US3034160A - Shoemakers' lasts - Google Patents

Description

May 15, 1962 1.. D. RAYMOND SHOEMAKERS LASTS Filed une 10, 1960 INVENTOR D. RAYMOND LORENZO Unite 4 Claims. (Cl. 12-.136)

This invention relates to shoemakers lasts.

In the normal process of manufacturing shoes with leather soles, as distinguished from those having vulcanized soles, the last is generally constructed of wood and is so designed that the heel portion may be pivoted on the fore part portion thus causing a shrinking or decrease in the overall length so that the last may be removed from the shoe which has been formed around it.

Such prior types of last have usually been made of a single piece of hard and fine grained wood and have generally been divided, for example by a band-saw or similar tool, into two portions which are pivoted to allow such relative movement as is necessary to permit withdrawal of the last from the completed shoe.

Prior types of last have generally achieved such pivoting motion by employing one or more metal links retained at or adjacent their extremities by a plurality of pins, the links and associated pins being so disposed that the relative rotation of the heel and fore part portions will result in a general longitudinal contraction of the last as a whole.

Blocks from which lasts are made contain a substantial excess of wood so that a variety of heights of heels and widths of fittings may be formed from each block. Usually one particular length of block will provide only for a limited number of sizes, there being four or five blocks required to cover the full range of chlidrens, Womens, and mens lasts.

The comparatively large volume. of the blocks hitherto generally found necessary presents difliculties in drying the wood to a moisture contentof the required un formity or homogeneity.

Thus in the past diiiiculty has often been experienced in obtaining lasts, particularly when cut from the inner portion of the block, which will not deform by changing shape in excess of prescribed limits, due to absorption of atmospheric moisture.

Furthermore, it has hitherto been generally found that unless the position of the pins associated with the links mutually retaining the heel and tore part portions is closely controlled, difiiculty is experienced in eliecting the pivoting movement necessary prior to removal of the last, and an attempt to do so may cause a breakage in the wood, especially in the region of the pins and links,

States Patent ice thus resulting in a high percentage of reject lasts and hence a substantial wastage of material. Should the pins however be too far apart, the assembly comprising the fore part and heel portions will be excessively loose causing inadequate support of the shoe during processing operations.

The primary object of this invention is to provide a last which is readily adaptable to mass production, and which will permit a similar cross section of timber to be used for the heel and fore part sections and which will enable reduced stocks of last blocks to be held as a standard timber section to be used for both the heel and tore part sections.

Another object is to provide a last which will allow a greater degree of mechanical precision of thcportions in the rough state by machines being more readily capable of gripping the regularly shaped wood sections.

Further objects of the present invention are to reduce the problem of drying and also the cost and time of 3,034,160 Patented May 15, 1962 manufacture by having less timber to remove in the roughing and finishing operations.

The above and other objects and advantages of the invention will become apparent hereinafter.

Accordingly the present invention provides an improved last comprising a wooden fore part, a wooden heel part and two intermediate portions, moulded from plastic material, which are secured at their remote ends to said fore part and said heel part respectively, and are interconnected at their facing ends to enable the last to be broken preparatory to removal of a lasted shoe therefrom.

It is preferred that the wooden fore part and the wooden heel part have tongues or like portions projecting rearwardly and forwardly, respectively, the intermediate portions being moulded so as to fill the gaps between the tongues and thus bond the intermediate portions to their respective wooden parts. This embodiment thus provides a large interface between the heel and fore parts and their associated intermediate portions, and hence a large bonding surface, whose area depends upon the number and depth of the tongues.

The present invention further discloses a method of producing a last, comprising moulding the two intermediate portions from plastic material, adhesively mounting each said portion on a wooden block, linking the plastic portions so as to allow limited relative movement therebetween, and shaping the blocks and their associated plastic portions into a last with one block forming a heel part and the other, a fore part, the extent of said relative movement being sufiicient to allow for breaking the last.

By breaking the last, is meant causing such relative movement of its component parts from their operative or unbroken position, as is necessary to withdraw a lasted shoe from the last. Such movement may be substantially translational, using, for example, a planar interface between the intermediate portions, or may involve a relative rotation between the components, the latter being achieved when a curved interface is employed. In any event it is highly desirable to provide a toggle action between the operative and inoperative positions, that is, an action such that although the last is stable in either position, a substantial amount of force is required to break or unbreak it.

The pivot portions may be moulded to close tolerances thereby permitting a greater control over the tension mut-ually retaining the heel and fore part sections.

But in order that the invention may be better under-- forwardly extending tongues 11 spaced by intervening gaps 12. Two intermediate portions 13, 14 associated respectively with parts 7 and 10 are plastic mouldings, the plastic material filling the gaps between the tongues so as to bond the intermediate portions 13, 14 to their respective wooden parts 7, 10

Each intermediate plastic portion has a cavity suitably located to accommodate link means for interconnecting them. The cavity, in the drawing visible in the forward portion only, advantageously comprises a transverse bore 15 communicating with a longitudinal recess 16, the recesses having apertures oppositely disposed in the facing ends 17, 18 of the intermediate portions, and the articulative means comprising'a link 19' perforated adjacent its action between the operative and broken positions of the last.

