WO2001001015A1

WO2001001015A1 - Wire rope socket

Info

Publication number: WO2001001015A1
Application number: PCT/US1999/019774
Authority: WO
Inventors: Charles E. Lucas
Original assignee: The Crosby Group, Inc.
Priority date: 1999-06-25
Filing date: 1999-08-27
Publication date: 2001-01-04
Also published as: AU6241099A

Abstract

A socket (10) for an end of a wire rope. The socket includes a basket (14) with a conical inner surface (16) and a conical outer surface (18), said inner basket surface having an opening (22) for receiving the wire rope. A resin or zinc nose-cone secures an end of the wire rope in the socket. The use of a resin nose-cone in the socket ensures that the socket only bears the force of a load on the wire rope near a neck (24). As a result, a thickness of an annular wall near the neck is tapered away from the neck.

Description

WIRE ROPE SOCKET

BACKGROUND OF THE INVENTION

1. Field of the Invention.

The invention relates to spelter sockets for wire ropes.

2. Description of the Related Art.

Wire rope sockets are commonly used as mechanisms to attach and connect wire

ropes to hooks, shackles, or similar devices. It is common for loads for large diameter wire rope to be several tons. For example, one common application for large wire ropes is the

mooring of ships or vessels. To support these very heavy loads, the sockets often require

substantial volumes of expensive steel material and the sockets may weigh as much as 500

pounds.

In the existing art, sockets have been filled with molten zinc or zinc alloy to secure

a wire rope to a "spelter socket." The socket is filled while the zinc is in the molten, liquid

state and allowed to cool to form a solid. For example, Kelly (U.S. Patent No. 4,642,854)

discloses a wire rope anchored by molten zinc in a spelter socket. The socket has annular

grooves 3 disposed in an internal surface of the socket, to help secure the zinc in the socket.

Other examples of spelter sockets include Timmington (U.S. Patent No. 5,024,548)

and Michaelsen (U.S. Patent No. 3,568,265).

It is also known in the art to use resin as an anchoring substance in place of zinc in

a wire rope socket. For example, a resin with the trade name Wirelock® is a common resin

used in a wire rope socket.

Wire rope sockets have been designed in the past to have a frusto conical "basket"

portion with a wall which was thinnest near a neck, and which increased in thickness away

from the neck. However, this is not the most efficient design for a wire rope socket. SUMMARY OF THE INVENTION

The present invention is for a wire rope socket with an annular conical wall that tapers

in thickness away from a socket neck. A nose-cone of resin secures the wire rope in the

socket and provides a medium to transmit a force on the wire rope to the socket. The socket

is made of steel. An annular conical wall with an inner surface and an outer surface defines

a first end of the socket. A bail, or loop, defines a second end of the socket.

One object and purpose of the present invention is to provide a wire rope socket

which is less expensive to make.

Another object and purpose of the present invention is to provide a wire rope socket

where the volume of socket material and the socket's internal wall stresses are minimized.

A further object and purpose of the present invention is to provide a wire rope socket

where the thickness of the conical wall varies without sacrificing strength.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a wire rope socket constructed in accordance with

the present invention;

Figure 2 is a front elevation view of a wire rope socket of the present invention shown

in Figure 1 ;

Figure 3 is a side elevation view of a wire rope socket of the present invention shown

in Figure 1 ;

Figure 4 is a top view of a wire rope socket of the present invention shown in Figure

i; Figure 5 is a bottom view of a wire rope socket of the present invention shown in

Figure 1;

Figure 6 is a schematic, exaggerated view of the position of the resin nose-cone after

the resin has cooled;

Figure 7 is a schematic view of the resin nose-cone in a wire rope socket; and

Figure 8 is a schematic view of the resin nose-cone and wire rope socket, showing the

pressure distribution transmitted from the wire rope to an inner frustrum surface of the wire

rope socket.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Like part numbers in the various embodiments correspond to like parts of the

invention.

