Technical Field
[0001] In the manufacture of high heels for ladies' shoes, the main body of a heel is usually
made of a light, rigid plastics material such as polystyrene. It is then necessary
to provide a top piece of a more durable material to protect from wear the surface
of the heel that is in contact with the ground. Such a top piece may be fastened to
the heel by means of a heel pin having a head embedded in the material of the top
piece and a shaft wedged tightly in a reinforced hole in the body of the heel.
[0002] Fashion often dictates that high heels should be as slender as possible and consequently
the small area of the top piece is subjected to high pressure and increased wear,
requiring a highly resilient material if the top piece is to have a satisfactorily
long useful life. Another problem to be overcome in the design of a top piece is the
tendency of the top piece to be levered away from the heel pin if the heel becomes
somehow trapped during use.
Background Art
[0003] Metal top pieces which overcome the above problems are known but their rigidity allows
for no absorption of the impact of the footfall and so the foot is uncomfortably jarred
on each step. Therefore it has been found preferable to use plastics materials for
top pieces. However, the steel heel pin generally used for securing a plastic top
piece to a heel has a jagged head to improve its bond with the plastic. When wear
causes the pin head to be exposed to the walking surface of the top piece, its sharp
edges can cause great damage to floor surfaces and particularly to those made of wood.
[0004] One known method of making a plastic top piece which avoids some of the aforementioned
problems is to surround the head of the heel pin with a highly resilient plastic cap
and to construct the rest of the top piece from a more flexible material which cushions
the footfall, is less prone to skidding on smooth surfaces and causes less damage
to floors.
[0005] Wear is accentuated on that portion of a plastic top piece that lies below the pin
head in use because there is a reduced thickness of plastic in that portion to absorb
the impact of each footfall. Thus a small pin head is desirable for prolonging the
life of a top piece because of its small area of accentuated wear and the extra thickness
of plastic it accommodates.
[0006] Patent Specification GB 1024185 discloses a heel dowel for attaching a lift to the
heel of a woman's shoe, wherein the shank of the dowel extends substantially the full
height of the heel. The dowel has an enlarged head in the form of a slotted, cylindrical
cup through and around which the lift material is moulded to form a mechanical interlock.
[0007] Patent Specification GB 936597 discloses a heel lift with a similarly elongated metallic
pin member having a head embedded in the lift body and openings in the side walls
of the head through which an elastic material forms a mechanical bond.
[0008] In each of these documents the described construction of the head portion requires
that it be of a greater diameter than the shank. Thus the head must inevitably be
large, especially since in the described embodiments the shank is long enough and
thick enough to provide the heel's strength. This prevents the manufacture of heels
as slender as might be desired and gives poor resistance to wear.
The Invention
[0009] The invention provides a heel pin for securing a top piece on a ladies' shoe heel,
which pin comprises a knurled shank for driving into a reinforcement tube moulded
in the heel, a collar around an end of the shank, a head above the collar, a cup formed
in the top of the head, and an aperture through a side of the head to the cup.
[0010] The invention further provides for such a heel pin further comprising a cap of plastics
material moulded around the head and within the cup and connecting through the aperture
to form a mechanical interlock between the cap and the head of the pin.
[0011] This construction allows for the head of the pin to be relatively small compared
with the diameter of the shank and so top pieces may be attached to more slender heels
than was previously possible, without reduction in the strength with which they are
attached. Also, the extra thickness of plastic accommodated by a small pin head provides
longer and more even wear.
The Drawings
[0012]
Figure 1 is an elevation of a heel pin according to the invention;
Figure 2 is a section on line 2-2 of Figure 1;
Figure 3 is a section on line 3-3 of Figure 1;
Figure 4 is a plan view of a heel pin including a plastic cap, showing its location
in a top piece; and
Figure 5 is a section on line 5-5 of Figure 4.
Best mode for carrying out the invention
[0013] Figure 1 shows a heel pin comprising a shank 10 and a head 12 separated by a collar
14 around the circumference of the shank. In the illustrated embodiment, the shaft
10 has a conical point 16 at the end remote from the head 12, for ease of insertion
into a reinforcement tube in a shoe heel. The shank 10 is also provided with a knurled
portion 18 in the form of ridges extending longitudinally along the shaft from the
collar 14. When, in use, the heel pin is located in the reinforcement tube, the ridges
engage the inner surface of the tube to prevent relative rotation of the heel pin
and the heel.
[0014] The sections of Figures 2,3 and 5 help to illustrate the structure of the head 12
of the pin. The head 12 is formed on the collar 14 such that the outer diameter of
the head is smaller than the diameter of the collar. Within the head 12 a cup 26 is
formed so as to be surrounded by a cylindrical wall 20. At least one aperture is cut
through the wall 20 to the cup 26 and in the preferred embodiment the aperture is
in the form of a single transverse slot 22, extending approximately halfway around
the circumference of the wall 20 as shown in Figure 3.
[0015] Figures 4 and 5 illustrate a cap 24 made of a plastics material surrounding the head
12 of the pin. The cap 24 is moulded around the head 12 when the plastic is in a liquid
state, enabling the liquid plastic to fill the cup 26, to surround the outer surface
of the wall 20 and to flow through the slot 22, thereby connecting together the plastic
within the cup 26 and the plastic outside the wall 20. This ensures that, when the
plastic is set, there is a mechanical interlock between the cap 24 and the head 12
so that the cap can only be detached by breaking the plastic.
[0016] For use in particularly slender heels, the cap 24 may constitute the whole of the
top piece but more usually the cap wil be located in a hole in a separate top piece
28 of more flexible material, as illustrated. The shank 10 of the heel pin is driven
into a reinforcement tube in a shoe heel and the cap 24 is shaped so as to hold the
top piece 28 firmly to the heel, with the walking surface 30 of the cap 24 lying flush
with the walking surface 32 of the top piece 28. The cap 24 may be provided with protrusions
34 to hinder relative rotation between the cap and the top piece 28 during use. Alternatively,
the material of the top piece 28 may be chosen to have a slightly higher melting point
than that of the cap 24. Then, if the top piece 28 is moulded around the cap 24, there
will be some melting of the material of the cap where it contacts the material of
the top piece, forming a strong bond between the two.
1. A heel pin for securing a top piece on a ladies' shoe heel, which pin includes
a knurled shank (10) for driving into a reinforcement tube moulded in the heel, and
is characterized in having: a collar (14) around an end of the shank (10), a head
(12) above the collar (14), a cup (26) formed in the top of the head, and an aperture
through a side of the head to the cup.
2. A heel pin according to claim 1 wherein the aperture through the side of the head
(12) to the cup (26) is a transverse slot.
3. A heel pin according to claim 1 or claim 2 further including a cap (24) of plastics
material moulded around the head (12) and within the cup (26) and connecting through
the aperture to form a mechanical interlock between the cap (24) and the head (12)
of the pin.