WO1992014941A1

WO1992014941A1 - Arrangement in pivots

Info

Publication number: WO1992014941A1
Application number: PCT/NO1992/000027
Authority: WO
Inventors: Arne Aarre; Knut Sigvald Oaland
Original assignee: Arne Aarre; Knut Sigvald Oaland
Priority date: 1991-02-14
Filing date: 1992-02-12
Publication date: 1992-09-03
Also published as: AU1209392A; NO910588L; NO910588D0

Abstract

A pivot (3) is adapted to secure relative pivotability between two adjacent members (1, 2), which may be subjected to very large external forces and loads. Adjacent portions of said two members (1, 2) are formed with aligned bores (1', 2') for the accommodation of the pivot (3), which comprises a bolt (4) having conically tapering end portions. Each of the conical end portions of the bolt is surrounded by an internal conical sleeve (5), a so-called cone, which is assigned a screwable means (6, 7), such as a nut, displaceable through screwing along the axial direction of the bolt (4). In order to effect the tightening of the cones (5) upon assemblage and the extraction thereof upon disassemblage by means of one and the same means, namely the screwable means (6, 7), the latter is turnably, axially non-displaceably connected to the associated cone (5).

Description

ARRANGEMENT IN PIVOTS

This invention relates to an arrangement in a pivot adapted to secure a relative pivotability between two adjacent constructional parts, the mutually adjacent portions thereof being formed with aligned bores for the accommodation of a bolt incorporated into the pivot.

Pivots of the kind with which the invention is occupied, have a wide and very general field of applications and may, in principle, be used in every case requiring a relative swing joint between two adjacent constructional members to be established. As non-restnctmg examples of such swing joints may be mentioned pivots for boom constructions of agriuitural implements, construction site vehicles/

machines, e.g. excavators and lifting cranes. Likewise, equipments for the offshore oil industry also require such swing joints and pivots, e.g. for pivotal suspension of a block with a hook. Often, such pivots are subjected to enormous external forces with corresponding loads and strains acting on adjacent constructural part portions, resulting in a substantial wearing between the bolt and the surrounding bore-defining inner walls. Also, said loads and strains may result in that the bore walls become beaten-out, so that the bore(s) attain(s) a non-circular, approximately oval cross-section, so that the shape-fixed engagement/support of the bolt within the bore(s) is deteriorated.

Often, the bolt of the pivot has a double-conical shape, i.e. that the bolt from a preferably cylindrical sentral portion tapers evenly toward each outer end thereof.

In order to accommodate slackness/clearance between such a double-conical bolt and the surrounding bore wall, it is previously known to arrange a split cone at each end of the bolt, said split cones being retightened when necessary.

Such a split cone has the form of a split sleeve having a tapering inner wall, the conisity thereof substantially corresponding to the taper of the end portions of the bolt. A disadvantage when using such cones is that they easily get stuck within the bore through corrosion or wedging.

Even if such slackness-accommodating end cones should not get stuck through rust or wedged up, they will not be easily removable, e.g. when exchanging the bolt, because they cannot be pressed axially out, each split cone acting as an soutment preventing the extraction of the other split cone.

There would be a need for removing such cones both when disassembling equipment for inspection/maintenance/repair and whenever the bolt or other parts of the pivot have been worn out and must be exchanged.

Today, one tries to worm the cones out by imparting blows thereto alternately from opposite sides. This is a difficult and time-consuming work, which often fails because the cones nave become stuck through wedging/corrosion. Therefore, sucr. failure may result in that one burns the cones loose by means of a cutting burner. This necessitates the welding-in of a new piece of material around the attachment area as well as line drilling of new bores, which is very costly. I n order to be capable of pressing in such end cones onto a double-conical bolt's two end portions, the bolt may, according to prior art technique, be provided with a

through-going bore accommodating a through-going shaft, the and portions thereof being threaded. Onto the snaft a discehaped ring has been threaded from each end, said rings, by means of individual, axially outwardly positioned nuts, press the cones toward each other from each outer end of the oolt. An obvious disadvantage in such a solution is that the t hrough-going shaft considerably weakens the bolt and, thus, requires a lateral overdimensioning in order to maintain the necessary strength. In accordance with the present invention, the above- mentioned deficiencies and disadvantages are to be

eliminated or substantially reduced, simultaneously as simplifications as well as improvements m other respects are sought to be achieved.

According to the invention, said objects are realized through designing the pivot as set forth in the following claims. In accordacne with the invention, the bolt of the pivot, which is lacking a t hrough-going, strengtn-reducing bore, has at each end a threaded coaxial pin for a nut engaging the p in threads, said nut being in turnable, axially non-displaceable connection to an adjacent slackness-accommodating cone.

