Multi-part last that can be disassembled in a gentle manner

Abstract

A multi-part last that can be disassembled in a gently manner, comprising a front portion (20), a rear portion (30), and a wedge portion (40), wherein the bottom of the front portion has a rearwardly extending projection (21), the bottom of which forms part of the bottom of the last (10), which ends in a rear support (22) having an end forming a first circular arch (23), and the front portion is partially open at the top, has a partially open and partially closed cavity (27) shaped in the form of a second circular arc (26), and the lower portion of the rear part has a front face resting on the circular arc of the rear support, and in addition the rear part has a locking projection (34) introduced into and terminating in said cavity, the front and upper faces of which are curved in said second circular arc, and a part of the last (10), when assembled, rests against the concave inner wall of the cavity, which is curved in accordance with the second circular arc, and the wedge part has a shape that fits in a cavity formed between sections (31, 32) forming the frontal surface of the rear part and sloping downwards from above, and sloping lower and upper wedge sections (28, 29), of the front part, wherein said circular arcs are concentric with each other and have their centers (O) at or below the line of the bottom of the last, and the assembled last can be removed from the front part by partial rotation of the rear part about the center after removal of the wedge.

Description

[0001] Multi-part last that can be disassembled in a gentle manner

[0002] The object of the invention is a multi-part last that can be disassembled in a gentle manner, comprising a front part, a rear part and a wedge part that interconnect the front and rear parts, wherein in assembled condition the rear part is form-fittingly connected to the front part and the bottom of the front and rear parts are the continuation of each-other and form together the bottom of the last.

[0003] For centuries, shoes have been made using a last, which is best defined in Wikipedia (https: / / en.wikipedia.org / wiki / Last) as: "a last is a mechanical form shaped like a human foot. It is used by shoemakers and cordwainers in the manufacture and repair of shoes". The material of the last is traditionally wood (hornbeam, steamed beech), polyethylene, metal (steel, aluminum). It is also used in the repair of shoes. It is the traditional tool of the shoemaker, bootmaker and, in the past, of the stitcher, the uppers maker. In addition to the one-piece lasts, shoemakers also use extendable, hinged and wedge tools.

[0004] EP 1 916 919 Bl describes a multi-piece last with an inner cavity, on the outer surface of which adjustment members can be placed in suitable positions, the shape of which follows the shape of different protrusions and swellings of the foot concerned, thus allowing the production of shoes with individual sizes. The special preparation and fitting of these protrusions constitute an additional task, and owing to the presence of the protrusions the removal of the last from the finished shoe requires the partial stretching or deformation of the upper of the shoe, which may influence the exact size of the shoe.

[0005] The publication US 2012 / 0266497 Al deals in detail with the anatomy of the foot and the design of a comfortable shoe to fit it, where the multi-piece last used was considered important to maintain the correct angles of the different parts of the last in relation to each other. This publication does not deal with the assembly and disassembly of the parts of the multi-piece last, nor with the tension forces acting on the freshly made upper part of the shoe during the removal of the last.

[0006] US 5,718,013 deals with the ideal shape of the last and describes the conditions that must be considered when designing the last. The publication does not address the question of how the parts of the last fit together and how they can be removed from the shoe after it has been made.

[0007] Shoes can be made both in large series and made to measure. The use of last is indispensable and the shape of the last is specified either in a universal way to suit the associated size or in variations of a size, and the user chooses the most comfortable one from the range available. In the case of customized requirements, the shape of the foot is mapped using modern tools and stored in a computer, and the customized last can be made by 3D printing. 3D printing has certain technical requirements, for example, it is difficult or impossible to create internal cavities using this process. The design of internal cavities is not straightforward even with conventional technologies, and for reducing manufacturing costs, it is advisable to use solutions that do not contain cavities or only such ones that can be easily manufactured.

