EP4166031A1

EP4166031A1 - Footwear nail having a duck beak tip

Info

Publication number: EP4166031A1
Application number: EP22201570.3A
Authority: EP
Inventors: Sergio Brizzi; Vito Conte
Original assignee: Metallurgica Lombarda Srl
Current assignee: Metallurgica Lombarda Srl
Priority date: 2021-10-14
Filing date: 2022-10-14
Publication date: 2023-04-19
Also published as: IT202100026345A1

Abstract

A description is given of a nail (1) for footwear, suitable for joining turned flaps of an upper (11) to an insole (21) of a footwear item, comprising a flat cylindrical head (5), a shank (7) and a tip (9) with section tapering from the shank (7) to a penetration tip, wherein the total length of the nail (1) is comprised between 6 and 12 mm and said tip (9) is provided with two cutting edges (91, 93) and two rounded lateral surfaces (92, 94) extending between said cutting edges (91, 93), the cross section of said tip (9) having a substantially oval shape with two sharp edges at the cutting edges (91, 93) and symmetrical with respect to the plane passing through said cutting edges (91, 93).

Description

The present invention relates to a nail for footwear and the like with an optimised configuration for the joining of the upper to the insole.

Background of the invention

Footwear in general is composed of several components, the number and complexity whereof vary according to type and uses. The main components of a shoe are the upper and the sole, which are also the externally visible components.
The upper is the higher part of shoes. It can be in leather, hide or technical materials and is formed by a single piece or several pieces sewn one to the other. Its function is to protect and wrap the foot, ensuring stability and hold.
The sole is instead the external part in contact with the ground. It can be in various materials, including rubber, wood or hide, and has the function of ensuring traction and grip.
Footwear generally also has insoles, i.e. thin linings placed inside the shoe that ensure more comfortable walking and better posture. Insoles come in different sizes and materials depending on the type of shoe and are present, in different ways, both in classic lace-up shoes and in tennis shoes, trainers and the like.
In order to make the footwear, it is necessary to carry out an operation of connecting between the insole and the turned flaps of the upper. In the case of classic shoes, this operation is normally performed by nailing, which is carried out by hammering a plurality of nails with a specially configured machine onto the edges of the insole. The nailing process takes place with the aid of a last around which the shoe is mounted, placed therefore at the face of the insole opposite the entry of the nails.
In the assembly of a shoe, this operation takes on great importance in that the nails that join insole and upper represent substantially the frame that holds the whole shoe together. The functioning of these nails - also referred to in industry parlance as 'tacks' - consists in first penetrating the material of the upper (usually leather or imitation leather or various fabrics) and subsequently the insole, to then hit a steel reinforcement plate in the last and then bending into a hook consequently holding the upper and insole hooked together. Figure 1 shows schematically the result of this process.
Three sections can be distinguished in this type of nail or tack:

a head, which must keep the upper compressed;
a shank, which must remain as straight as possible after application;
a tip, which must easily penetrate materials and must easily bend and hook when it reaches the plate of the upper.

For these purposes, the head must have a diameter such as to minimise the risk of the material of the upper being torn off, compatibly with the characteristics of the machines used. Tacks currently in use have a head with maximum diameter of 2.8 mm, normally around 2.7 mm
Known tacks generally have a "pyramid" type tip, with generally square section, with four edges or corners starting from the end of the shank. This type of tack, although widely used in the industry, is not applicable to all types of footwear, which have components of very different materials and thicknesses.
More particularly, trainers, which are shoes characterised by a rubber sole, are made of materials (including those of the insole) that are softer and more flexible with respect to traditional shoes, which do not allow the use of traditional nailing systems. For shoes such as these, different joining mechanisms are normally used, including glues and adhesives, which result in an end product with inferior functional and durability characteristics.
It should also be pointed out that the use of the tacks currently known depends strongly on the machine used for nailing and on the practicality and skill of the operators, who find it difficult to adapt the tacks to the various types of shoes, with consequent premature wear of the machinery and lasts used.

Summary of the invention

From what has been disclosed above, the disadvantages of nails for footwear currently in circulation appear clear.
The object of the present invention is therefore to provide a nail for footwear or tack that is able to overcome the disadvantages of the prior art.
More particularly, an object of the present invention is to provide a nail for footwear having a tip with flexibility such that it makes the nailing process easier, at the same time improving the characteristics of joining and hold between the materials.
Another object of the present invention is to provide a nail for footwear that can be applied to various types of footwear, including in particular trainers and the like.
These and other objects are achieved by a nail in accordance with the invention having the features listed in the appended independent claim 1.
Advantageous embodiments of the invention are disclosed by the dependent claims.
Substantially, the present invention relates to a nail (1) for footwear, suitable for joining turned flaps of an upper (11) to an insole (21) of a footwear item, comprising a flat cylindrical head (5), a shank (7) and a tip (9) with section tapering from the shank (7) as far as a penetration tip, wherein the total length of the nail (1) is comprised between 6 and 12 mm and said tip (9) is provided with two cutting edges (91, 93) and with two rounded lateral surfaces (92, 94) extending between said cutting edges (91, 93), the cross section of said tip (9) having a substantially oval shape with two sharp edges at the cutting edges (91, 93) and symmetrical with respect to the plane passing through said cutting edges (91, 93).