Thereoy, one nas arrived at a solution wherein excactly the same means (the nuts) causing the pressing-in of the cones during assemblage, enable the extraction of the cones when disassembling the connection.

When a nut wnich is turnably, axially non-displaceably connected to a cone, is screwed inwards on one or trie threaded end pms of the bolt, the cone is displaced inwardly, engaging the conical portion of the bolt body, in order to establish the active, pressed-in position of the rone, as known per se.

When the connection is to be disassembled, the nut will also during its unscrewing movement along the bolt's threaded pin act as a carrier for the cone and pull it along and bring the engagement between the cone and the conical portion of the bolt to an end.

The turnable, axially non-displaceable connection of the nut to the cone may be effected in many different ways.

An example of an embodiment of the invention is explained further in the following, reference being made to the accompanying drawings, wherein:

Figure 1 is a partial view in axial section and shows a swingable joint between two constructional parts, including a pivot according to an embodiment of the invention;

Figure 2 snows a detailed view of figure 1 on a larger scale:

Figure 3 shows an exploded side elevational view of parts of figure 2.

In the drawings, reference numeral 1 denotes an upper portion of e.g. a hook (e.g. a socalled drilling hook) wnerein underlying equipment may be suspended, e.g. during oil drilling.

The first construction member 1 is pivotaliy connected to a second, overlying construction member 2 by means of a pivot generally denoted by the reference numeral 3. Second

construction member 2 may be incorporated into an

arrangement of tacκles etc. or constitute a boom arm

included in a boom for an excavator, a lifting crane or the like.

Thereby, adjacent portions of the two construction members 1,2 are formed with aligned lateral bores 1' and 2',

respectively, for the accommodation of the through-going pivot 3, the hook-shaped construction member 1 having a bifurcated end portion wherein the adjacent end portion of the overlying construction member 2 is engaged, a suitable clearance being maintained to the adjacent opposing faces of the bifurcated parts.

The pivot 3 comprises as primary element a double-conical bolt 4 which, from a substantially cylindrical sentral portion 4', in the area of the bore 2' of the upper

construction member 2, tapers smoothly toward each outer end.

The bolt 4 is assigned two internal conical slackness-accommodating sleeves 5, socalled cones, having the same tonisity as the bolt 4, and which may be brought to surround the conical end portions of the bolt 4 partly or wholly.

These internal conical sleeves 5 have cylindrical external mantle face and are accommodated within the bores 1' of the lower construction member 1.

In the following, for the sake of simplicity, these internal conical, slackness-accommodating sleeves have been

designated "cones".

At each outer end, the double-conical bolt 4 is formed with a coaxially protruding threaded pin 4", which may be formed integrally with the bolt body 4, or they may be constituted by separate threaded pins screwed tightly into corresponding blind bores at each end of the bolt 4.

Each of these threaded pins 4" carries a displaceable nut 6.

In accordance with the present invention, each of these nuts D is turnbly, axially non-displaceably connected to its assigned cone 5, so that the respective nut 6 may be rotated in relation to the cone, but not displaced axially in relation to the latter.

Thus, the respective nut forms a carrier means for axially directed displacement movement of the assigned cone 5, more specifically a carrier capable of carrying along the cone 5 in any one of two mutually opposite directions extending along the axis of the bolt 4.

This relatively turnable/rotary, axially non-displaceable connection between nut 6 and cone 5 enables assembling tightening as well as disassembling extraction of each cone 5 by means of one and the same means, the nut 6, during the rotary movements of the latter along the assigned threaded pin 4" thereof.

Thereby, a particularly advantageous disassemblage of the cones 5 is achieved, the arrangement according to the invention securing extraction of the cones even if they should have become stuck to the bolt through wedging or corrosion. In accordance with the invention, the positioning and tightening of the cones 5 are obtained without hollowing out or weakening the bolt body 4 through an axially through-going bore according to prior art technique.

According to the embodiment shown, said relatively rotary, axially non-displaceable connection between respective nut and cone has been established by means of a collar 7 formed integrally with the nut 6, said collar 7 along the

circumference thereof engaging turnably, axially non-dispiaceably into a complementarily shaped, internal

circumferential groove 8 within the cone 5.

The engagement between the collar 7 of the nut 6 and the internal circumferential groove 8 of the cone appears best from figure 2 in association with figure 3.