[0008] The lasts are most often made up of several parts, which comprise a front part and a rear part connected by a hinge system, or a wedge part that extends in between them to connect the other two parts and unite them in a rigid way. The upper part of the shoe is placed on the surface of the stiffened last, and it is the outer surface of the last which, by means of a suitable stretching technique, determines the shape and the internal cavity of the upper part of the shoe. To remove the last, it is necessary to pull it out by displacing the parts of the last or by tilting the wedge, which is usually made possible by forcibly turning the back and front parts. When the rear part is turned, the last becomes longer and this temporary increases the size and further stretches, forces and distorts the inside of the upper of the shoe. In addition to the fact that some upper parts resist such an expansion, which makes the removal of the last more difficult, the forced stretching distorts the precisely designed interior of the shoe, reducing thereby its quality.

[0009] The object of the invention is to create a multi-part last, and during removal of the last from the shoe, the upper will not be subjected to a distorting, tightening force. Such a disassembly is referred to as a gentle disassembly.

[0010] This object has been solved by creating a multi-part last that can be disassembled in a gentle manner, which has a connectable and separable front part, a rear part and a wedge connecting them, wherein the rear part is connected to the front part in a form-locking manner when assembled, and the bottoms of the front and rear parts are the continuation of each other and forming the bottom of the last, and according to the invention the bottom of the front part is a rearwardly extending projection, the bottom of which forms part of the bottom of the last, and this projection terminates in a rear support having a first end that extends in upward and forward direction and forms a circular arc. As used in this specification, the definition of 'circular arc' is understood in the section taken in the longitudinal vertical median plane of the shoe and in the intersecting planes parallel to it. Above said projection, the front part has a cavity partially open at the top and closed at the front by a second circular arc from above, and the front lower part of the rear part has a frontal surface resting and fitting against said first circular arc of the rear support, and in addition the rear part has a locking projection introduced into and terminating in said cavity, the front and upper surfaces of which are curved in said second circular arc and, in the assembled condition of the last, a front part of the locking projection rests against a concave inner wall of the cavity curved in correspondence with the second circular arc, said first and second circular arcs being concentric and their centers being at or below the line of the bottom, the wedge fits into the downwardly tapering wedge-shaped opening between the front and rear parts, and the assembled last can be removed from the front part by partial rotation of the rear part about its center after the removal of the wedge part.

[0011] In a preferred embodiment, the rear support has a support surface sloping forward and downwardly from the end of the first circular arch, forming the rear wall of the cavity, the support surface having a recess therein and a projection on the locking projection fitting into the recess.

[0012] It is advantageous for the fit if the bottom of the wedge has a curved bottom in the same arc as the second circular arc.

[0013] In a preferred embodiment, the frontal end face of the rear portion has downwardly sloping sections from above and the rear end face of the front portion has sloping lower and upper wedge sections, and the wedge part is fitted between these frontal end faces.

[0014] In a preferred embodiment, the upper portion of the front surface of the rear part is less inclined than the lower portion.

[0015] Similarly, it is preferable if the upper part of the rear surface of the front part is less sloping than the lower part.

[0016] The last according to the invention is suitable for the manufacture of custom-made shoes, especially orthopedic shoes, but can also be used for mass-produced shoes. Disassembly and reassembly of the resulting last is easy and does not require stretching of the upper part of the last.

[0017] The multi-part last according to the invention is described in more detail below, based on an exemplary embodiment threof, in which reference will be made to the accompanying drawing. In the drawing:

[0018] Fig. 1 shows the elevation sectional view of the last according to the invention in its basic position;

[0019] Fig. 2 shows the last of Fig.l in a partially disassembled position with the wedge part removed.

[0020] A last 10 shown in Fig. 1 has three main parts, which are front part 20, rear part 30 and wedge part 40. In accordance with the main purpose of their use, the outer mantle surface of the front part 20 and the back part 30 follows the shape of the upper of the shoe to be made, and more precisely these common outer mantle surfaces determine the shape of the upper. The actual shape and design of the upper are outside the scope of the present invention, which latter is constituted mainly how to realize the correct fitting of these parts and how to ensure a comfortable assembly and disassembly of these three parts.