Brief description of the drawings

Further features of the invention will be made clearer by the following detailed description, referred to one of its embodiments purely by way of non-limiting example illustrated in the accompanying drawings, in which:

Figure 1 is a schematic view of the nailing of a tack to couple the edges of an upper to an insole by means of a last;
Figure 2 is a side elevation view of a tack according to the invention;
Figure 3 is a view of the tack shown in Figure 2 rotated axially by 90°; and
Figure 3a is a view of the section of the tip of the tack taken along line A-A in Figure 3.

Detailed description of the invention

A detailed description will now be given, with reference to the accompanying drawings, of a nail for footwear according to the invention.
Figure 1 schematically shows a nail for footwear 1 according to the invention after being driven into an insole 21 to connect it to the turned flaps of the upper 11 (with optional lining) and after being driven against a last 31. After application, the tip of the nail 1 is almost completely bent 1 so as to hook the insole 21 and keep it joined to the upper 11 thanks to the head 5. The shank 7 of the nail after application instead remains straight.
Prior to use, the nail for footwear 1 has a configuration like that shown in Figures 2 and 3 and conventionally has a circular flat head 5, a shank 7 and a tip 9.
As already pointed out during the illustration of known products, the tips for these types of nails usually have a pyramidal section that entails a series of disadvantages and limitations both during application and during common use of the shoe, due to the loads and stresses involved.
The essential characteristic of the nail 1 according to the invention is the presence of a tip 9 defined as "duckbill", i.e. with a substantially more flattened shape, shown in the section of Fig. 3A taken along line A-A of Fig. 3.
The section of tip 9 has an ovalized shape provided with two cutting edges 91 and 93 and two rounded joining surfaces 92 and 94. Figure 2 is a side elevation view of the nail showing frontally the rounded surface 92, while Fig. 3 shows the same nail 1 of Figure 2 rotated by 90°, in which the cutting edge 91 and half of the two rounded surfaces 92 and 94 can be seen.
The tip 9 thus has a duckbill configuration that starts from the shank 7 with a section like that shown in Figure 3a and ends in a penetration tip. The smaller section of the tip of nail 1 has in fact better penetration in the materials but above all has a lower modulus of flexural strength and can therefore bend more easily (along the smaller axis of the oval of the section of Fig. 3a).
This has the dual advantage of requiring a smaller thrust by the machine for nailing, with consequent less wear of the same, and of much less stress on the reinforcement plates of the lasts, prolonging durability thereof. In this way a better hold of the nailing in the shoe is also obtained.
Nails for footwear or tacks normally have a total length that varies from 5 to 12 mm To achieve the aforementioned objects, nail 1 according to the invention has advantageously a length of the tip of 4 mm, irrespective of the total length of the nail, which can vary from 6 to 12 mm. According to the intended uses, the length of the shank 7 of the nail 1 can thus vary between 2 and 8 millimetres, with a diameter comprised within the range between 1 and 1.2 mm.
A further innovative and advantageous feature of nail 1 is represented by the diameter of the head. Standard nails normally applied in the industry have a maximum diameter of 2.8 mm, normally around 2.7. Advantageously, nail 1 has a head with diameter greater than 2.8 mm, and even more advantageously of 3 mm. This configuration further optimises the hold and minimises the risk of the material of the upper being torn off.
A nail for footwear 1 thus described has functional features able to overcome the disadvantages of products currently in circulation, allowing less wear. In particular, a nail 1 provided with a tip 9 with the features described above allows use on various types of footwear, also on those in which, to date, the joining between upper and insole cannot be achieved by nailing or is extremely difficult and not very reliable. In particular, the nail or tack 1 having the features of the appended claims can be applied in an innovative manner on shoes such as trainers and the like.
The present invention is not limited to the particular embodiments previously described and illustrated in the accompanying drawings, but numerous detailed changes may be made thereto, within the reach of the person skilled in the art, without thereby departing from the scope of the same invention as defined in the appended claims.

Claims

Footwear nail (1) for joining turned flaps of an upper (11) to an insole (21) of a footwear item, comprising a flat cylindrical head (5), a shank (7) and a tip (9) of tapering section from the shank (7) to a penetration tip, characterised in that its total length is comprised between 6 and 12 mm and said tip (9) is provided with two cutting edges (91, 93) and two rounded lateral surfaces (92, 94) extending between said cutting edges (91, 93), the cross section of said tip (9) having a substantially oval shape with two sharp edges at said cutting edges (92, 94) and being symmetrical with respect to the plane passing through said cutting edges (92, 94).
Footwear nail (1) according to claim 1, characterised in that the length of the tip (9) is 4 mm.
Footwear nail (1) according to claim 1 or 2, wherein the diameter of said flat cylindrical head (5) is at least 2.8 mm, in particular around 3 mm.
Footwear nail (1) according to any one of the preceding claims, characterised in that the shank (7) has a diameter that varies between 1 and 1.2 mm
Footwear nail (1) according to any one of the preceding claims for use in the manufacture of footwear including trainers or the like.