GB2276526A - Heel top pieces - Google Patents

Abstract

A top piece for a shoe heel comprises an injection moulded ground engaging wear portion moulded around two or more pins 4, 5 which project from the wear portion. The pins fit into holes in a shoe heel to secure the top piece to the heel, without the need to use staples which are unsightly and may rip clothing. In addition the wear portion is easily removed from the shoe heel and may be replaced with a wear portion of a different hardness. A range of top pieces may be provided, each being suitable for a different application. <IMAGE>

Description

TITLE: Heel Top Pieces DESCRIPTION Field of the Invention The invention relates to top pieces for use in the manufacture of footwear, particularly ladies' footwear.

Prior Art Heeled shoes for ladies have traditionally been made either as stiletto heeled shoes or as conventionally heeled shoes. The respective methods of construction are quite different. In a stiletto heeled shoe, the loading per unit area on the heel is extremely high because of the small ground-engaging area of the top piece. It should be understood that the wear portion of the heel that actually comes into contact with the ground is referred to in the trade as the top piece, because the shoe is made upside down on a last, with the sole and heel pointing upwards.

To accommodate the high loadings, the top pieces for stiletto heeled shoes have been made from a relatively hard thermoplastics material, moulded around a securing pin which conventionally is a splined or ribbed steel pin one end of which is anchored into the injection moulded plastics material during moulding, and the other end of which is pointed and extends perpendicular from the plane of the thermoplastics material of the top piece. The heel itself is reinforced by a tubular metal strengthening member, and in use the pointed end of the securing pin is inserted into the open end of the tubular metal reinforcement, and the top piece hammered into position. It is restrained from rotation in use by the splines or ribs around the periphery of the securing pin.

Traditionally the anchorage of the embedded end of the securing pin comprises simply moulding the thermoplastics material of the top piece around a flat planar embedded head portion of the pin. This has always been sufficient to retain the top piece securely on the heel, because the hard nature of the thermoplastics material and the small heel area together make it virtually impossible for the thermoplastics material of the top piece to become prised away from the pin in use.

The traditional method of construction of larger heeled shoes has been quite different. The top piece comprises a moulded piece of thermoplastics material only, which is retained in position on the shoe heel by adhesive, by staples or by a combination of adhesive and staples. The thermoplastics material is generally relatively soft, to provide a reasonable amount of friction between the top piece and the ground when the shoe is being worn. It is of course possible to use much softer materials on large heeled shoes than on those with stiletto heels, because of the difference in area over which the load is spread.

The softer the material of the top piece, the more grip is provided between the shoe and the ground.

The staples which are used to affix the top piece to the shoe heel are simply U-shaped metal wires which are driven through the thermoplastics material of the top piece and into the material of the heel. Once the top piece is stapled in place, it is difficult to remove without the use of specialist equipment.

Recently, the use of metal staples on women's shoes has become increasingly unpopular. They are visible to the purchaser of the shoe, and detract from its appearance.

In addition, particularly with dance shoes, the staples tend to catch on tights or other clothing, sometimes causing serious damage.

Dancers often require shoes with different degrees of grip, depending on the dance being performed. In the past they have therefore required several different pairs of shoes, provided with top pieces of various hardnesses.

Because top pieces have always been attached using glue and/or staples, it has never been contemplated that it might be possible to change these top pieces between dances, rather than changing the entire shoe. If this were possible, each dancer would require only one pair of dance shoes rather than several.

Because of the significantly different wear and load requirements between the materials used to make stiletto top pieces and those used for larger top pieces, it has never been contemplated that the technology used for securing in position top pieces of one style might be transferrable, with or without a modification, to the securing in position of top pieces of the other style.

The Invention The invention provides a top piece for a shoe heel, the top piece comprising an injection moulded ground-engaging wear portion, moulded around two or more securing pins which project from the wear portion1 wherein the wear portion is made from a soft thermoplastics material having a shore hardness of 50 or less, preferably less than 47; and each securing pin is anchored to the injection moulded wear portion by having a pin anchorage portion embedded in the wear portion, and being shaped such as to make it impossible to remove the pin from the injection moulded wear portion without destruction of that injection moulded wear portion. The pins are made of a relatively hard material, which may be a metal such as steel. In a preferred embodiment, however, the pins are made of a hard plastic such as nylon.

