US2188414A - Hinged last - Google Patents

Description

Patented Jan. 30, 1940 UNITED STATES PATENT oFFlcE HINGED LAST Alexander W. McNeill, Lynn, Mass.

Application May 11, 1939, Serial No. 273,022

5 Claims.- (Cl. 12-136) This invention relates to hinged lasts and conslsts in an improved link or hinge member constructed to perform the usual functions of keeping the toe and heel parts of the last together 5 and of maintaining the last in either open or closed position.

The most important object of my invention is to provide a more durable and eillcient last by employing a novel link which requires the 10 minimum amount of Working space in the interior of the last parts and which securely holds the parts together against relative longitudinal displacement.

Many lasts as heretofore lconstructed have been 15 unsatisfactory from the standpoint of durability because the extreme pressures encountered in the levelling, sole pressing, and cement sole attaching operations tend to break down the lasts in the areas where the parts have been weakl ened to provide working space for the hinge members which holds the last parts together. Furthermore the .design of many links now in use is such that the links elongate and the parts of the last are permitted to separate to an ob- 35 jectionable extent under pressures ordinarily encountered in shoemaking operations.

An important advantage of my invention resides in the fact that my novel link may yield Without danger of breaking and without per- 30 marient elongation and does not permit separation of the parts of the last except under extraordinary or abnormal pressures Where a slight separation is desirable because it saves the wood and prevents breaking. l

35 To accomplish the objects and secure the advantages outlined above I employ a link com- Drising one or more thin dat metal stampings formed as closed bodies wherein one side member is curved more than the other side member,

vo an internal arcuate slot separating the sides of the link and defining their shape. The ends of the slot are engaged by the usual anchor pins passing transversely through the heel and toe parts of the last. 'Ihe anchor pins are so located that in their normal positions a line connecting their centers falls to one side of the axis of rotation of the two parts of the last, it being understood that the parts of the last are provided with interfltting curved surfaces to pro- 50 vide for relative rotation of the heel and toe parts about a fixed axis. As one part of the last is rotated about this axis the link is forced to lengthen out in toggle action as the center line of the two anchor pins passes across the 55 axis of rotation. After the center linehas passed the axis of rotation tension on the link is relieved, although in closed position of the last the link is maintained under tension so that the two parts are held firmly in operative position. As the side of the link with the greater curve 5 fiexes, it is checked and guided by the relatively stiffer side with the lesser curve.

These and other features and advantages of the invention will best be understood and appreciatedfrom the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which:

Fig. 1 is a view in side elevation of a last in closed position with portions broken away to expose the link construction,

Fig. 2 is a view in cross-section along the line 2-2 of Fig. 1,

Fig. 3 is a view in side elevation of a link constructed according to my invention and showing in dotted lines its action under longitudinal tension,

Figs. 4 and 5 are views in cross-section through the center of a last showing the parts in collapsed and intermediate position respectively.

As shown in Fig. 1, the last of my invention includes a heel part I0 provided with the usual comb plate I1 and a metal plate I3 secured to the last bottom by screws I9 and bynails 23. The heel part I0 is provided at its forward end 30 With a hinge projection II of circular contour which extends transversely across the front of the heel part. The last alsov includes a toe part I4 provided at its rear end with a transverse concave depression into which the projection II fits closely so that the parts I0 and I4 may be relatively rotated upon the line I2 as an axis.

The heel part II is bored to receive an anchor pin I5 which is parallel to the line I2, and o the toe part u is provided with a simuar anchor 4 pin I8. The pins I5 and I6 are so located that when the last is collapsed as shown in Fig. 4 or closed as shown in Fig. 1, a line connecting their centers falls to one side or the other of 5 the axis of rotation represented by the line I2.

The anchor pins I5 and I6 are connected by one or more links 20 each of which is a plate or stamping of spring steel or other tough resilient metal formed as a closed body having 60 relatively long spaced side members or glands and a centrally located arcuate slot provided with enlarged ends to fit the anchor pins I5 and I6. The two side members of the link are approximately of the same width and merge at their ends into the rounded ends of the body of the link. As shown in Fig. 3, the lower side member of the link 2B has a pronounced concave curve, and an upper side member which is almost straight or slightly convex. Fig. 2 shows how a plurality of links 20 may be used in a last if desired. It is desirable to use a plurality of relatively thin links rather than a single thick link because of the convenience with which the thinner links may be stamped from sheet steel, but the employment of a single link is within the scope of my invention.