The circumferential portion of the collar 7 is of

trapezoidal cross section, and being defined by the

peripheric circle-annular face 9, a radially extending stop face 10 coinciding with the gable face of the collar 7, as well as an inclined stop face 11 forming an acute angle with trie first-mentioned stop face 10.

As mentioned, the internal groove 8 of the cone 5 is of a corresponding cross-sectional shape complementary to that of the collar 7, and comprises a peripheric inner face 12 which, at one side thereof, passes into a radial impact or counter face 13 and, at the other side thereof, passes into an inclined impact or counter face 14.

In order to establish the engagement between the collar 7 of the nut 6 and the internal circumferential groove 8 of the cone 5 (presupposing rigid parts 6,7 and 5 lacking inherent flexibility), the cone 5 - according to the embodiment shown

- has been divided into two cone halfs, the bisecting plane

- in this embodiment - extending in the axial plane of the cone 5.

However, said engagement between cone 5 and nut 6 may also be established without dividing the cone 5 into two or more parts, namely by imparting a certain radial flexibility to the cone and/or to the nut, e.g. through the arrangement of a plurality of axially extending slots (in cone and/or nut), said slots being through-going radially but, of course, not extending over the entire axial length of the cone and/or of the nut. Split cones of a kind suitable for the purpose of the present invention are previously known and available m a number of different embodiments.

Thereby, the clearance between the peripheric engagement portion 9,10,11 of the nut collar 7 and the internal

circumferential groove 8 of the cone is choosen so that the members 6,7 and 5 may be rotated in relation to each other without any problems. On the other hand, the stop face 10 of the nut colar 7 cooperates with the counter face 13 defining the internal circumferential groove 8 of the cone 5 in one axial direction, the stop face 11 of the collar cooperating with the counter face 14 defining the extent of the groove 8 in the opposite direction, so that a connection between cone 5 and nut 6 via collar 7 is established, said connection being relatively non-displaceable in opposite axial directions.

It should be clear without saying that a screwing movement of the nut 6 along the threaded pin 4" takes place during the nut's 6 rotation in relation to the assigned cone 5 during a simultaneous displacement of the connected nut cone-assembly in one or the opposite direction along the axis of the bolt 4, dependent on the rotational direction of the nut 6.

When using a divided cone according to figure 3, the cone halfs are placed in a slight V-shape when they are displaced inwardly onto the bolt 4, until the nut collar 7 has been positioned within the cone halfs (occupying the space defined by the groove 8).

Details relating to the arrangement of the invention may be varied and modified within the scope defined by the following claims. Thus, the threaded pins 4" made integrally with the bolt body 4 of the pivot, may e.g. be constituted by separate threaded pins adapted to oe screwed fixedly into corresponding tnreaded axial blind bores of the bolt body 4. Insertion/extraction of the cones 5 will, however, alwaystake place by means of a rotary nut wnich, upon screwing/unscrewing movements thereof, displaces itself to and fro along the longitudinal axis of the pivot bolt 4.

Claims

C l a i m s

1. An arrangement in a pivot (3) adapted to secure relative pivotability between to adjacent members (1,2), the mutually adjacent portions of which are formed with bores (1',2') for the accommodation of the pivot (3), said pivot comprising a belt (4) having conically tapering end portions each

surrounded by a corresponding, internal conical sleeve (5), a socalled cone, which is assigned a screwable means (6), such as a nut, adapted for displacement along the axial direction of said bolt (4), c h a r a c t e r i z e d i n that said screwable means (6) is turnably, axially

non-displaceably connected to the associated cone (5).

2. An arrangement as set forth in claim 1,

c h a r a c t e r i z e d i n that the bolt (4) of the pivot (3), at each outer end thereof, is provided with a threaded coaxial pin (4") for said screwable means (6).

3. An arrangement as set forth in claim 2,

c h a r a c t e r i z e d i n that the screwable means (6) carries a rigidly attached collar (7), or the like, designed to engage turnably, axially non-displaceably into an internal circumferential groove (8) within the associated cone (5).

4. An arrangement as set forth in claim 3,

c h a r a c t e r i z e d i n that the circumferential portion of said collar (7) or the like is of trapezoidal cross section having two spaced, oppositely facing stop faces (10,11) which, within the complementarily formed internal circumferential groove (8) of the cone (5), each cooperate with an opposing counter face (13,14) defining said groove (8).

5. An arrangement as set forth in one or more of the claims 1 - 4, c h a r a c t e r i z e d i n that each cone (5) is divided into at least two longitudinal parts, the

partition plane, preferably, coinciding with the axial plane of the respective cone (5).