BACKGROUND

The present invention relates to a split nut assembly. More specifically, the present invention relates to a split nut that defines at least two axially extending bores through which the split extends.

A common problem with nuts is that, when they have been subject to axial forces, they become jammed on the threaded shaft to which they are threadably secured. To dissipate the internal forces and facilitate relative rotation of the nut and threaded shaft, split nuts according to the prior art have been provided. For example, DE1962009, DE102009045289, EP0905390 “Lock nut device”, EP1108902, WO87/07928 “Combi-nut”, W003/025405 “Quick release nut”, GB559,404 “Improvements in tool holding means for drop stamps and other metal working machines”, GB1 , 011 ,474 “Swivel chair support construction”, GB1 ,455,549 “A split nut”, GB1 ,545,707 “Nut”, GB1 ,564,991 “Improvements in/or relating to split nuts”, GB385.631 “An improved nut for bolts, unions or the like”, GB2,239,070 “Dismantleable nuts”, GB2,305,482 “Split nut assembly”, GB2,349,678 “Hinged split nut”, US2010/0158635 ’’Split nut assembly”, US2010/0166525 “Quick attaching and detaching nut”, US2010/0158635 “Split nut assembly”, US2019/0136901 “Quick connect nut”, US730.599 “Nut lock”, US1 ,062,000 “Nut construction”, US1 ,081 ,239 “Nut lock”, US1 ,241 ,432 “Split nut”, US1 ,352,256 “Coupling for metal pipes”, US1 ,360,297 “Quick detachable nut”, US1 ,406,804 “Quick releasable nut and bolt”, US1 ,607,873 “Nut for valve stems”, US2,664,023 “Snap-on split nut”, US3,952,626 “Quick-release fasteners”, US4,274,323 “Shaft-mounted assembly”, US4,378,187 “Quick-acting nut assembly”, US4,462,731 “Split nut assembly”, US5,199,675 “Nut and device using the nut for clamping and supporting elongate objects”, US8,142,127 “Torque nut assembly”, US8,794,892 “Torque nut assembly” describe various embodiments of split nuts.

Furthermore, where the split nut is to be secured to another object axially adjacent to the split nut, it is known for split nuts to define axially extending bores. For example, DE901849, GB855.037 “Improvements in screw-threaded fixings”, US2,377,581 “Divided nut construction” describes diametrically split nuts with axially extending bores for receiving pins, screws or bolts therethrough. However, it is known for pins, screws or bolts that connect the split nut to axially adjacent objects similarly to become subject to forces that cause the pins, screws or bolts to become jammed within the axially extending bores defined by the split nuts. A drawback of known split nuts is that they do not facilitate dissipation of forces between the pins, screws or bolts on the one hand and the split nut on the other hand. It is an object of the present invention to address this drawback and to provide a split nut with axially extending bores through which the split extends.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the invention, there is provided a split nut assembly that includes: a body that defines: a primary threaded bore that extends along a longitudinal axis of the body; and a first pair of secondary bores that: extend through the body parallel to the longitudinal axis of the body; are spaced radially outwards from the primary threaded bore; and are aligned diametrically in respect of the primary threaded bore, characterised in that the body is split into two parts along a plane that extends: along the longitudinal axis of the body; diametrically in respect of the primary threaded bore; and diametrically in respect of each of the first pair of secondary bores.

Typically, the split nut assembly further includes a retaining ring that extends about the radial outer surface of the body. Generally, the body is divided into three axially extending portions, wherein: a first axially extending portion of the body extends from a first axial end of the body, which first axially extending portion defines a cylindrical radially outer surface; a second axially extending portion of the body extends from a second axial end of the body, which second axially extending portion defines a cylindrical radially outer surface; and a third axially extending portion of the body that extends between the first and second axially extending portions, which third axially extending portion defines a cylindrical radially outer surface, wherein: the radius of the cylindrical radially outer surface of the third axially extending portion is greater than the radius of the first axially extending portion; and the radius of the cylindrical radially outer surface of the second axially extending portion is greater than the radius of the third axially extending portion.

Preferably, the third axially extending portion defines two notches that: are aligned with the body split line; and reduce the radius of the radially outer surface of the second axially extending portion to the radius of the radially outer surface of the third axially extending portion.