When the last is closed as illustrated in Fig. 1 the line connecting the centers of the anchor pins falls slightly below the axis I2 of rotation of the parts of the last. In intermediate position, as shown in Fig. 5. the center line of the anchor pins intersects the axis I2, and in collapsed position the center line is above the axis I2. The distance between the anchor pins I5 and I6 is the same except when they are in alignment with the axis of rotation of the last parts. However, when the axis I2 intersects the center line of the anchor pins, the distance between the pins is increased, and the links 20 must elongate in order to permit such movement of the last parts. The last is thus locked in closed position and can only be broken when the toe portion is moving upwardly with sumcient force to elongate the link in carrying over the dead center.

It will be apparent from an inspection of Fig. 3 that the lower side member of the link is curved so that it can be flexed and thereby lengthened, but the substantially straight upper side member acts as a check and makes it harder to ex the link as a whole. The upper side member acts as a relatively stiff beam when the lower side member is straightened in flexing and limits the ends of the link to outward movement as shown in dotted lines in Fig. 3. The

upper member itself may be very slightly deilected in this action. The resilient tension thus created is such that the link 20 will snap the last either to closed or collapsed position when the parts are once forced past the dead center.

It is apparent from Fig. 2 that the use of links constructed according to my invention requires that only a narrow slot be cut into the parts of the last. Since a minimum amount of wood is removed, the last is not seriously weakened as is the case where more bulky links are used. Furthermore the slot in the heel part does not interfere with the screws I9 used to secure the metal heel plate I3 to the last bottom, a distinct advantage in the manufacture of lasts. As shown in Fig. 1 the butt of the toe part below the circle cut is perfectly solid and not interrupted to provide working space for the link 20.

The links are so dimensioned that the anchor pins I5 and I6 exert considerable pull tending at all times to distort the link 2l) and to force the parts of the last together, a pull which resists the stresses ordinarily encountered in shoemaking operations. If excessive and extraordinary pressure is applied, the parts will separate slightly and yield so that there is little danger of breaking the wood of the last. l

It will be understood that the degree of curvature of the sides of the link is not critical, but that the one side must be curved more than the other so that it will flex more readily than the other if the desired advantages are to be secured. In links heretofore used it has been necessary to leave clearances so'that the parts f the last could be rotated, with the result that when the last was in either normal position, the parts were loosely held together. 'I'he link of my invention, due to its self-contained spring action, holds the parts of the last tightly together at all times and in all relative positions of the Parts of the last.

It will beunderstood that the links 20 are slightly elongated at all times when the last is closed so that the parts arev then held closely 10 together. The links are further elongated as the parts of the last are rotated upon each other in passing over the dead center position.

I contemplate the use of either one or a plurality of links in a last, according to the size and weight of the last. Where a single link is used it may conveniently be formed of thicker metal than would be employed where a plurality of links are used.

The foregoing description relates to but one zo expression of the spirit of my invention and will serve as an illustration of a structure in which my invention can be visualized. However, my invention is limited neither by the materials mentioned in the description nor by the conguration of the elements shown in the drawing, since there are many possible embodiments of my invention in which the shapes and materials 0f the elements and their relative locations may differ considerably from those specifically disclosed above. For example, the links may be inverted and still function equally as well as in the position shown in the drawing. The determination of the scope of my invention by means of the appended claims should be carried out with this paragraph in mind.

Having thus described my invention, what l' claim as new and desire to secure by Letters Patent of the United States is:

1. An improved last comprising heel and toe 40 parts having intertting curved surfaces shaped to permit relative rotation of the parts about a xed axis, a last hinge link including a closed exible body having continuous side members curved unequally and separated by a curved slot, a and a pair of anchor pins disposed transversely through the toe and heel parts respectively and passing through said closed body and so located that in their normal position a 'line passing through their centers falls to one side of the axis m of rotation of the parts of the last.

2. A last hinge comprising a single piece of sheet steel provided with a centrally located longitudinally curved slot having enlarged ends, the piece being shaped so that the slot divides its major portion into a substantially straight side member and a ilexible curved side member.

3. An improved last comprising toe and heel parts having curved intertting surfaces to permit relative rotation of the parts, a link including a closed body having side members of unequal curvature separated throughout their length by a curved slot, and anchor pins disposed in said toe and heel parts and maintain ing said link under yielding tension, whereby Said link holds said parts firmly together.

4. An improved last comprising toe and heel parts having curved intertting surfaces to permit relative rotation of the parts, a plurality of links each of which comprises a closed body of sheet steel having side members of unequal curvature separated throughout their length by a curved slot, and anchor pins disposed in said toe and heel parts for maintaining said links in elongated condition to create a yielding tension holding said toe and heel parts rmly tially equal width, one of said side members betogether. ing slightly curved and the other having a; pro- 5. A last link comprising a at sheet metal nounced curvature whereby the later is rendered body, resilient in character, having rounded ends substantially more exible under tension than 5 and a. curved longitudinal slot dening in the the less curved side member. 5

body of the link two side members of substan- ALEXANDER W. McNEILL.

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