US 2931110 A
Description (OCR text may contain errors)
April 1960 R. PIETROCOLA 2,931,110
sou: AND HEEL UNIT FOR SHOES AND THE LIKE Filed Feb. 26, -1957 2 Sheets-Sheet 1 April 5, 1960 R. PIETROCOLA SOLE AND HEEL unrr Fox saoss AND ms LIKE 2 Sheets-Sheet 2 Filed Feb. 26, 1957 United dtates SOLE AND EEEL UNIT FOR SHOES AND THE LIKE Roberto Pietrocola, Milan, Italy Application February 26, 1957 Serial No. 642,516
1 Claim. (Cl. 36-30) This invention relates to frames for shoes and the like and, more particularly, to units comprising soles and heels.
It is an object of the invention to provide an improved unit having a heel and sole formed of one piece of material so as to facilitate manufacture.
The difficulty inherent in such an arrangement is that, since one piece of material is involved, it is hard to combine the different properties essential to both the heel and the sole. Never-the-less, the invention does provide a very practical unit and in so doing combines, for example, the normally incompatible requirements of rigidity for the heel with flexibility for the sole and strength of the frame with comfort for the foot and so forth.
In achieving the above and other of its objectives, the invention proposes heel, shank and sole portions which are all of a single piece of relatively rigid material so that the heel may have substantial structural strength. To provide the sole, which is also of said rigid material, with the necessary flexibility, the invention proposes a system of openings at least one of which constitutes a recess at the top of the sole. Finally, to provide comfort for the foot, a resilient material is accommodated in the openings to support said foot. As a feature of the invention, this resilient material is also used for ground or floor contact.
The structure of the invention is ideally suited for ladies shoes wherein the high heels must have suitable strength while, at the same time, the sole must be flexible.
Other objects and features of the invention will be found in the following detailed description as illustrated in the accompanying drawing in which:
Fig. 1 represents a mould wherein, by an injection process, there is moulded a frame provided in accordance with the invention.
Fig. 2 represents a second mould for the injection moulding of the above-noted resilient material.
Fig. 3 represents, on an enlarged scale, a cross-section of the frame obtained from the second mould.
Figs. 4, 5 and 6 represent three different forms of sole which can be obtained with the illustrated moulds.
Figs. 7 and 8 represent different forms of heels suitable for the frame of the invention.
The mould shown in Fig. 1, for producing the portion of the frame made of the relatively rigid material, is made in two parts 1, 2. For sake of simplicity, the mould is shown as having a single cavity, but it could have several cavities, so as to allow the moulding of several frames at a time. The mould is provided in the usual way with a gate 3 for injecting the plastic material. This mould serves for the whole frame, inclusive of the heel, and is used with a tough and substantially non-resilient plastic material, such as polyamide, a high molecular wei ht or low pressure polyethylene, or a polypropylene. In correspondence with the upper sole portion, the mould has a protruding portion 4, having a plurality of bosses 5, which will produce in the moulded frame corresponding through 2,931,110 figs Patented ARJY- 5, 1969 holes. Similar bosses 5 are also provided in the lower portion of the mould and serve to obtain an enlarged recess in each through hole. When the two parts of the mould are closed together the plastic material is injected through the gate 3 and the plastic is set in the usual way. The mould provides the moulded frame with the shape shown in dotted lines in Fig. 1 and in solid lines in Fig. 2. The central portion to Fig. 2. As it can be seen in this figure, the frame has a thinned out portion 7, in correspondence of the protruding portion 4, and through holes 8 with enlarged bottom recesses 9 corresponding to bosses 5. The frame or body thus obtained is then placed in the second mould, as represented in Fig. 2, which is made in two parts 11, 12 and provide with the injection gate 13. The lower portion of the mould has cavities 14 which are provided in correspondence with the enlarged portions of the through holes 8. The frame is placed between the two parts of the mould and a plastic material is injected. This plastic material is very resilient and soft and is, for instance, a highly plastified polyvinyl. The two parts of the mould, upon closing, clamp a portion of the sole and precisely that portionhaving the holes 8 with the recesses 9. When the mould is closed so as to exercise a sufficient pressure on the sole, there is injected the plastic material which fills the cavities 9 and the holes 8. The plastic material injected in this second operation takes the shape as represented in Fig. 3. It cannot be separated from the frame or body and bulges out forming the projections 14' on which one walks.
Of course by modifying the moulds and especially the lower portions 11 it is possible to obtain several types of soles, depending from the shape of the cavities 14. Thus, in the mould as represented in Figs. 2. and 3, such recesses are separated from one another, so that in the holes there are obtained single separate circular projections 15, as indicated in Fig. 4. If said recesses 14 are connected to each other by means of grooves, it is possible to obtain soles as represented in Fig. 5 or 6, according to which said channels may be straight or Zig-zag. Of course many other shapes are obtainable so as to vary the protruding portions of the elastic material.
Instead of injecting the plastic material in the second mould, it will also be possible to use natural or synthetic rubber, in which case the rubber has to be vulcanized in a similar mould, provided with heating means. It is thus possible to obtain with the same process soles partially constituted of rubber, by subjecting to vulcanization the whole frame inserted in the second mould. In this case, the sole as represented in Fig. 2 is placed in the part 11 of the mould, and in the same there is placed a suflicient amount of a natural or synthetic rubber compound. Then the mould is closed by applying downward pressure on the upper part 12, and the mould is heated to the temperature required for vulcanizing the rubber. The mould is then closed under pressure for the necessary time for the complete vulcanization of the rubber and then it is opened to extract the finished piece.
In the mould as represented in Fig. 1, the heel is obtained in a single piece with the frame and is shown only schematically. The heel can actually be obtained in 7 the moulding such as by inserting the wooden core in the mould before injecting the plastic material.
Furthermore, the heel may have a cylindrical cavity 22 which serves to receive a small wooden plug 23 onto which is nailed or screwed a replaceable wearing piece 24. This small auxiliary wearing part can thus be easily changed when worn.
The frames or bodies obtained by the described methods offer the following advantages:
(1) Possibility of obtaining rigid heels and flexible soles both of the same piece of material.
(2) Good ground adherence with no danger of slipping,
(3) Silent tread.
(4) Maximum wearing resistance of the sole.
In general, the constructive details of the moulds, and of the frames may vary according to needs without departing from the field of the present invention. 7
What I claim is:
An. integral sole and heel unit comprising a sole portion, a high heel portion, a shank-portion between the sole and heel portions, all of the portions being of a single piece and of a substantially rigid material so that the heel portion is of substantial structural strength, said sole portion having upper and'lower surfaces and having a recess in the upper surface and a plurality of openings in the lower surface communicating with the recess to render the sole flexible, and a resilient material in said recess and openings to provide comfort for the foot of a wearer as well as means for contacting the ground.
References Cited in the file of this patent UNITED STATES PATENTS Kinsley Oct. 8, 1861 Ellithorpe Sept. 10, 1918 Jones July 11, 1922 Sims June 2, 1925 Perugia Dec. 7, 1926 Hartung June 21, 1927 Bateman July 10, 1928 McQueen Mar. 4, 1930 Westheimer July 25, 1939 Wehr June 6, 1944 Van Der Veen Dec. 21, 1948 Dadisman May 30, 1950 Dratler Mar. 13, 1951 Danielson et al. Aug. 26, 1952 Danielson et a1 Sept. 9, 1952 McCord June 2, 1953 Holt May 15, 1956 Helle Dec. 11, 1956 FOREIGN PATENTS France Nov. 26, 1925 France Apr. 22, 1940 France Nov. 6, 1944 France July 15, 1953