Typically, the retaining ring is located about the radially outer surface of the third axially extending portion of the body.

Generally, the split nut assembly further includes an intermediate ring that: is located about the radially outer surface of the first axially extending portion of the body; extends beyond the first axial end of the body, and defines a first pair of tertiary bores that are axially aligned with the first pair of secondary bores defined by the body.

Preferably, a first pair of pins extend from the second axial end of the body through the first pair of secondary bores defined by the body and are received within the first pair of tertiary bores defined by the intermediate ring, thereby to inhibit relative rotation of the body and the intermediate ring.

Typically: the body and intermediate ring are located about a main shaft of a crusher; and a mantle bears against the intermediate ring.

Generally: the body defines a second pair of secondary bores that: extend through the body parallel to the longitudinal axis of the body; are spaced radially outwards from the primary threaded bore; are spaced from the first pair of secondary bores defined by the body; and are threaded.

Preferably, the threaded formations defined by the primary threaded bore defined by the body are chamfered in the vicinity of the body split line.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of an example only, with reference to the accompanying drawing in which:

Figure 1 is an upper exploded perspective of a split nut assembly according to a preferred embodiment of the invention; Figure 2 is a lower exploded perspective view of the split nut assembly in Figure 1 ;

Figure 3 is a cross-sectional side view of the split nut assembly in Figure 1 , incorporated in a crusher.

DESCRIPTION OF THE INVENTION

With reference to Figures 1 to 3 a split nut assembly 10 according to a preferred embodiment of the invention includes: a body 12, a retaining ring 14, an intermediate ring 16 and pins I bolts 18.

The body 12 is in the form of a ring that defines: a primary threaded bore 20 that extends along a longitudinal axis A-A of the body; a first pair of secondary bores 22 that: extend through the body 12 parallel to the longitudinal axis A-A of the body; are spaced radially outwards from the primary threaded bore 20; and are aligned diametrically in respect of the primary threaded 20 bore.

Typically, neither of the first pair of secondary bores 22 is threaded.

A split line 32 divides the body 12 into two parts 12a and 12b along a plane that extends: along the longitudinal axis A-A of the body 12; diametrically in respect of the primary threaded bore 20; and diametrically in respect of each of the first pair of secondary bores 22.

Each of the primary and secondary bores 20 and 22 are open at both ends defining a through-bore that extends through the body 12. It will be appreciated that, should the two parts 12a and 12b of the body 12 be separated from each other, the cross-sectional area of the primary and secondary bores 20 and 22 will be increased.

The body 12 is divided into three axially extending portions: a first axially extending portion 24 of the body 20 extends from a first axial end 20’ of the body 20, which first axially extending portion 24 defines a cylindrical radially outer surface (often referred to as a right circular cylindrical outer surface). a second axially extending portion 26 of the body 20 extends from a second axial end 20” of the body 20, which second axially extending portion 26 defines a cylindrical radially outer surface (often referred to as a right circular cylindrical outer surface); and a third axially extending portion 28 of the body 20 that extends between the first and second axially extending portions 24 and 26, which third axially extending portion 28 defines a cylindrical radially outer surface (often referred to as a right circular cylindrical outer surface),

The radially outer surface of the body is stepped in that: the radius of the cylindrical radially outer surface of the third axially extending portion 28 is greater than the radius of the first axially extending portion 24; and the radius of the cylindrical radially outer surface of the second axially extending portion 26 is greater than the radius of the third axially extending portion 28.

Each of the first pair of secondary bores 22 extends through the second and third axially extending portions 28 and 26.

The third axially extending portion 26 also defines two notches 30 that: are aligned with the body split line 32; and reduce the radius of the radially outer surface of the second axially extending portion 26 to the radius of the radially outer surface of the third axially extending portion 28.

The body 12 further defines a second pair of secondary bores 34 that: extend from the second axial end of the body, through the body 12 parallel to the longitudinal axis A-A of the body 12; are spaced radially outwards from the primary threaded bore 20; are spaced from the first pair of secondary bores 22 defined by the body 12 (or, put another way, are angularly offset relative to the secondary bores 22 about the longitudinal axis of the body 12); and are threaded.

Each of the second pair of secondary bores 34 may be through-bores (i.e. being open at both axial ends) or blind bores (i.e being closed at one axial end). Figures 1 and 2 show the second pair of secondary bores as blind bores.

