; endwise-and-radial (or expansional), are, in my device', imparted to the ring stretcher which require'sany but tli'e-Jno'std ordinary toolsland-processes-:fo'riitsmanufacture. Theiouter-surface'of-this arbor'f-m-ust bef'exceptionallyhardand Adurable solasl to1withstand :the severe local pressure strains to which it is subjected during the stretching of rings, and not become grooved or roughened thereby.

By far the most suitable material for this arbor, especially from the standpoint of economy, is steel which has been hardened by heat treatment, although other materials or combinations of materials which would function satisfactorily could no doubt -be found, Unfortunately, any such heat treatment tends to warp steel parts, espe-I cially when they are relatively long and thin and non-symmetrical in cross section, as are the arbor segments 23, 24, 25 and 26. To serve their purpose Properly, these segments must be reasonably straight. Assume, for instance, that one of the segments is slightly bowed, so that it comes into contact with the central stem I 5 only near its two ends, leaving .a space between the segment and the stem along the middle portion of the arbor, and that a medium sized ring is dropped onto the arbor and comes to rest in contact with the arbor segments opposite the place where one of the segments fails to make proper contact with the stem l5. Then, when the lever is depressed, so as to expand the arbor, the bowed segment will yield elastically to the pressure and be straightened out against the side of the stem, after which the normal stretching action against the ring begins to occur. This lost motion, due to the yielding of the bowed segment, would not only Waste a part of the stroke, but the hand of the operator would `be unable to feel sensitively how much force was being applied to the ring.

In some cases, similar steel parts which have thus become warped during their heat-treatment, have been straightened by mechanical means, but such processes are, at best, slow and uncertain. When similar heat-treated steel parts are used in devices such ,as precision tools, where the parts must be finished to a very high degree of accuracy, it is customary to grind all critical surfaces after the heat treatment. Such grinding operations for the tapered arbor segments 23, 24, and 26, particularly for the conical inner surfaces of these parts, would be prohibitively expensive in the case of a ring stretcher to be sold in large numbers at a low price.

To avoid these diculties in the manufacture of these arbor segments, I proceed as follows: Beginning with a square steel bar having the same cross sectional size as the square portion of the complete arbor 22 which fits between the two vertical anges of the lever 20, I rst drill and ream the three transverse holes into which the pins 2l, 28 and 29 are later fitted; drill and ream the longitudinal, perform the various external turning operations; and as a final machining operation, as shown in Fig. 4, cut four narrow, longitudinal slots 33, 33 which almost but not quite separate the arbor into its four segments, the latter being still joined to each other by thin bridges of metal 34, 34, extending from end to end of the arbor.

The next step in the manufacture of the arbor tapered, central hole;

is'a L the hardening yi-:hear

getlier, frestrain eaclrio'ther from-warping. i After undergoing-exposure ltoi an lextremely' low tem'- I perature, Lwhich!relievesllocal tensionsfin the steel, 'set-1 upf-by"l theo hardening vtreatment, the fourvse'gmentsare Icracked 1apartandffthe1rough ed'gesgrepresentinglthe i-teinporarybridgesl 34,-"

34, are1lremovedibyfa `quick, simple-'grinding operation-.1 The-slight-fresidual warpage resulting from this method of treatment is negligible.

It is desirable-that the width of the slots 33. 33o' be equal to"-y the maximum-:diametricalf expansion of the arbor. At stroke, when the arbor is fully collapsed, it is not truly circular in cross section; each two adjacent, curved, outer surfaces meet at a slight angle, as best seen in Fig. 5. At the termination of the stroke, when the arbor has been expanded to its maximum size, it has assumed as nearly as possible a truly circular form in cross section, as best seen in Fig. 4, which desirable shape is shared by any ring which has just been stretched.

In order to make clear this diil'erence in shape under the two conditions, the width of the slot, as indicated in Figure 4, and the equivalent magnitude of the collapsing movement, as indicated in Fig. 5, have been greatly exaggerated; in actuality, the slots are hardly wide enough to produce any perceptible deviation from a truly circular form even when the arbor is fully collapsed. It is nevertheless desirable that the maximum deviation from a truly circular form occur when the arbor is collapsed, instead of when it is fully expanded, at which time it impresses its shape on the rings.

While I have illustrated and described with particularity only the one embodiment of each novel feature of my invention, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements that come within the definitions of the invention constituting the appended claims.

I claim:

l. A nger ring stretcher comprising a base, a stationary tapered stem rising from the base, an expansible tapered arbor surrounding the stem and divided lengthwise into four equal segments, spring means on the arbor to cause the arbor to be yieldingly held in a contracted condition, a pin extending transversely through two segments of the arbor toward the lower end, at right angles to the plane of division between the latter segments, and having a sliding fit in at least one of such segments, an operating lever having portions lying on opposite sides of the lower end of the arbor and lixed to the ends of the aforesaid pin, and two additional pins on opposite sides of and p arallel to said plane, each of the latter pins passing through the two arbor segments on the corresponding side of said plane and being slidable in at least one of the latter segments.

2. A finger ring stretcher comprising a base, a stationary tapered stem mounted on and rising from the base, an expansible tapered arbor surrounding and slidable lengthwise of the stem, a l

long, wide lever containing near one end a large opening through which the arbor freely extends, an upright link hinged to the base below the said end of the lever, a hingeconnection between the upper end of the link and the lever, a hinge pin extending through two of the segthe; 'beginning of i the`y ments at the lower end of the arbor and xed' at its ends to the lever atopposite sides ofthe opening in the latter, the axis of said pinbeing parallel to the axes of the hinges at the two ends oi* the link, and additional pins each passing transversely through two arbor segments `and slidable in at least one of the latter to form with the hinge pin tie means to hold the arbor segments against relative lengthwise movements.,

EARLE G. HENRY.

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

8 UNITED STATES PATENTS Number Number Name Date Hughes May 31, 1927 Pratt June 9, 1942 FOREIGN PATENTS Country Date Germany Aug. 29, 1900 Germany Dec. 14, 1901 Germany May 28, 1926

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