Preferably, the anchorage portions of the pins include re-entrant portions or flow-through shapes, around or through which the injection moulded material of the wear portion can flow so as to lock the anchorage portion of the pins securely in the injection moulded wear portion.

Preferably the anchorage portions include one or more through holes through which the injection moulded material can flow during moulding. Alternatively instead of a through hole, the material of the anchorage portion may be bent or formed into a sufficiently re-entrant shape that the thermoplastics material flows around it during moulding, so as completely to lock the anchorage portion of the securing pin into the injection moulded wear portion to an extent sufficient that destruction of the wear portion would have to be necessary before the securing pin could be removed. The use of re-entrant portions formed by bending the material is particularly applicable to metal pins, which may be formed into complex shapes. Where plastic pins are used, through holes are preferable, as these can easily be incorpcrated during the moulding of the pins. Shoulders or looped shapes are difficult or impossible to achieve during the moulding process.

Preferably, the thermoplastics material of the injection moulded wear portion has a shore hardness or about 47. A preferred thermoplastics material is soft polyurethane of a hardness of approximately a 45 shore D.

Whereas in known stiletto heel technology, the securing pin is inserted into a metal reinforcing tube in the heel, the top piece of the invention can be incorporated into a shoe heel even when it has no such steel reinforcing tube, and can therefore be used on shoes with lower, broader heels. Preferably the securing pins of the top piece of the invention are simply inserted into cylindrical holes formed in the base material of the shoe heel itself. For example, that might comprise a pair of holes formed during moulding in a shoe heel made from injection moulded polystyrene or acrylonitrile-butadienestyrene resin. The invention accordingly further comprises a ladies' shoe provided with a top piece as above described, with the securing pins directly received in corresponding tubular cavities formed in the injection moulded material of the shoe heel.

Any number of securing pins may be used, depending on the size of the shoe heel to which the top piece is to be attached. Two such pins is the absolute minimum, as contrasted with one securing pin alone being the sole means for anchorage in the art of stiletto heels.

The pins are preferably slightly greater in diameter than the holes in the shoe heel into which they are intended to fit. These pins, which preferably have pointed or narrower ends to aid location, are forced into the holes in the shoe heel to form an interference fit. It has been found that whatever hard material the pins are made of, a good firm fit is established, and there is no possibility of the top piece working loose. The bcnd is further strengthened by the slight unpredictable size variations that occur in moulded plastics cn shrinkage.

These variations dictate that the positions of the pins and holes rarely correspond precisely, resulting in increased interference pressure.

Once the top pieces are in place, the pins are of course invisible, and the appearance of the heel is smart. When the heel becomes very worn, the pins may appear, and if they are made of metal, this may cause problems of slippage, marking of wooden floors, or catching on clothing. However, in a preferred embodiment, the pins are made of plastic, and do not cause any problems even if they do appear when the heel becomes worn.

Because the top pieces are simply pushed into place on the shoe heel, they may be prized off easily using a screwdriver or similar tool. Any top piece may therefore be replaced by another of different hardness. A range of top pieces may be made available, each suitable for a different application. Preferably, the different top pieces should be fitted with different coloured pins to enable the user to distinguish quickly between them. For instance a top piece of shore hardness 45 may be fitted with red pins, one of shore hardness 47 with black pins and of shore hardness 49 with green pins. Accordingly, the invention includes a shoe provided with a set of heel top piees equipped with different coloured pins.

Drawinas Figure 1 is a plan view of a top piece according to the invention; Figure 2 is a vertical section through a top piece according to the invention fitted with steel anchorage pins; Figure 3 is a perspective view of a steel anchorage pin as used in Figure 2; Figure 4 is, for comparison purposes only, a side elevation of a steel anchorage pin of a conventional top piece for a stiletto heel; and Figure 5 is a perspective view similar to that of Figure 3, but through an alternative steel anchorage pin having a head style with through holes.

Figure 6 is a vertical section through a top piece according to the invention fitted with nylon anchorage pins; Figure 7 is a perspective view of a nylon anchorage pin as used in Figure 6; Figure 8 is a side view of a pin similar to that of Figure 7, but being provided with different anchorage means; Figure 9 is a perspective view of a pin similar to that of Figure 7, but being suitable for use with a shoe of small heel area; and Figure 10 is an illustration of the way in which a top piece according to the invention may be fitted in a shoe heel.

