EP0250634A1

EP0250634A1 - Nonskid hobnailed undershoe

Info

Publication number: EP0250634A1
Application number: EP86109079A
Authority: EP
Inventors: Giovanni Salutati
Original assignee: PROTECTOR SAL Sas di Giovanni Salutati
Current assignee: PROTECTOR SAL Sas di Giovanni Salutati
Priority date: 1986-07-03
Filing date: 1986-07-03
Publication date: 1988-01-07

Abstract

A nonskid hobnailed undershoe composed of a sheath (4) of elastic material with a shaped insert of semiflexible, resilient material as sole, said insert having downward protruding metal nails (1), is specified herein.

Description

This invention concerns a nonskid hobnailed undershoe which can be worn under usually worn shoes directly and quickly. Precisely, the hobnailed.undershoe concerned allows to avoid skidding when one walks on icy and/or snowy surfaces with no need of wearing special shoes or boots. An essential feature of this invention is that the undershoe is a sheath of elastic material, which has an open upper side into which the usual shoe wearing foot can be inserted and a lower side that comprises a sole of resilient, semiflexible material that, on its turn, comprises a range of nail-shaped metal inserts, the points of which protrude out of the sole of resilient material and are turned toward the outside of the sole. A further main feature of the invention is that the sole of resilient material is shaped with grooves alternated with protrusions. In a favourite type of the invention, the grooves and the protrusions are parallel, have a rectangular section parallelepiped shape and are arranged transversally to the main dimension (length) of the undershoe.
The metal nails, which are preferably made of stainless steel or other hard, stainless metal alloys, are favourably inserted into the protrusions. It is obvious to any expert in this line that many other shapes and arrangements of protrusions and grooves in the stiff side of the sole of the undershoe concerned are possible, such as a range of rolls or square-based parallelepipeds, evenly arranged on the sole surface. In any case, the ratio between the contact surfaces of the protruding parts to the ground and the total surface of the undershoe sole shall range from 40 % and 70 %. Lower values of protruding surface are unfavourable and make walking uncomfortable, while higher values reduce the grip of protrusions on snow. The quantity of metal nails inserted into the protruding parts of sole, is typically 20 to 60 nails in total per .sole. The points of said nails protrude from the semirigid side of sole for an height O.1 to 2 mm; in the favourite model the value of said protrusion is 0.2 to 0.6 mm. Among the elastic materials that are very useful to make the undershoe under this invention we can mention natural and/or synthetic polymeric materials of elastomeric type such as natural rubber, SBR, nitrile,.chloroprene, butyl, ethylene-propylene, silicone, fluoride, polyurethan elastomers, both as vulcanizable moldable masses and as latexes.
Obviously, it is also possible to compound the above said elastomers with normal additives used in rubber industry in order to obtain particular performances or looks or reductions in:,the-costs of finished goods. Among the semirigid, resilient materials suitable for making the sole of the undershoe concerned, polymer materials of thermoplastic type, such as polyesters, polyamides, polycarbonates, polyacetales, polyolefines, polyacrylics, polyurethanes, ABS, PVC proved particularly suitable. In this case, too, like the elastomeric materials for sheath, the above said materials can be compounded with their proper additives, plasticizers, pigments commonly used in the rubber industry and compatible with the chosen material, in order to get the rigidity-, resiliency- and abrasion resistance - values required for the specific case. Molding of this undershoe according to this invention can be done with the usual molding or casting methods used for the single materials. Molding or casting are performed as a two-stage process: during the first stage the sole with metal inserts is molded, during the second stage the sheath is molded and the sole is used as an insert. This following-insert two-stage process makes the finished piece particularly resistant, because there is no possibility of unsticking of the sole from the sheath.
The attached figures show a favourite type of the invention.
In particular

FIGURE 1 is a plan view of the lower side of the undershoe
FIGURE 2 is a side view of the undershoe on Fig.1 and
FIGURE 3 is a plan view of the upper side of the undershoe concerned.

Making reference to the above figures, the hobnailed undershoe of th shown type is a sheath of vulcanized natural rubber into which, before vulcanizing, an insert or molded ABS polymer having a range of rectangular section parallelepiped protrusions 2 with inserted steel nails 1 was inserted.
The parallelepiped protrusions 2 are spaced by grooves 3 so that the lower surface of the protruding part amounts to 60 % of the total sole surface.
Height and shape of the side edge of the sheath 4 . guarantee the best bodying between the lower edge of the footwear inserted into the undershoe concerned and the undershoe under this invention.
Typically, the side edge of the sheath is 1 to 3 cm. high, while the front side is shaped to enclose shoe- tip for a length of 2 to 4 cm. and the back side is 3 to 6 cm. high. It is clear that the undershoe under this invention can be made in different shapes suitable to be easily worn both on standard shoes and on climbing-or ski-boots, both for men and for women.

Claims

1. Nonskid hobnailed undershoe directly and quickly wearable under usual footwear, featured by a sheath of elastic material the upper side of which is open and the lower side of which has an inserted sole of resilient, semiflexible material that, on its turn, encloses a range of nail-shaped metal inserts, the points of which protrude out of the sole of resilient material and are turned toward the outside of the sole.

2. Hobnailed undershoe according to the claim 1, featured by a sheath of elastic material having a 1 to 3 cm. high side edge, a front side shaped to enclose shoe- tip for a length of 2 to 4 cm. and a 3 to 6 cm. high back side.

3. Hobnailed undershoe according to the claims 1 and 2, featured by the fact that its sole of resilient, semiflexible material is shaped with a range of protrusions alternated with grooves, so that the ratio of the contact surfaces of the protruding parts in touch with ground to the total surface of the undershoe sole is 40 % to 70 %.

4. Hobnailed undershoe according to the claim 3, featured by the fact that the grooves and the protrusions have rectangular section parallelepiped shapes, are parallel and arranged transversally to the main dimension of the undershoe.

5. Hobnailed undershoe according to claim 3 featured by the fact that the metal inserts in the sole protrusions of resilient material protrude from the soles for an height of 0.1 to 2 mm and there are 20 to 60 inserts per sole.