Referring to the various views of a single embodiment of the invention shown in

Figures 1 through 5, a wire rope socket 10 has a bail 12 and a basket 14. The bail 12 will be

engaged with a fitting or a rope (not shown). The basket 14 has a frusto conical inner socket

surface 16 and a frusto conical outer socket surface 18, with an annular wall 20 defined

between the two socket surfaces 16 and 18.

The inner socket surface 16 defines an opening 22 through which an end of a wire

rope may fit and be inserted. The annular wall 20 has a rounded neck 24 near the opening

22. The thickness of the annular wall 20 is tapered, becoming progressively smaller away

from the rounded neck 24. Accordingly, as the thickness of the annular wall 20 decreases,

the outer socket surface 18 increases in diameter.

The inner socket surface 16 is conical with an axis 26 and a cone angle 28, illustrated

by the intersection of the dashed lines. The outer socket surface 18 is conical, with the axis

26 common to the inner socket surface 16. The outer socket has a cone angle 30 illustrated

by the intersection of the dashed lines. A diameter measured from the axis 26 to the inner

socket surface 16 is defined as D, and a diameter measured from the axis 26 to the outer socket surface 18 is defined as D₂. An annular area (Ann) of the annular wall 20, in a plane

normal to axis 26, is then defined as:

A_Ann = (π / 4) x [(D₂)² - (D,)²].

In one embodiment, the annular area 36 is substantially equal, or varies by less than

20 %, from the neck 24 to a basket top 38. Stated in other words, the cross-sectional area of

the basket remains fairly constant. A loop 34 of the bail 12 is located above the basket 14 and connected thereto. The

bail 12 and the basket 14 are integral parts of the wire rope socket 10. The bail 12 has two

symmetric walls 36 and 38, which are opposed to each other near the basket 14. As the walls

36 and 38 extend away from the basket 14, the walls 36 and 38 curve inwardly forming loop

34, and join to form an eye 40. A shackle or hook or other fitting (not shown) may fit

through the eye 40 and engage the bail 12, for connecting the wire rope socket 10 to a chain,

a winch or a similar device.

The reduced area of the basket allows for reduction of the outer diameter of the outer

socket surface 18 over the prior art. This also reduces the bending stress when the spelter

socket and accompanying fitting are pulled over sheaves or the like.

Figure 6 is a schematic representation showing a conical resin nose-cone 42 formed

about a wire rope 44 positioned in the basket 14. To form the resin nose-cone 42, the inside

of the basket may be roughened to enhance the interface of the resin and the socket. A wire

rope end 46 is first placed inside the basket 10, with the wire rope end 46 extending past a

basket end 48. The strands of the wire rope are unlayed. A fiber core in the wire rope is cut

out. The individual wires of each strand are unlayed. Additionally, any plastic material is

removed from the broomed area. The end of the wire rope will be degreased and cleaned

using known procedures. The socket will then be placed over the resulting broom until the

wires are level with the top of the socket basket or to a minimum embedded length. The base

of the socket may be sealed with putty or other material to prevent leakage of the resin. The

resin is poured into the socket until the socket basket is filled. The socket will remain in a

still position for a sufficient length of time for the resin to gel and cure.

In one embodiment, the resin may consist of polyester resin, polystyrene or other

types of polymers. As the resin cures to a solid form, it flashes off during an exothermic chemical reaction and gives off heat during the curing process. The wire rope socket 10 is

positioned vertically as shown in Figure 1, so that the resin nose-cone 42 is formed

concentric to the wire rope 44. Next, resin is poured into the basket 14 in the liquid state and

allowed to cool and/or cure. Upon cooling and/or curing, the resin shrinks volumetrically by

about 2% and the resin nose-cone 42 pulls away from the inner basket surface 16, as shown

in Figure 6.