The retaining ring 14 is a metal ring defining right circular cylindrical inner and outer radial surfaces. The axial length of the retaining ring 14 is equal to or less than the axial length of the third axially extending portion 28 of the body 12. Furthermore, the inner diameter of the retaining ring 14 is: greater than the outer diameter of the third axially extending portion 28 of the body 12 when the retaining ring 14 is heated above 150 degrees centigrade; and equal to the outer diameter of the third axially extending portion 28 of the body 12 when the retaining ring 14 is at a temperature of about 30 degrees centigrade. In use, the retaining ring 14 is heated to slip I locate it about the radially outer surface of the third axially extending portion 28 of the body 12. Upon cooling of the retaining ring 14, the retaining ring 14 applies a hoop force to the third axially extending portion 28 of the body 12, thereby restraining the parts 12a and 12b of the body 12 from moving away from each other.

The intermediate ring 16: is located about the radially outer surface of the first axially extending portion 24 of the body 12; extends beyond the first axial end 12’ of the body 12, and defines a first pair of tertiary bores 36 that are axially aligned with the first pair of secondary bores 22 defined by the body 12.

The intermediate ring 16 defines a threaded formation on its radially inner surface, and the first pair of tertiary bores 36 are typically not threaded.

A pair of pins 18 (typically without any threaded formation) extend from the second axial end 12” of the body 12, through the first pair of secondary bores 22 defined by the body 12 and are received within the first pair of tertiary bores 36 defined by the intermediate ring 16, thereby to inhibit relative rotation of the body 12 and the intermediate ring 16 about the axis A-A of the body 12.

Figure 3 shows the split nut assembly 10 incorporated in a crusher. In this application: the body 12 and intermediate ring 16 are located about a main shaft 38 of the crusher; and a mantle 40 bears against the intermediate ring 16.

During operation of the crusher, significant forces are transferred: from the mantle 40 to the intermediate ring 16; and from the intermediate ring 16 to the body 12. These forces can cause: the pins 18 to become jammed (typically due to shear forces generated by relative rotation of the body 12 and the intermediate ring 16): in the first pair of secondary bores 22 defined by the body 12; and/or in the first pair of tertiary bores 36 defined by the intermediate ring 16, thereby: inhibiting axial extraction of the pins 18 from the tertiary bores defined by the intermediate ring 16 and from the secondary bores 22 defined by the body, and causing the body 12 to remain locked against rotation relative to the intermediate ring 16; and causing the body 12 to become jammed against the main shaft 38 of the crusher, thereby inhibiting rotation of the body 12 relative to the main shaft 38 of the crusher.

To facilitate dissipation of these forces, a grinder I cutter I blow torch may be used to cut the retaining ring 14 in the vicinity of the notches 30 defined by the second axially extending portion 26 of the body 12, thereby to separate the retaining ring 14 into two parts that may be removed from about the body 12. The two parts 12a and 12b of the body 12 may then be prised apart from each other to increase the cross-sectional area of the primary and secondary bores 20 and 22. Thereafter: the pins 18 may be axially extracted out of the first pair of tertiary bores 36 defined by the intermediate ring 16 to permit relative rotation between the body 12 and the intermediate ring 16; and the body 12 may be rotated relative to the main shaft 38 of the crusher to remove the body 12 from the main shaft 38 of the crusher.

Following removal of the body 12 from the main shaft 38 of the crusher, the mantle 40 may be removed from the main shaft 38 of the crusher and repaired I replaced.

T o facilitate: prising of the two parts 12a and 12b of the body 12 away from each other; and rotation of the body 12 relative to the main shaft 38 of the crusher, a tool (not shown) may be secured to the body 12 via bolts 18 that are threadably inserted into the second pair of secondary bores 34.

Furthermore, to reduce damage to threaded formations on the main shaft 38 of the crusher during rotation of the body 12 relative to the main shaft 38 of the crusher, the threaded formations defined by the primary threaded bore 20 defined by the body 12 are chamfered in the vicinity of the body split line 32.

It will be appreciated that by passing the split line 32 through both the primary and secondary bores 20 and 22, the split nut assembly 10 addresses both: jamming of pins 18 within the first pair of secondary bores 22; and jamming of the body 12 on the main shaft 38 of the crusher.