Referring first to Figure 1, the top piece comprises an injection moulded ground-engaging wear portion 1, which has been injection moulded around two identical upstanding anchorage pins 2. This top piece is suitable for a relatively small heeled shoe and therefore contains only two pins.

Figure 2 shows a top piece fitted with steel pins, shown in perspective in Figure 3, each pin comprising a bottom head portion in which an initially hollow cylindrical portion has been equally divided into fcur blade portions 3, each of which has been bent outwardly and upwardly to form a re-entrant zone in to which thermoplastics material can flow during injection moulding to provide a complete ancorage of the pin in the thermoplastics material of the wear portion 1.

Figure 5 illustrates an alternative form of the pin head, which incorporates through holes 5 in place of the upturned and outturned portions of Figures 2 and 3, and which surprisingly results in a pin which is just as resistant to removal from the thermoplastics material as is that of Figures 2 and 3.

Figure 6 shows a vertical section through a top piece fitted with nylon securing pins, and Figures 7 to 9 show a selection of possible different shapes of nylon pin.

The pins shown in Figure 6 comprise a bottom head portion (4) including two through holes (5), into which thermoplastic material can flow during injection moulding to provide anchorage of the pins in the heel top portion.

Such through holes are easy to include when moulding the nylon pins. The pin of Figure 7 includes similar flow through portions, whereas that of Figure 8 includes an upturned ledge (6) around which the thermoplastic material may flow to lock the pin into place. The pin shown in Figure 9 is suitable for use with small heeled shoes, where there is not sufficient room for a widened head portion. In this case, the base of the pin is provided with a hole (10) through which the thermoplastic flows during moulding. Each nylon pin has a narrowed area (11) at its tip, to ease location and insertion into a shoe heel. The body of the pin may be bevelled, as in Figures 6, 7 and 8, or plain, as in Figure 9.

Figure 4 shows the conventional shape of the steel securing pin of a stiletto heal, which comprises a simple head which in use is retained in the hard injection moulded thermoplastics material of the wear portion of the top piece. It will be appreciated that when the thermoplastics material is a soft material having a shore hardness of 50 or less, a simple head shape such as that shown in Figure 4 is inadequate to prevent the thermoplastics material from peeling away from the head of the pin. It is, however, surprising that the anchorage of the pins in the top piece of the invention is so strong as to retain in position top pieces of a significant surface area, which of course are much more likely to bend than would be the small and hard ground engaging portion of a stiletto top piece. This anchorage is effective for even very soft thermoplastics materials, even those having a shore hardness of less than 40.

Figure 10 shows schematically how a top piece according to the invention is inserted into a shoe heel. The shoe heel is provided with holes complementary to the pins of the top piece, but of slightly smaller diameter. The pins are forced into these holes to form a strong interference fit. When it is desirable to use a top piece of different shore hardness, to obtain altered frictional characteristics, the top piece is simply prized off using a screwdriver or similar instrument, and replaced with a different top piece. The shore hardnesses of the various top pieces are selected with reference to the colours of the pins.

Claims (9)

CLAIMS:

1. A top piece for a shoe heel, the top piece comprising an injection moulded ground-engaging wear portion, moulded around two or more securing pins which project from the wear portion, wherein the wear portion is made from a soft thermoplastics material having a shore hardness of 50 or less; and each securing pin is anchored to the injection moulded wear portion by having a pin anchorage portion embedded in the wear portion, and being shaped such as to make it impossible to remove the pin from the injection moulded wear portion without destruction of the injection moulded wear portion.

2. A top piece according to claim 1 wherein the securing pins are made of a hard plastic material.

3. A top piece according to claim 1 wherein the securing pins are made of metal.

4. A top piece according to any preceding claim wherein the anchorage portions of the pins include portions or shapes around or through which the injection moulded material of the wear portion can flow so as to lock the anchorage portion of the pins securely in the injection moulded wear portion.

5. A top piece according to any preceding claim wherein the wear portion is made of a soft thermoplastics material having a shore hardness of less than 47.

6. A shoe provided with a top piece according to any preceding claim, wherein the heel of the shoe includes tubular cavities into which the securing pins are fitted.

7. A shoe provided with a set of different heel top pieces each according to any of claims 1 to 5, the top pieces being equipped with different coloured pins.

8. A top piece substantially as described herein with reference to the drawings.

9. A shoe provided with a top piece substantially as described herein with reference to the drawings.