[0021] The front part 20 represents the longest part of the last 10 and the rear portion thereof comprises a projection 21 at the bottom, nearly parallel to the base, and it continues with a thicker rear support 22 that has an arced rear surface forming a first circular arc 23 and has a frontal end support surface 24 that slopes in downward and forward direction towards the upper surface of the projection 21. Between the lower end of the support surface 24 and the upper surface of the projection 21 a rearwardly extending recess 25 may be formed. A second circular arc 26 extends upwardly and rearwardly from the forward end of the upper surface of the extension 21. A cavity 27 is thus formed at the rear portion of the first part 20 which is partially open at the top, the shape of which, as will be described later, essentially determines the insertion and removal of the three main parts. The machining of this cavity 27 does not present any technical difficulties, even when 3D printers are used. The rear surface of the first part 20 is formed, on the one hand, by a lower wedge section 28 which closes an acute angle with the rear end of the second circular arc 26, and thus rises obliquely forwards and upwards, and, on the other hand, by an upper wedge section 29 which is connected to the upper end of the first part 20 and rises almost vertically upwards.

[0022] The outer mantle of the rear part 30 comprises at its front a downwardly directed entry section 31, further down and slightly forward from there a wedge section 32, and a guiding arc 33 curved forward and downward at its lower end wherein the curvature of the guiding arc 33 is identical to that of the second circular arc 26 opposite to it. The guiding arc 33 is connected, through a slightly curved end portion to the bottom of a locking projection 34, which is shaped like a foot and formed in the front and lower portion of the rear part 30, and the rear lower end of the locking projection 34 follows the shape of said recess 25 and has a projection 35 which can be inserted in the recess 25 as shown in Fig. 1.

[0023] This arrangement is characterized by the fact that the center point O of the rear surface that has the shape of the first circular arc 23) is concentric with the first circular arc of the projection 21 of the first part 20, and this common center point O is in the bottom plane. This definition applies, of course, to the projection shown in the drawing, but along planes extending parallel to the plane of the drawing this curvature is a circular arc.

[0024] A wedge-shaped opening is formed between the front part 20 and the attached rear part 30, into which the wedge part 40 can be inserted from above. As shown in Figure 1, the profile of the wedge part 40 precisely fits in the entry section 31 and the wedge section 32 of the rear part 30 and in the lower and upper wedge sections 28 and 29 of the front part 20. At the bottom, the bottom of the wedge part 40 is curved following the curvature of the second circular arc 26 and therefore supports the upper guiding arc 33 of the locking projection 34. The illustrated position of the wedge part 40 can be fixed in several ways, but it is most preferred to appropriately choose the inclination of the boundary surfaces thereof so that the wedge part 40 get supported and held in place with little force. Removal can be accomplished with minimal tensioning of the upper fitted on the last 10, wherein the tension remains within the limits of the elasticity thereof. If one wished to avoid even this small amount of elastic tensioning, the wedge parts 40 can be interconnected at their lateral surfaces in locations outside the range covered by the upper.

[0025] It can be understood that in the basic state illustrated in Fig. 1, the three parts of the last 10 constitute a single rigid structure in which the wedge part 40 holds the front part 20 and the rear part 30 in this interconnected state, and the last 10 can be used for the shaping of the upper to follow its form.

[0026] Reference is made now to Fig. 2 which shows an intermediate position of the disassembly of the last 10. In Fig. 2, the wedge part 40 has already been removed by an upwardly directed pulling motion. The rear part 30 has been turned around the center O in the direction of arrow 41 by an angle a, but its position is still held by the connections along the first and second circular arcs 23 and 26, but the projection 35 has already moved out of the recess 25. Figure 2 shows that, in the empty space formed after the wedge part 40 has been removed, the rear part 30 can still be turned further about the center point O, and the length of the locking projection 34 allows the rear part 30 to be pulled vertically out of the cavity 27 before the extreme position of the turning.