When a load L is applied to the wire rope 44 axially in the direction shown by arrow

52, any portion of the resin nose-cone 42 adhering to the inner basket surface 16 shears and

the resin nose-cone 42 only engages the inner basket surface 16 near the neck 24. The resin

plastically deforms and causes some of the resin nose-cone 42 away from the neck 24 to

engage the inner basket surface 16. This in turn causes more of the inner basket surface 16,

away from the neck 20, to bear more of the load L.

Figure 7 and 8 are schematic representations of the forces and pressures exerted by

the resin nose-cone 42 on the inner basket surface 16. As load L increases, the resin nose-

cone 42 seats progressively, generating forces N normal to the inner basket surface 16. These

normal forces N are transmitted through the resin nose-cone 42 to the surface of wire rope

44. The resin nose-cone 42 effectively creates a wire-reinforced composite wedge on the

wire rope end 46.

Because of the changes in the external force distributions acting on the wire rope

socket 10 caused by the action of the resin nose-cone 42, the annular wall 20 is thickest near

the neck 24, and tapers to a narrower thickness away from the neck 20. Because of this

tapering, a smaller annular wall thickness is required in areas where the basket is widest.

This can be viewed in two advantageous ways. First, for equivalent loads, less material is needed to form the annular wall because

the socket does not need to be as thick in the wider annular volumes forming the socket.

Second, for an equivalent amount of steel used to form the wire rope socket, the steel may

be concentrated nearer the neck region, where the loads transmitted from the wire rope

through the resin is higher.

Typical values of the inner surface cone angle 28 and the outer surface cone angle

30 are between 9 and sixteen degrees. For the wire rope sockets 10 described above, the

annular wall 20 is designed to carry between 70 % and 80 % of the load L for a distance one-

third of the cone height 50 away from the neck 20. This relationship is shown schematically

in Figure 8.

As described above, the wire rope socket is particularly suitable for use with resin

nose-cones. However, the same type of basket wall design is also effective using zinc or zinc

alloy in place of resin.

The design of the basket with a smaller annular wall thickness near the bail also helps

to prevent bending or kinking of the wire rope when one uses the socket with pocket sheaves

or tailboard rollers.

Claims

What Is Claimed Is:

1. A socket for an end of a wire rope, comprising:

(a) a basket with a conical inner surface and a conical outer surface, said

basket inner surface having an opening for receiving said wire rope; (b) an annular wall between said basket inner surface and said basket outer

surface;

(c) a neck of said annular wall extending near said inner basket surface

opening, wherein a thickness of said annular wall is greatest at said neck and becomes

progressively smaller away from said neck;

(d) a bail integrally connected to said basket,

(e) said bail having symmetric walls which are:

(i) opposed near said basket; and

(ii) curved inwardly to integrally j oin away from said basket; and

(f) a nose-cone disposed between the wire rope and said annular wall, to

secure the wire rope to the annular conical wall and to distribute forces caused by external

loads on said wire rope over said annular conical wall.

2. The socket for a wire rope of Claim 1 wherein said nose-cone is formed from

an initially liquid resin which cures to a solid.

3. A socket for a wire rope of Claim 1 wherein said bail has symmetrical walls

which are opposed near said basket and curved inwardly to integrally join away from said

basket.

4. The socket for a wire rope of Claim 1 wherein said nose-cone is formed from

initially liquid zinc which cools to a solid.

5. The socket for a wire rope of Claim 1 wherein annular areas of said annular

wall, in planes normal to an inner basket surface cone axis, do not vary by more than 20%

from said neck to a basket top.

6. A socket for an end of a wire rope, comprising:

(a) a basket with a conical inner surface having diameter D , and a conical

outer surface having diameter D₂, said basket inner surface having an opening for receiving

said wire rope; and

(b) an annular wall between said basket inner surface and said basket outer

surface, wherein said annular wall has an annular area, Ann defined as

A_Ann = (π / 4) x [(D₂)² - (D,)²]

and wherein said annular area varies by less than 20% throughout.