The last is advantageously provided with a metal, fibre or leather strip 28 located on an upper surface of the heel part It) and corresponding intermediate portion 14, this strip forming a strengthening base for a thimbl'e-receivingshaft 29. When it is desired to break or unbreak the last a thirnble may thus be readily inserted to retain the heel part in a substantially fixed position, while the fore part is moved relatively to it.

Referring now in particular to FIGURES 2 and 3, a preferred method of forming a last comprises shaping end parts 20,21 of two woodenblocks into a plurality of tongues 22, 23 respectively, the projections being spaced by intervening gaps 24, 25 respectively. Moulds (not shown) having appropriate moulding facesare mounted 1 so as to overlie the shaped end parts, and plastic material is compressively injected into. each mould so that the material fills the gaps 24, 25 to provide a gripping relationship between the moulding and the associated block. Such moulding will in almost every case involve a deformation of the tongues in the respective wooden block,

- and the irregularities introduced materially assist the bonding adhesion between the molding'and the corresponding block. a t

Each mould has provision for'leaving in the resultant moulding a cavity comprising a transverse bore communicating with a longitudinal recess (indicated by the dotted lines, FIGS. 4 and 5), to accommodate link means for interconnection of the plastic portions. The moulded face of the mould is such that the resultant plastic mouldings will each be provided with a bearing surface, e.g, 26', shaped complementarily to a bearing surface 27 on the other moulding. so that during the relative movement of the p rtions connected by the-link means, the complementary bearingjsurfaces 26, 27 remain substantiallyin contact.

When the plastic material has set to the required degree the moulds are removed and the link means engaged whereby the plastic portions together with their associated blocks are connected as shown in FIGURE 6.

It may be desirable to mould one of the plastic portions With its pin already in position passing through the link. In this case the plastic portions may be connected simply byplacing'these portions adjacent one another with their complementary surfaces 26,27 in engagement and the link positioned in both recesses. To complete the connection it now only. remains to insert the pin in the other intermediate portion so as to pass through the vacant perforation in the link 19. The structure shown in FIGURE 6 is then shaped into the desired form of last with one block, for example 21, forming the fore part 7 and the-other 20, the heel part 10.

It will'be apparent from the above that the present invention will allow similar cross sections of timber to be used for the heel and fore part sections thus elfecting a substantial saving in time.

,The'invention will also enable reduced stocks of last blocks to be used as the standard section of timber employed for both heel and fore part sections and will permit of an improved degree of mechanical precision of the portions in the rough state by machines being more readily capable of gripping the timber sections. Furthermore, the number of machine operations hitherto required in forming the pivot portion, and also the problems associated with drying are materially reduced.

If desired each intermediate portion and its corresponding wooden part may be formed independently. To this end, the plastic portions are formed in. moulds which are advantageously. shaped so as to provide in the resulting moulding, in addition to the bearingsurface and the cavity accommodating the link means, a plurality of tongues and intervening gaps. Thus, the moulds may have a configuration such as shown by the member overlying end part in FIGURE 4. The blocks destined to form the fore and heel parts in the last are shaped so as to provide on each a surface adapted to register with a complementary surface of the corresponding intermediate portion; for example, if the moulding has the tongue and groove configuration shown in FIGURE 4, then the complementary portion of the correspondingblock 20 is shaped such as shown in FIGURES 2 and 4. Each intermediate portion is then mounted on the relevant end part with their respective complementary surfaces in abutting relationship. Such mounting is preferably efiected by application of an adhesive to the surfaces. The intermediate portions may then be connected, for exampleby the link means described above, and the structure comprising the connected portions and blocks shaped into the desired form of last, one block forming a forepart and the other, a 'heel part, the extent of relative movement between each intermediate portion and block being suflicient to allow for breaking the last, as previously described.

In addition, those portions ofthe-last whose shape must be precisely controlled may be readily massproduced and the overall cost of manufacture is substantially redu-ced, since there is now less timber to be removed, in the roughing and finishing operations.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An improved last comprising a wooden fore part, a wooden heel part and two intermediate portions of plastic material secured at their remote ends to said fore part and said heel part respectively, said intermediate portions being provided with articulative means interconnecting the portions at their facing ends to enable the last to be broken preparatory to removal of a lasted shoe there- I ing a transverse bore communicating with a longitudinal recess, the recesses having apertures oppositely disposed in the facing ends of the intermediate portions, the said link being seated in the longitudinal recess and bridging said portions, and a pin fitted in each bore and passing through a link perforation, the arrangement being such that the articulative means affords a toggle action between the operative and broken positions of the last.

4. An improved last comprising a wooden fore'part having tongues projecting rearwardly therefrom and forming intervening gaps, a wooden heel part having tongues projecting forwardly therefrom'and forming intervening gaps, and two intermediate portions of plastic material formed so that parts thereof fill the gaps between the projecting tongues of the fore part and the heel part and bond the intermediate portions to the-fore part and the heel part, said intermediate portions provided with articulative means interconnecting the portions at their facing ends to enable the last to be broken preparatory to re- .moval of a lasted shoe therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 2,113,661 Lucas Apr. 12, 1938 2,260,568 Goodman et a1. Oct. 28, 19-4 1 2,330,260 Baxter Sept. 28, 1943 2,716,431 Clausing Aug. 30, 1955 2,850,752 Leahy et al. Sept. 9, 1958

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