US2634452A - Last thimble - Google Patents

Description

P 1953 w. J. RIPLEY ,634,452

LAST THIMBLE Filed March 3, 1950 Patented Apr. 14, 1953 LAST THIMBLE William J. Ripley, Marlboro, Mass, assignor to Koehler Manufacturing Company, Marlboro, Mass., a corporation of Massachusetts Application March 3, 1950, Serial No. 147,539

1 Claim.

This invention relates to an improved last thimble such as is customarily used in the cone of a last to receive the last spindle, and more particularly the invention is concerned with spinning a last thimble from a tubular body.

Last thimbles are now manufactured from flat sheet metal by the punch press process where they are drawn to shape and size by relatively expensive and time consuming annealing operations; also from solid bar metal by the screw machine process wherein the stock is drilled to shape and size, requiring excess amounts of stock and labor. Attempts have also been made to form a thimble by spinning one end of a tubular body closed, but in all of these attempts it has been found necessary to employ some kind of heat which greatly detracts from the value of such operations and has discouraged their use.

The present invention deals with the problem indicated and seeks to devise a method of spinning tubular bodies to form a closed end thimble which is characterized by a suitably heavy and Wear-resistant end wall and shoulder construction and which can be manufactured more cheaply and quickly than presently manufactured last thimbles. It is also an object of the invention to provide a method of spinning in which the use of heat is avoided and breaking of edges of the tubular stock is prevented.

These and other objects and novel features will be more fully understood and appreciated from the following description of a preferred embodiment of the invention selected for purposes of illustration and shown in the accompanying drawings, in which:

Fig. 1 is an end elevational view of a tubular member employed in making the last thimble of the invention;

Fig. 2 is a side elevational view of a length of the tubing illustrated in Fig. 1;

Fig. 3 is an assembly view indicating the tubular member of Fig. 2 supported in a chuck with a spinning tool arranged in juxtaposition thereto;

Fig. 4 is another elevational View of the tubular stock and spinning tool assembly and further indicating the spinning process in a partly completed state;

Fig. 5 is a cross-sectional view further illustrating the tubular stock at the point in its preparation resulting from use of the spinning tool shown in Fig. 4;

Fig. 6 illustrates another spinning tool in engagement with the tubular member illustrative of the step of finally closing one end of the latter member; and

Fig. '7 is a longitudinal cross-sectional view showing the completely spun closed-in construction.

According to the invention I provide for an at tenuated spinning movement in which working or drawing of the metal takes place along a reversely curved path of contact made possible by a novel spinning tool shape.

In the structure shown in the drawings, numeral H] denotes a tubular body preferably composed of a substance such as steel of suitable hardness, and chosen of a length designed to provide a conventional shoe last thimble. The tubular member Ill in accordance with the invention is supported in a rotating work-holding member or chuck [2, as shown in Fig. 3, in position to be engaged by a spinning tool, such as that shown at it, also mounted for rotation and indicated in Fig. 3. The spinning tool is formed with a reversely curved shoulder l6 which terminates in a reduced end portion I8. The curve which defines the shoulder portion and reduced end is so chosen that its radius extends only part way of the radius of the tubular stock It].

In accordance with the invention, a reversely curved spinning tool of the character described and preferably of a diameter much longer than that of tubular section I0, is brought into engagement with the latter element in such relative position that the edges 20 of the left-hand edge of the tubular member ID, as viewed in Fig. 3, project beyond the shoulder portion N5 of the tool and the latter portion bears against intermediate portions of the tube periphery. As the spinning operation progresses the shape of the reversely curved shoulder i6 is duplicated on intermediate portions of the tubular member l0 and simultaneously edge portions 20 of the tubular member are brought into converging relation without actually having any direct contact of the spinning tool thereagainst, and there thus results a spinning operation in which a rollingover of the edge of the tubular stock takes place with an inner tip 22 gradually being formed centrally of the longitudinal axis of the tube, as is more clearly shown in Figs. 4 and 5. A series of tools of progressively smaller sizes may be utilized in developing the tip formation.

It will be seen that the edges 20 throughout this part of the spinning operation receive little direct contact such as would tend to break or crack these edges apart, as is the case in conventional types of spinning operations. Also, this reversely curved spinning tool construction permits a forming and drawing of the tubular stock to take place gradually along a. considerable area adjacent to the shoulders. reinforcing is found to materially increase the of the tube periphery without the aid of heating, such as is normally resorted to in spinning with conventional type spinning tools.

When the metal is drawn to form the tip 22 in a greatly reduced form, a final spinning operation may be oarriedout employing a spinning tool 24, such asthat illustrated in Fig. 6. "This 'tool is provided with a flat end face 25 which can, at this time, be brought to bear against the reduced tubular portion 22 to contact and flatten the portion into a solid end wall 28, as shown in Fig. 7.

I have found that in thus "cold' spinning the tubular body I may efiect a've'ry' desired'hardening of the metal throughout the region which extends from the closed bottom wall upwardly along the shouldered portions and then wellbeyond the shoulders into the intermediate -portions ogf the peripheralwall of the tube. This extended'regionof hardeningl find to be im- "portant; both in the respect that the work hardness of the metal is materially increased by -the coldspinning at the bottom section of the thimble and the shouldersyand' also in the respect'that substantially increased 'work' hardness is provided for the peripheral wall portions just'above the shoulders. As a result, I am enabled to pro d'uce' a'thimbIe' of an exceptionally heavy durable end walla'nd"shoulderponstruction and, inaddition, I impart a pronounced reinforcing at the regionof the' w'all periphery lying immediately The effect of this life of" the thimble and to greatly increase its resistance to shock and wear. As an instance of the relative changeof hardening from" the cold spinning, there'may be cited in one tubular 1 body, before spinning, a Rockwell hardness of B45 to 48, and after spinning there'was'produced a Rockwell hardness; at the shoulders of the tubular body'of fromB69 to '70 and atthe shouldered portion, and peripheral body "portions "immediatelyadjacent the circumferentially center of the bottom of the spun tube a Rockwell hardness of from B to 62.

I have further found that by practicing a. method of cold spinning along a reversely curved path of contact, I may provide for substantial "savings in labor andl-material withthe result that a less expensiveilastttithimble may be produced. No breaking of the edges is caused to take place and no undesirable heating effects occur. 'azidesirable, efficient, and economical method of It will thus be seen that I have provided forming last thimbles, and have imparted de- "sirable'and"novel characteristics to the thimble body; produced by? this method.

Having thus described my invention, what I desire to claim: as new is:

-A-shoe last thimble comprising a tubular body having a closed end wall and a circumferentially shouldered portion extending upwardly there- 'from'and-mergingwith said body; said endwall,

shouldered portion being shaped by cold spinning to "provide" a'work hardness of said parts 25 tions of the thimble.

appreciably greater than that. ,of'remaining por- WILLIAM J .RIPLEY.

"References Citd'in'thefile of this patent

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