[0027] In Fig. 2, displacement path 37 of a rearmost point 36 of the rear part 30 has been shown around the center point O of the circular arc. The observation of this path 37 is significant because the heel part of the upper of the shoe to be made overlies the rear part 30, and the disassembly of the last 10 can be made without stressing the upper if the direction of the path of the disassembly has only forward component from the initial position when the heel part of the shoe is not stressed from the inside to the rear when the rear part 30 is turned. This condition is fulfilled when the center of rotation O is at the bottom of the last 10 or it can be lower, outside the bottom plane of the last 10.

[0028] The assembly of the parts of the last 10 occurs in reverse order.

[0029] It is easy to understand that, with the design according to the invention, the removal of the last 10 can be achieved easily without exerting any tension on the upper of the shoe, whereby the object of the invention has been met.

[0030] Although the illustrated design of the portions of the last 10 is preferred, different embodiments can also provide similar results, for example the projection 35 and the opposite recess 25 are not necessarily required, or the radii of the first and second circular arcs can be the same, and the shape of the locking projection 34 can be different from the shape of the exemplary embodiment. The invention can thus not be limited to the embodiments illustrated by way of example only.

Claims

Claims:

1. A multi-part last (10) that can be disassembled in a gentle manner, comprising a front part (20), a rear part (30) and a wedge part (40) that interconnects the first two parts; wherein in assembled state the front part (20) and rear part (30) are interconnected in a form-locking manner, and the bottoms of the front and rear parts (20, 30) constitute the continuation of each other and form the bottom of the last (10), characterized in that, in that the bottom of the front part (20) has a rearwardly directed projection (21), the bottom of which forms part of the bottom of the last (10), and this projection (21) terminates in a rear support (22) having at its rear part an upwardly and forwardly directed end curved as a first circular arch (23), and above the projection (21) the front part (20) has a cavity (27) which is partially open at the top and closed at the front by a second circular arch (26), and the front lower portion of the rear part (30) has a front face resting on and fitting said first circular arch (23) of the rear support (22), and in addition the rear part (30) has a locking projection (34) introduced into and terminating in said cavity (27), the front and upper surfaces of which are curved in said second circular arc, and in the assembled condition of the last (10), a front portion of the locking projection (34) rests against the concave inner wall of the cavity (27), curved in correspondence with the second circular arc, said first and second circular arcs (23, 26) are concentric with each other and have their center points (O) at or below the line of the base, and the wedge part (40) fits into the downwardly tapering wedge-shaped opening formed between the front and rear parts (20, 30), and the assembled last (10) can be removed from the front part (20) after removal of the wedge part (40) by partial rotation of the rear part (30) about the center point (O).

2. The multi-part last according to claim 1, wherein the rear support (22) has a support surface (24) extending obliquely forwards and downwards from the upper end of the first circular arc (23), forming the rear wall of the cavity (27), the support surface (24) having a recess (25) therein, and the locking projection (34) has a projection (35) fitting into the recess (25).

3. A multi-part last according to claims 1 or 2, wherein the bottom of the wedge part (40) has a curved bottom in the arc of the second circular arc (26).

4. A multi-part last according to any one of claims 1 to 3, wherein the rear part (30) has frontal surfaces with downwardly inclined sections (31, 32), and the rear surface of the front part (20) facing in forward direction is formed by inclined lower and upper wedge sections (28, 29), and the wedge part (40) has a shape corresponding to the downwardly narrowing wedge-shaped space formed between these inclined surfaces of the rear and front parts (30, 20).

5. The multi-part last according to claim 4, wherein the upper entry section (31) of the front surface of the rear part (30) is less inclined than the lower section (32).

6. The multi-part last according to claim 4, wherein the upper section (29) of the rear surface of the first part (20) is less inclined than the lower section (28) thereof.

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